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1976 Service Manual - 73

1. SPECIFICATIONS 25 TORQUE 55 75 Ft 75 100 Ft 90 120 Ft 110 140 Ft TRUCK SUPP SPECS Lbs Lbs Lbs Lbs SPECIFICATIONS 26 BODY AND CHASSIS ELECTRICAL SECTION 12 FUSES CIRCUIT BREAKERS The wiring circuits are protected from short circuits by a combina tion of fuses circuit breakers and fusible thermal links in the wiring itself This greatly reduces the hazard of electrically caused fires in the vehicles The headlamp circuits are protected by a circuit breaker in the light Switch An electrical overload on the breaker will cause the lamps to go on and off or in some cases to remain off In addition to a fuse the windshield wiper motor is also protected by a circuit breaker If the motor overheats due to overloading caused by heavy snow etc the wipers will remain stopped until the motor cools Fuses located in the Junction Block beneath the dash on the drivers side are C K TRUCK Heater Front A C Generator Warning Lamp 20 Amp Idle Stop Solenoid Aux Battery Radio Time Delay Re lay Emission Control Solenoid Transmission Dens tidy 15 Cigarette Lighter Clock Dome Lamp Cargo Lamp 20 Amp Fuel Gauge Brake Warning Lamp Temperature Warn ing Lamp Oil Pressure Warning Lamp 4 Amp Courtesy Lamp Roof Marker Lamp License Plate Lamp Parking Lamp Side Marker Lam
2. 6 41 GENERAL DESCRIPTION M4MC M4ME model Quadrajet carburetors fig 36 and 36A are two stage carburetors of downdraft design The triple venturi system with 1 7 32 venturi is used on the primary side of the Quadrajet carburetor with small 1 3 8 throttle valve bores The triple venturi stack up plus small primary throttle valve bores results in good fuel control during idle and part throttle operation The secondary side has two large bores 2 1 4 Using the air valve principle in the secondary side fuel is metered in direct proportion to the air passing through the secondary bores The carburetor part number is stamped on a vertical section of the float bowl near the secondary throttle lever Refer to the part number on the bowl when servicing the carburetor When replacing the float bowl assembly follow the manufacturer s instructions contained in the service package so that the part number can be transferred to the new float bowl A throttle return control system with bracket is used on some California light duty truck with heavy duty emissions and V8 engine The vacuum unit and bracket assembly is mounted on the float bowl When manifold vacuum is high such as on deceleration the vacuum diaphragm plunger moves outward contacting the throttle lever to open the primary throttle valves slightly to lean out the rich air fuel mixture in the intake manifold The throttle return control syst
3. 1MV MONOJET CARBURETOR INDEX General Description ertt terrent tete 6M 1 Fast Idle Adjustment a Theory of Operation na nere 6M 2 Fast Idle Cam Adjustment 22 0222222 Float Sy SCCM as uude cete eine 6M 2 Choke Coil Rod Adjustment 0 2 42 2 Idle System nh evt at 6M 3 Primary Vacuum Break Adjustment Main Metering System sese 6M 4 Auxiliary Vacuum Break Adjustment Power Enrichment System 6M 5 Choke Unloader Adjustment ess Accelerating Pump System sess 6M 5 Service Operations esses Choke ua a i a tate Sau awa 6M 6 Carburetor Replacement aa Maintenance and Adjustments sess 6M 7 Fuel Filter Replacement a aa Idle Speed eene tette 6M 7 Idle Stop Solenoid 1 Low Idle and Curb Idle Choke Coil Replacement seen Speed Adjustment sse 6M 7 Air Horn Tightening Sequence Idle Mixture A 6M 8 Diagnosis oe eei IE Idle Mixture Adjustment seen 6M 8 GENERAL DESCRIPTION The Monojet carburetor is a single bore downdraft carburetor fig 1 using a triple venturi in conjunction with a plain tube nozzle
4. eee 7M 8 OVERHAUL OPERATIONS TRANSMISSION DISASSEMBLY 3 Remove long spring that retains the detent plug in the case fig 4R Remove the detent plug with a small 1 Remove lower extension housing bolt and drain magnet transmission fig 3R 4 i i 2 Remove top cover and gasket from case Remove extensi n hOUSID and saiket Fig 1R 3 Speed Tremec TRUCK SUPP OVERHAUL S M a M Vu M M nmwneceesuu 0 0 c c X s 7M 2 MANUAL TRANSMISSION 19 Press down on speedometer gear retainer and remove speedometer drive gear and retainer from output shaft Remove fill plug from right side of case fig 3R Working through the plug opening drive out countergear roll pin with a 3 16 inch pin punch that has been chamfered slightly NOTE Do not attempt to retrieve pin at this time Pin can easily be retrieved after output shaft assembly is removed Insert dummy shaft tool J 25232 into bore at front of case tap lightly on tool to push countershaft out rear of case fig 5R NOTE With countershaft removed allow countergear to lie at bottom of case Punch alignment mark in front bearing retainer and transmission case to ensure correct assembly and remove front bearing retainer and gasket fig 6R Remove large locating snap ring from front bearing and smaller snap ring from clutch gear shaft Rem
5. 18 ft Ibs Bracket to Floor 55 ft lbs Gravel Deflector 85 in Ibs Rear Step Bumper to Bracket or Frame 40 ft lbs ACCESSORIES SECTION 15 CRUISE MASTER Solenoid Resistance GE Gree rer 5 ohms 1 4 ohm Solenoid Wire Resistance 40 ohms Maximum allowable Vacuum Leakage rate for Servo unit 5 inches of Vacuum Per Minute Not Greater than 1 inch of Vacuum per 10 seconds Operational Test A eve dra lor are SCR e POSU M adr GAS TB 55 MPH TRUCK SUPP SPECS CHEVROLET
6. 0 1 TOWNE rope pre HUN pe 0 4 Truck Model Identification All 10 30 series models are identified by this model system Basically the designation consists of 7 characters 2 letters followed by five numbers The first letter indicates a Chevrolet model and the second identifies the chassis type The first number designates the GVW range the second and third identify the cab to axle dimension or model type and the last two identify the cab or body style VEHICLE IDENTIFICATION NUMBER AND RATING PLATE A combination vehicle identification number and rating plate used on all models fig 1 is located on the left door pillar of CK models On Forward Control models except P30 Motor Home Chassis it is attached to the dash and toe panel The vehicle identification number stamped on the plate decodes into the information shown in Figure 2 Plate Information ENGINE NUMBER The engine number indicates manufacturing plant month and day of manufacture and transmission type A typical engine number would be FI210TFA which would breakdown thus F Manufacturing Plant F Flint T Tonawanda 12 Month of Manufacture December 10 Day of Manufacture tenth T Truck FA Transmission and engine type UNIT AND SERIAL NUMBER LOCATIONS For the convenience of service technicians and engineers when writing up certain business papers such as Warranty Reports Product Information Reports or reporting produc
7. NORMAL RESULT ENGINE ACCELERATES VACUUM REINSTALL LARGE HOSE AT REGULATOR CHECK FOR VACUUM AT ITCH DEPRESSED HALFWAY REMOVE HOSE AT SERVO END OF HOSE ENGAGE VACUUM NO VACUUM CHECK HOSES AND FITTINGS BACK TO REGULATOR REPLACE SERVO UNIT CHECK BRAKE RELEASE VALVE AND 9 Diagnosis Chart No 2 TRUCK SUPP SERVICE SECTION INDEX 1 97 6 AIR CONDITIONING COMPRESSOR 10 30 SERIES TRUCK FRONT AXLE CHASSIS SERVICE and REAR AXLE DIFFERENTIAL CARRIER OVERHAUL MANUAL The overhaul section of this manual includes new or re rn vised procedures involved in disassembly and assembly of major components STARTING MOTOR SOLENOID AND DELCOTRON CLUTCH AND LE AUTOMATIC TRANSMISSION MANUAL STEERING GEAR POWER STEERING PUMP AND GEAR SPECIFICATIONS AT REAR OF MANUAL Printed In U S A SECTION 1 AIR CONDITIONING CONTENTS OF THIS SECTION Axial Six Cylinder Compressor Radial Four Cylinder Compressor Special Fools nee rente AXIAL SIX CYLINDER COMPRESSOR INDEX Minor Repair Procedures sse 1 1 Shaft Seal Me e ueteres 1 8 Clutch Plate and Hub Assembly 1 3 Pressure Relef ee cen e 1 11 Pulley and Bearing Assembly 1 4 Internal Mech nism 1 11 Clutch Coil and Housing Assembly 1 7 Leak Tes
8. P UP en aedis 6M 20 GENERAL Air Horn Before performing any service on the carburetor it is essential that the carburetor be placed on a holding fixture such as Tool J 8328 Without the use of the holding fixture it is possible to bend or nick throttle valves Fig IMQ and 1MQ A DISASSEMBLY Throttle Lever Actuator Remove the throttle lever actuator vacuum unit and bracket assembly used on some truck applications CAUTION The throttle lever actuator should not be immersed any type of carburetor cleaner and should always be removed before complete carburetor overhaul Fig 1M0 M4MC Quadrajet Carburetor Remove upper choke lever from the end of choke shaft by removing retaining screw Fig 2MQ Then rotate upper choke lever to remove choke rod from slot in lever 2 Remove choke rod from lower lever inside the float bowl casting by holding lower lever outward with small screwdriver and twisting rod counterclockwise 3 Remove secondary metering rods by removing the small screw in the top of the metering rod hanger Lift upward on metering rod hanger until the secondary metering rods are completely out of the air horn Metering rods may be disassembled from the hanger by rotating ends out of the holes in the end of the hanger Fig 3MQ 4 Using special tool J 25322 drive small roll pin pump lever pivot pin inward just enough until pump lever can be removed from air horn Then remove pump lever from p
9. 1 gita NI MJ N N 11415 29 16 MODELS CD ICM CP CR amp CZ 1 lt J Manual Valve 1 2 Detent Valve Retaining Pin 1 2 Regulator Valve Bore Plug Spring Detent Valve 1 2 Regulator Valve Detent Regulator 1 2 Modulator Valve Bushing Spacer Retaining Pin Detent Regulator Retaining Pin Valve Spring Bore Plug 1 2 Shift Valve AUTOMATIC TRANSMISSION 7A 7 20 21 22 23 Num 25 26 27 28 1 2 Accumulator 2 3 Modulator Valve Bushing 1 2 Primary Retaining Pin Accumulator Spring 3 2 Valve 2 3 Shift Valve Spacer 3 2 Intermediate Spring 2 3 Modulator Valve 2 3 Shift Vaive Spring 3 2 Valve Spring Bore Plug Retaining Pin 1 2 Accumulator Valve Sec Spring Fig 7B Control Valve Assembly Exploded View 11 Install 2 3 modulator valve into 2 3 accumulator bushing and install both parts into valve body bore 12 Install 2 3 valve spring and retaining pin 13 In next bore up install 1 2 valve train as follows a All models except CJ and CP install the 1 2 shift valve stem end out Install the 1 2 regulator valve larger stem end first 1 2 regulator spring and 1 2 detent valve open hole first into the 1 2 modulator bushing aligning the spring in the bore of the detent valve Install these parts into the valve body bore b Models CJ and CP install the 1 2 shift valve stem end out Install 1 2 modulator valve 1 2 modul
10. Assembly of Transfer Case DISASSEMBLY OF TRANSFER CASE Refer to figures 1F and 2F for cross sectional 1 Position transfer case on work bench or suitable work table Fig 3F and 4F NOTE If lubricant was not drained from unit prior to removal from vehicle remove front output rear cover and P T O cover lower bolts and drain lubricant into waste container 2 Using Tool J 8614 1 loosen rear output shaft flange retaining nut 3 Using Tool J 8614 1 remove front output shaft flange retaining nut washer and flange NOTE Tap dust shield rearward on shaft away from bolts to obtain clearance to remove bolts from flange and allow installation of Tool J 8614 1 4 Remove bolts retaining front output shaft front bearing retainer Remove bearing retainer and gasket from transfer case Discard gasket 5 Using a hoist or other suitable lifting tool position assembly on blocks 6 Remove bolts retaining rear section of rear output housing assembly from front section of rear output housing and disengage Remove shims speedometer gear from output shaft 14 7 Rem ve bolts retaining front section of rear output housing assembly from transfer case Remove housing from transfer case 8 Remove O ring seal from front section of rear output housing and discard 9 Disengage rear output shaft from differential carrier assembly Slide carrier unit from shaft NOTE A 1 1 2 to 2 water hose band
11. H Am wYw Jw r arpa wm 6Y 8 ENGINE ELECTRICAL 2 Read voltage after 15 seconds with load connected and then disconnect load MINIMUM VOLTAGE 3 If minimum voltage is 9 6 volts or more battery is good 4 If minimum voltage is less than 9 6 volts replace battery This voltage is to be used for battery ambient temperatures of 70 F and above For temperatures below 70 F use the following 10 SI SERIES GENERATOR The 1976 10 SI generator is mostly carryover from 1974 The only difference being that a 40 ohm resistor has been added to the warning indicator circuit figs 1 and 2c The purpose of this resistor is to provide a definite warning indicator light in the case of an open field circuit in the generator Refer to Section 6Y of the 1974 Truck Service Manual for all service procedures BRUSH HOLDER 40 OHM RESISTOR 9 0 INDICATOR SWITCH DIODE TRIO J REGULATOR INSULATING WASHER D FIELD ROTOR 0000000000 B i 992 GROUNDED HEAT SINK Fig 2C Resistor Location STATOR RECTIFIER BRIDGE Fig 1C Integral Charging System Circuitry TRUCK SUPP SERVICE ENGINE ELECTRICAL 6Y 9 STARTER SYSTEM The 1976 starter is mostly carryover from 1974 The only difference being that the R terminal of the starter so
12. Imm RM RR RR TIE EE ET 5 2 BRAKES MERCHANDIZING BRAKE MODEL TON RATING WHEELBASE GVW RATING OPTION SYSTEM C10516 1 2 106 5 6050 6200 Base JB5 C10703 117 5 4900 Base JB1 5300 5600 450 JB3 5300 6200 455 JB5 C10903 131 5 4900 Base JB1 5300 5600 450 JB3 5300 6200 J55 JB5 C10906 129 5 6050 7000 Base JB5 C20903 3 4 131 5 6400 7100 Base JB6 6400 8200 J55 JB7 C20906 129 5 7100 Base JB6 7100 8200 455 JB7 C20943 164 5 7500 8200 Base JB7 C20963 8200 Base JB7 i mH E o A C30903 1 131 5 6600 8200 Base JB7 6600 10000 455 JB8 C30943 164 5 9000 10000 Base JB8 C30963 9000 10000 Base JB8 C31003 135 5 6600 8200 Base JB7 6600 10000 455 JB8 C31403 159 5 6600 8200 Base JB7 6600 10000 J55 JB8 TRUCK SUPP SERVICE BRAKES 5 3 BRAKE SYSTEM APPLICATION continued MERCHANDIZING BRAKE MODEL TON RATING WHEELBASE GVW RATING OPTION SYSTEM K10516 1 2 106 5 6200 6300 Base JB5 K10703 117 5 6200 6400 Base JB5 K10903 131 5 6200 6400 Base JB5 K10906 129 5 6200 7300 Base JB5 e a a a K20903 3 4 131 5 6800 Base JB6 6800 8400 J55 JB7 K20906 129 5 6800 Base JB6 6800 8400 J55 JB7 G11005 1 2 110 4800 Base JB1 4800 5600 J50 JB3 G11006 5400 5600 Base JB3 G11305 125 4900 Base JB1 4900 5600 J50 JB3 G11306 5600 Base JB3 G21005 3 4 110 6400 Base JB5 G21006 6400 Base JB5 G21305 125 6400 Base JB5
13. STRIKER ADJUSTMENT Fig 6 Rear Door Striker and Wedge Adjustments Removal is accomplished using the following procedure 1 Pull up on quick release latches located at lower front of seat legs right and left hand sides 2 Tilt up front of seat and push seat rearward to clear anchor pins located beneath floor at front and rear of seat legs 3 Lift seat up and remove from van 4 To replace reverse steps 1 to 3 CAUTION Wen replacing seats make sure that seat retainer hooks are fully engaged with anchor pins and latching assembly 18 fully depressed into place TRUCK SUPP SERVICE 18 2 Boor ASM ARO NS dd yor 9097 _genvict SECTION 2 FRAME redesigned This design change has necessitated moving the kick up back approximately three inches Truck frames are essentially carryover with some models undergoing reference alignment and configuration dimension changes The 10 30 series frames and related dimensions are shown in figures 1 through 3 On C107 and 109 models due to shifting the position of the catalytic converter the left hand converter rail has been 16 7 8 16 7 1 2 16 7 8 155 1 uo fiee 17 3 4 69 5 8 16 7 3 4 6958 120 16 778 1678 14 17 3 17 3 10 72 1 4 17 3 4 17 3 4 1 a ens rev no pes ez lt nimm e sti
14. DEFROSTER Check performance by moving controls to DEF and noting amount of air directed against the windshield REARVIEW MIRRORS AND SUN VISORS Check that friction joints are properly adjusted so mirrors and sun visors stay in the selected position HORN Blow the horn occasionally to be sure that it works Check all button locations LAP AND SHOULDER BELTS Check belts buckles latch plates retractors reminder systems and anchors for proper operation or damage Check to make certain that anchor mounting bolts are tight HEAD RESTRAINTS Check that head restraints if present adjust properly in the up detent positions and that no components are missing damaged or loose SEAT ADJUSTERS Check that seat adjusters securely engage by pushing forward and backward whenever a manual seat is adjusted SEAT BACK LATCHES Check to see that seat back latches are holding by pulling forward on the top of each folding seat back LIGHTS AND BUZZERS Check all instrument panel illuminating and warning lights seat belt reminder light and buzzer interior lights license plate lights side marker lights headlamps parking lamps tail lamps brake lights turn signals backup lamps and hazard warning flashers Have headlamp aim checked every 12 months or 15 000 miles or more often if light beams seem to be aimed improperly GLASS Check for broken scratched dirty or damaged glass on
15. Place a new gasket on the bottom of the float bowl with holes in gasket aligned with holes in casting then position the throttle body on gasket and install the three attaching screws Tighten screws evenly and securely Float Bowl 1 2 Install two main metering jets into bottom of float bowl Fig 5C Install power valve and gasket into bottom of float bowl using slotted screwdriver Tighten securely 3 CARBURETOR 6M 9 Drop small aluminum inlet check ball into hole in pump well install pump return spring pressing with finger to center in pump well Drop steel pump discharge ball into pump discharge hole located beneath the venturi cluster Ball is 3 16 diameter do not confuse with aluminum inlet ball Install pump discharge ball spring and retainer Install plastic main well inserts into the main fuel wells located beneath the venturi cluster and make sure they are seated in recesses provided Fig 6C Then install venturi cluster and gasket tighten three screws evenly and securely Make certain center screw is fitted with a gasket to prevent pump discharge leakage Air Horn Fig 4C 1 9 Install the upper choke rod lever and collar assembly on to choke shaft Then install the choke shaft assembly into the air horn from the throttle lever side Then install the choke valve onto the choke shaft with the letters RP or part number facing upward Install the choke valve attaching sc
16. C K G Overhead Systems 5 Ibs 4 oz C K Models 13 5 6 25 Max 2550 Min G Model C60 System 3 Ibs 2950 Max Motor Home Chassis Unit 3 lbs 4 oz G Models 13 5 7 1 Max 2850 Min 3250 Max 555 Viscosity Compressor Oil 6 Cylinder Axial 10 5 Fluid oz Fuses 4 Cylinder Radial 6 0 Fluid oz oo AP M 20 Amp Overhead Systems 13 oz G Models t qe ucc 20 Amp Torque Specifications AUXILIARY HEATER Compressor Suction and Discharge A PM Connector Bolt 22 ft lbs RN gt Rear Head to Shell Stud Nuts 6 Cyl 23 ft lbs Volts Cold Shaft Mounting Nut 6 Cyl 20 ft Ibs Blower Motor 13 5 9 6 Max 2700 Min Shaft Mounting Nut 4 Cyl 8 12 ft lbs High Pressure Relief Valve 6 Cyl 12 ft Ibs Oil Charge Screw 6 Cyl 14 ft Ibs AIR CONDITIONING Air Gap on Clutch 6 Cyl 022 to 057 in Compressor Mounting Bracket Bolts 20 ft Ibs ompressor ee Front Bracket to Compressor Bolts aeg Frigidaire 6 Cyl 2 2 20 ft lbs PY DC PET EE 6 Cylinder Axial Compressor Mounting Bracket Bolts 4 Cylinder Radial 4 Cyl 18 ft lbs si uer users zt T SE E 6 Cylinder Ta m ge oe Eo Ue 5
17. IE 6 5 ENGINE TUNE UP Refer to 1974 Service Manual for the following engine may occur Disregard all references to performing tune up procedures a Cylinder Balance Test on 1976 vehicles that be found in past or present model service e Spark Plug Service publications Tast FUEL SYSTEM SERVICE e lonition Service Refer to Section 6M of this publication for fuel system e Battery Service timing idle speed and carburetor adjustment service e Generator Service procedures e Drive Belts Service EMISSION SYSTEM SERVICE e Fuel Lines and Fuel Filter Service Refer to Section 6T of this publication for servicing emission system related components e Cooling System Service IGNITION SYSTEM SERVICE e Instrument Check Out 22 26 m UE 3 Refer to Section 6 of this publication for servicing High Additional Checks and Adjustments Energy Ignition HEI system CAUTION When performing engine diagnosis VEHICLE MAINTENANCE or tune up on 1976 vehicles equipped with catalytic converters DO NOT use the Cylinder During engine tune up the Complete Vehicle Maintenance Balance Test as described in 1974 Service Schedule or Section O of this manual should be checked Manual as damage to the emission control system and all required checks and services should be performed TRUCK SUPP SERVICE SUPP SERVICE 6 2 ENGINE Ve ENGINE MECHANICAL IN LINE ENGINES COMPONENT REPLACEMENT AND ADJUSTMENT
18. 16 5 x 6 75 16 x 61 2L 16 5 x 8 25 15 x 6JJ 15 x 6 JJ 19 5x 6 75 16 x 6K 19 5 x 5 25 2800 Load Range Replaces Ply Rating 2 175 5 25 4 6 8 TRUCK SUPP SERVICE SECTION 11 CHASSIS SHEET METAL INDEX General Description Ja eet e rete 11 1 Rear Fender CK Series 11 1 Maintenance and Adjustments 11 1 Running Board CK 6 2222 2 11 1 Hood Lock Assembly CK Series 11 1 Hood Rod Support G 11 1 Carburetor Air Inlet Snorkels CK 11 1 GENERAL DESCRIPTION The service procedures for all 1976 truck chassis sheet metal are essentially the same as those outlined in the 1974 Light Duty Truck Service Manual Section 11 except as described below MAINTENANCE AND ADJUSTMENTS To repair or replace either the hood lock assembly or the carburetor outside air inlet snorkels the radiator grille must T S be removed prior to disassembly n X9 HOOD LOCK CATCH Refer to Section 13 Radiator and Grille of the 1976 Light as Duty Truck Service and Overhaul Manual for proper procedures HOOD LOCK ASSEMBLY Service procedure for the 1976 CK Series hood lock is essentially the same as outlined in the 1974 Light Duty Truck Service Manual Section 11 except for the slight
19. 3 Transmission 2 2222222 7 2 Transmission Replacement eese 3 Draining and Refilling Transmission TA 2 ttt eet ee desees 4 Shift Control Saee e hat TA 2 Pressure Cheek a entered TAA Column Shift Linkage Series 7A 2 Spring Tension Comparison Check 4 Detent Downshift Cable 7A 2 VACUUM MODULATOR amp VALVE ac lt e e Fig 16 Vacuum Modulator Assembly VACUUM MODULATOR ASSEMBLY FIG 1G The engine vacuum signal is provided by the vacuum modulator which consists of a diaphragm and one spring The external spring applies a force which acts on the modulator valve This force acts on the modulator valve so that it increases modulator pressure Engine vacuum acts in the opposite direction to decrease modulator or low engine vacuum high modulator pressure High engine vacuum and low modulator pressure TRUCK SUPP SERVICE 7 2 AUTOMATIC TRANSMISSION Bp W LP MAINTENANCE AND ADJUSTMENTS TRANSMISSION FLUID Draining and Refilling Transmission The oil pan should be drained and the strainer cleaned every 30 000 miles and fresh fluid added to obtain the proper lever on indicator For vehicles subjected to heavy city traffic during hot weather or in comme
20. 5 6 000 OHMS REMOVE GREEN amp WHITE LEADS FROM MODULE LESS THAN INFINITY REPLACE COIL W i 1000 SCALE PICK UP CONNECT qe OHMMETER FROM GROUND TO EITHER READS INFINITE X 1000 SCALE REPEAT STEPS 4 AND 5 WHILE MOVING N ADVANCE WITH SCREW RUNS SMOOTH z CONNECT OHMMETER ACROSS 2 LEADS READS 500 TO 1500 OHMS DRIVER IF READING IS STILL OK oo DOES NOT READ 500 15000HMs REPLACE COIL PICK UP CHECK MODULE WITH TESTER IF NOTOK REMOVE AND REPLACE MODULE TRUCK SUPP SERVICE 6Y 20 ENGINE ELECTRICAL HIGH ENERGY IGNITION SYSTEM V8 engine PROBLEM engine CRANKS but WILL NOT START CONNECTOR AUTO TRANS LEVER IN PARK J TEST LIGHT ON MANUAL TRANS I IGNITION x ON 2 CONNECT TEST LIGHT TO BAT LEAD TERM TEST LIGHT LEVER IN NEUTRAL TEST LIGHT REPAIR OFF LEAD OR CONNECTOR INSERT TEST LIGHT IN RED B WIRE TEST LIGHT ON e 9 REPAIR OR TEST vnd REPLACE AS NECESSARY NO START REMOVE A SPARK PLUG WIRE INSERT EXTENSION AND PERFORM SPARK TEST PROBLEM IS gt NOT IGNITION CRANK SYSTEM USING INSULATED PLIERS ENGINE HOLD SPARK PLUG WIRE 1 4 AWAY FROM ENG BLOCK WHILE CRANKING ENGINE EATENSION TRUCK SUPP SERVICE ENGINE ELECTRICAL 6Y 21 HIGH ENERGY IGNITION SYSTEM V8 engine
21. BOOSTER TEFLON RING HOUSING O RING RELIEF VALUE RETAINING RING O RING PISTON BOOSTER POWER SECTION Fig 7 Accumulator Components Integral Booster TRUCK SUPP SERVICE EE 5 U 3 Install a remote control starter switch so that engine can be cranked but not started CAUTION Whenever the engine is cranked remotely at the starter with a special jumper or other means the distributor primary lead must be disconnected from the negative post on the coil 4 Crank engine for 4 to 5 second intervals while pouring fluid into the reservoir 5 Fill reservoir and crank as in step 4 until system will no longer accept fluid It is normal that fluid may spill when cranking stops it is the result of air in the system trying to escape To prevent spilling crank engine 6 Remove remote control starter switch Reinstall distributor primary lead 7 Start engine and allow to run 2 seconds 8 Check and refill fluid reservoir if necessary 9 Start engine and depress the brake pedal several times while rotating the steering wheel from stop to stop 10 Turn engine off and then pump brake pedal 4 5 times to deplete accumulator pressure 11 Check and refill fluid reservoir if necessary 12 Repeat Steps 9 10 and 11 Install pump reservoir cap 13 Remove vehicle from hoist BRAKE PEDAL ADJUSTMENT All hydro boost equipped vehicles incorporate non adjustable brake pedal rod
22. CHEVROLET SERVICE and OVERHAUL MANUAL SUPPLEMENT FOREWORD This manual has been prepared as a supplement to the 1974 Light Duty Truck Service and Overhaul Manuals It covers in separate sections diagnosis maintenance adjustments service operations and overhaul procedures for the 1976 10 30 Series truck models Complete wiring diagrams for the vehicles covered in this manual will be found in the separate 1976 Truck Wiring Diagram booklet ST 352 76 Any reference to brand names in this manual is intended merely as an example of the types of lubricants tools mate rials etc recommended for use In all cases an equivalent may be used AII information illustrations and specifications contained in this literature are based on the latest product information avail able at the time of publication approval The right is reserved to make changes at any time without notice CHEVROLET MOTOR DIVISION General Motors Corporation DETROIT MICHIGAN IMPORTANT SAFETY NOTICE Proper service and repair is important to the safe reliable operation of all motor vehicles The service procedures recommended and described in this service manual are effective methods for performing service operations Some of these service operations require the use of tools specially designed for the purpose The special tools should be used when and as recommended It is important to note that some warnings against the use of s
23. Federal 0 8 Hg 15 p 15 5 Hg 8 RA4TX O 8 Hg 10 0 13 Hg Federal 0 4 Hg 18 7 Hg 4 R44TX 060 R45TS 045 12 1100 2800 O 10 Hg 15 17 Hg V 8 454 4BBL C 10 P U w RPO F44 C 10 Suburban C20 30 amp P 30 V 8 454 4BBL LF8 C 10 P U w o Cat Converter w RPO F44 C 10 Suburban C20 30 amp P 30 ectronically Governed 1112869 or None Application Federal 8 R45TS 045 R447 045 Calif 0 1100 0 6 Hg 8 BTC R44T 14 2809 20 15 Hg 045 20 4200 BATTERY Cold Crank Rate O F Watts Cranking Power 25 Amp Reserve Capacity Minutes 292 L 6 305 amp 350 V 8 454 V 8 amp RPO Option RPO RPO TP2 2500 275A 1 60 125 TRUCK SUPP SPECS SPECIFICATIONS 20 CLUTCH AND MANUAL TRANSMISSION SECTION 7M THREE SPEED SAGINAW Clutch Gear Retainer to Case Bolts Side Cover to Case Bolts Extension to Case Bolts Shift Lever to Shifter Shaft Bolts Lubrication Filler Plug Transmission Case to Clutch Housing Bolts Crossmember to Frame Nuts Crossmember to Mount Bolts 2 3 Cross Over Shaft Bracket Retaining Nut 1 Rev Swivel Attaching Bolt Mount to Transmission THREE SPE
24. If this value is not within 50 in Hg of the specified valve set point then the valve must be adjusted 6 To adjust the valve set point a Gently pry off the conical plastic cover b Turn the adjusting screw in clockwise to raise the set point or out counterclockwise to lower the set point value c Recheck the valve set point per steps No 3 and 5 d Repeat steps 6b and c as necessary to obtain the specified value within 50 in Hg 8 Reinstall plastic cover 9 If the valve cannot be adjusted it must be replaced Replacement Disconnect vacuum hoses at control valve Remove nut washer and control valve Reverse procedure to install and check operation of control valve TRUCK SUPP SERVICE THROTTLE LEVER ACTUATOR Fig 10 Check and Diagnosis 1 Disconnect valve to actuator hose at valve and connect to an external vacuum source equipped with a vacuum gauge 2 Apply 20 in Hg vacuum to actuator and seal off the vacuum source If vacuum gauge reading drops then actuator is leaking and must be replaced 3 To check actuator for proper operation a b Check throttle lever shaft and linkage to be sure that they operate freely without binding or sticking Start engine and run until warmed up and idle is stable with transmission in neutral or park Note idle rpm Apply 20 in Hg vacuum to the actuator Manually open the throttle slightly and allow to close against the extended actuator plunger
25. pom IF ALL AND REPLACE LIGHTS OFF GAUGES FUSE GENERATOR LIGHT ON TEST LIGHT FULLY BRIGHT CONNECT TEST LIGHT A TEST LIGHT GROUND TO NO 1 gt ek 1 2 BRIGHT GENERATOR TERMINAL D SHAPED TEST LIGHT HOLE 1 2 BRIGHT 4 GO TO STEP5 Te REGULATOR WITH SS REPLACE CRM VOLTAGE REGULATOR REPAIR GENERATOR TRUCK SUPP SERVICE 6Y 24 ENGINE ELECTRICAL CLUSTER Chart 2 SENER AT eae a CONNECTOR GENERATOR 1 PROBLEM generator light OFF ignition ON engine NOT RUNNING BULKHEAD CONNECTOR STEP SEQUENCE RESULT gt STOP B GENERATOR oA IF NEW A LIGHT ON GO TO RUSE STEP 2 BLOWS CHECK ALL IFALL A d IF FUSE OE INDICATOR LIGHTS LIGHTS OFF REPLACE GENERATO DOES STEP3 GAUGES FUSE Gut OFF NOT BLOW 2 CHECK FOR PINCHED OR 3 GROUNDED WIRE IN GAUGES CIRCUITS lt gt EM O0 PA GENERATOR FUSE BLOCK LIGHT ON GO TO REPAIR o STEP 3 IF NECESSARY REPLACE GENERATOR GAUGES FUSE LIGHT OFF Q 4 9 GENERATOR LIGHT ON 9 GO TO REPAIR OPEN IN o STEP 4 NO 18 PINK WIRE GENERATOR INDICATOR FEED WIRE LIGHT OFF GENERATOR LIGHT ON REPLACE 3 pst 3 STEP 5 CHECK GENERATOR IF NECESSARY N INDICATOR BULB AND GENERATOR SOCKET ASSY LIGHT OFF 5 GO TO STEP 6 DISCONNECT BROWN WHITE LIGHT ON WIRE GO TO STEP 7 GROUND NO 1 TERMINAL GENERATOR WIRE LIGHT OFF TRUCK SUPP S
26. 10 18 19 20 2l If pressure drops below 15 psi in 10 seconds the spring washer gasket may be leaking To check proceed to Step 11 If pressure does not drop proceed to Step 15 Remove Pressure Tester J 24460 from Adapter J 23699 Reconnect overflow hose to radiator neck nipple and carefully open the radiator cap thus releasing pressure from the radiator into the radiator reservoir tank Check spring washer gasket on the radiator cap This gasket seals between the cap and the top of the radiator filler neck If defective replace radiator cap Reconnect adapter per Step 8 and pump system to 15 psi and again check to determine if pressure drops below 15 psi in 10 seconds Tocheck cap and system holding pressure wiggle upper radiator hose to stabilize Hose Gauge J 23636 and set red washer against the movable handle Remove Pressure Tester J 24460 from Adapter J 23699 While system is under pressure examine all hoses hose connections radiator heater water pump and all gaskets for visible signs of leaking and repair or tighten as indicated After 5 minutes wiggle hose again and note position of movable handle If handle has not moved more than a 1 4 inch in 5 minutes cap is holding sufficient pressure If handle has moved more than a 1 4 inch check again for leaks repressurize per step 9 remove Pressure Tester J 24460 per Step 11 and insert hose in a glass of wa
27. CURB IDLE SCREW Fig 10 Model 4MV Quadrajet Carburetor THEORY OF OPERATION FLOAT SYSTEM FIG 2Q The float system consists of a float bowl pontoon assembly made of a closed cellular plastic material float hinge pin a float needle valve and seat and a float valve pull clip Fuel from the engine fuel pump enters the carburetor fuel inlet passage and passes through the filter and needle seat As fuel fills the float bowl to the prescribed fuel level the float pontoon rises and forces the fuel inlet valve closed shutting off all fuel flow As fuel is used from the float bowl the float drops and allows more fuel to enter the float bow until the correct fuel level is reached This cycle continues constantly maintaining a positive fuel level in the float bowl A float needle pull clip fastened to the float valve hooks over the center of the float arm Its purpose is to assist in lifting the float valve off its seat whenever fuel level is low A plastic filler block is Jocated in the top of the float bowl in the area just above the fuel inlet This block prevents fuel slosh on severe brake applications or turning maneuvers This maintains a constant fuel level during these maneuvers to prevent stalling The carburetor float bow is internally vented The internal vent tubes are located in the primary bore section of the carburetor air horn just above the float chamber The purpose of the internal vent is to balance inco
28. EXHAUST MANIFOLD ASSEMBLY Removal 1 Remove air cleaner 2 Remove power steering pump and or A LR pump brackets if so equipped Remove EFE valve bracket Disconnect throttle controls and throttle return spring Disconnect exhaust pipe at manifold flange Remove manifold attaching bolts then remove manifold and discard gasket 7 Check for cracks in manifold assembly Installation 1 Clean gasket surfaces on cylinder head and mainfold 2 Position new gasket on exhaust manifold 3 Install manifold assembly bolts while holding manifold assembly in place 4 Clean oil and torque all manifold to cylinder head bolts and nuts to specifications fig 1A LBS FT e 9 Les rr 2 e M e Fig 1A Exhaust Manifold to Cylinder Head Bolt Tightening Sequence and Torque 5 Connect exhaust pipe to manifold 6 Connect throttle controls and throttles return spring 7 Install air cleaner start engine and check for leaks OIL PAN Removal Fig 4L 1 Disconnect battery negative cable 2 Remove radiator upper mounting panel 3 Place a piece of heavy cardboard between fan and radiator 4 Raise vehicle on hoist 5 Drain engine oil 6 Remove starter on manual transmission equipped vehicles 7 Remove either flywheel underpan or converter housing underpan and splash shield 8 Remove through bolts from engine front mounts 9 Use a jacking device and raise engine approximatel
29. NUMBER Choke Fast Idle A Automatic Trans Setting INDEX 1NR INDEX 1NR TRUCK SUPP SPECS SPECIFICATIONS 14 CARBURETOR ADJUSTMENTS 1MV Carburetor NUMBER ETE Choke Rod Primary Auxiliary Float Metering Choke A Automatic Trans Fast Idle Vacuum Vacuum Unloader Level Rod Setting M Manual Trans Cam Break Break 170560024 11 32 265 17056003 M 11 32 080 145 180 wo 17056004 11 32 M A 4MV Carburetor NUMBER Choke Rod Air Vacuum A Automatic Trans Fast Valve Break M Manual Trans Idle Dashpot Cam 7045213 A M 015 7045214 A M 015 7045215 015 7045216 015 Refer j 7045225 to 7045229 A 295 Section 7045583 A M 295 6 for 7045585 A Choke 7045586 A M 7045588 295 Adjust 7045589 A 17056212 A M 17056217 A TRUCK SUPP SPECS SPECIFICATIONS 15 CARBURETOR ADJUSTMENTS Continued M4MC Carburetor NUMBER Choke Rod Un Choke A Automatic Trans Level Fast Valve loader Set Idle Dashpot ting Cam u 17056208 A 9 32 120 325 17056209 M 325 015 3NL 17056218 A 5 16 325 015 7 8 2NL 17056219 M 5 16 325 015
30. P Dua Salisbury 7500 101 2 p Fig 1 Axle Chart Fig 2 Closed and Open Positions CLOSED POSITION Except cao Dual Salisbury 7500 TRUCK SUPP SERVICE 4 2 REAR SUSPENSION PROPSHAFT AND AXLE Fig 3 Lubrication Tools REAR SPRING U BOLT Rear spring U bolt and anchor plate installation must be as shown in figure 4 BUSHING REPLACEMENT Rear Spring Front Eye Heavy duty leaf springs C20 and C30 trucks use a staked in place front eye bushing Before this bushing is pressed out of the spring the staked locations must be straightened with a chisel or drift After a new bushing is installed it must be staked in three equally spaced locations Refer to page 4 6 in the 1974 Light Duty Truck Service Manual NOTE U BOLTS MUST BE LOCATED AROUND THE AXLE TUBE SO THAT THE LEGS PASS THE SPRING SEAT WITHIN 060 Fig 4 U Bolt Installation PROPSHAFT Universal Joint Repair Two methods of retaining trunnions to universal joint yokes may be used Each requires a different repair procedure The snap ring method 18 described on pages 4 9 through 4 10 of the 1974 Light Duty Truck Service Manual An injection molded plastic retainer ring Is used on other universal Joints For this type joint the following repair procedure should be used Disassembly NOTE Never clamp propshaft tube in a vise as the tube may be dented Always clam
31. socket of fuse panel Replacement Fig 7 3 Disconnect electrical connector to instrument panel l Disconnect electrical connector from LPS Lamps harness socket of fuse panel 4 Remove strap securing buzzer to instrument panel harness 5 Install replacement headlamp warning buzzer in reverse HEADLAMP WARNING sequence of removal BUZZER SEAT BELT WARNING SYSTEM PLUG TAN WIRE CONNECTOR 1976 C K type light duty trucks have a non sequential INTO CAVITY timer controlled seat belt warning system This new system MARKED IGN will have an instrument panel warning light that will illuminate every time the ignition switch is turned on whether or not the driver s seat belt is buckled but will automatically go off after 4 8 seconds The buzzer will also be controlled by the 4 8 second timer but will operate only PLUG RED WIRE if the driver has not buckled up prior to turning on the CONNECTOR ignition If no attempt is made to buckle up after turning on INTO CAVITY the ignition the buzzer will also shut off automatically after MARKED LPS 4 8 seconds A trouble shooting diagnostic chart and wiring schematic are shown in Figures 8 and 9 Fig 7 Headlamp Warning Buzzer TRUCK SUPP SERVICE 32 835 9415 32nH1 sapuiway 3198 eas g sisouDei SEAT BELT REMINDER LIGHT BUZZER DIAGNOSIS REMINDER LIGHT NE BUZZER NORMAL CHECK CONNECTION OF LAMP GROUND CIRCUIT TO INSTRU MENT PAN
32. ACCUMULATOR PISTON Fig 9B Front Accumulator Assembly Exploded from the forward clutch housing c Models CG and CR Remove five 5 radial grooved composition faced four 4 thick 0915 flat steel and one 1 waved steel clutch plates from forward clutch housing d Model CL Remove five 5 radial grooved composition faced and five 5 thick 0915 flat steel clutch plates U notch four 4 composition and three 3 thin 0775 flat steel clutch plates starting with waved plate and alternating composition faced and steel clutch plates Models CJ CM CP CT and CZ Install one 1 waved steel plate with U notch five 5 composition faced and four 4 thin 0775 flat steel clutch plates starting with waved plate and alternating composition faced and steel clutch plates Models CG and CR Install one 1 waved steel plate with U notch five 5 composition and four 4 thick 0915 flat steel clutch plates starting with waved plate and alternating composition faced and steel clutch plates Model CL Install five 5 thick 0915 flat steel and five 5 composition faced clutch plates starting with flat steel and alternating composition faced and flat steel clutch plates NOTE The model CL forward clutch composition faced plates are different from the other models Refer to parts catalog book for correct usage TRUCK SUPP OVERHAUL DIRECT CLUTCH AND INTE
33. Install new pins in front cylinder half if previously removed Install front suction reed plate on front cylinder half Align with dowel pins suction ports oil return slot and discharge cross over tube Fig 58 Install front discharge valve plate assembly aligning holes with dowel pins and proper openings in front suction reed plate Fig 59 Front discharge plate has a large diameter hole in the center Fig 60 Coat sealing surfaces on webs of compressor front head casting with 525 viscosity refrigerant oil Determine exact position of front head casting in relation to dowel pins on internal mechanism Mark position of dowel pins on sides of front head assembly and on sides of internal mechanism with a grease pencil Carefully lower front head casting into position Fig 62 making certain that sealing area around center bore of head assembly does not contact shaft as Qs 1 BUSHING Oil Return Slot Front Suction Reed Plate SUPPORT BLOCK J 21352 Discharge Crossover Tube u t Fig 58 Installing Front Suction Reed head assembly is lowered Do not rotate head assembly to line up with dowel pins as the sealing areas would contact reed retainers 8 Generously lubricate new O ring and angled groove at lower edge of front head casting with 525 viscosity refrigerant oil and install new O ring into groove Fig 62 9 Coat inside machined surfaces
34. Install rear suction reed over dowel pins with slot TOWARDS sump Install rear discharge valve plate assembly over dowel pins with reed retainers Position inner oil pump gear over shaft with previously applied identification mark UP Position outer oil pump gear over inner gear with previously applied identification mark UP and when standing facing oil sump position outer gear so that it meshes with inner gear at the 9 o clock position and resulting cavity between gear teeth is then at 3 o clock position Fig 65 Generously oil rear discharge valve plate assembly with 525 viscosity refrigerant oil around outer edge where large diameter O ring will be placed Oil the valve reeds TRUCK SUPP OVERHAUL 1 24 AIR CONDITIONING COMPRESSOR 21 22 23 24 Oil Intake Tube Hole Fig 64 Installing Oil Pick Up Tube pump gears and area where sealing surface will contact rear discharge valve plate Using the 525 oil lubricate new head to shell O ring and install on rear discharge valve plate in contact with shell Fig 66 Install suction screen in rear head casting using care not to damage screen Coat sealing surface on webs of compressor rear head casting with 525 viscosity refrigerant oil Install rear head assembly over studs on compressor shell The two lower threaded compressor mounting holes should be in alignment with the compressor sump Make certain that suction screen does not drop
35. Power Piston Remover and Installer Power Brake Retainer and Installer Bushing Retainer Socket Height Gauge Power Cylinder Seal Installer Seal Installer and Protector Power Cylinder Holding Fixture Fig 10 Special Tools J 22839 J 22893 J 23101 J 23175 J 23188 J 24551 J 24553 J 24554 J 24569 J 9504 Front Plate Holding Fixture Booster Separating Adapter Power Piston Holding Tool Control Valve Installer Secondary Bearing Protector Piston Installer Input Rod Seal Installer Socket Pedal Push Rod Remover Power Cylinder Spanner Wrench TRUCK SUPP OVERHAUL SECTION 6 ENGINE REPAIR PROCEDURES CAMSHAFT Inspection When checking the camshaft for alignment using the V block method the dial indicator will indicate the exact amount the camshaft is out of true If it is out more than 001 dial indicator reading the camshaft should be replaced REPAIRS Piston Selection Piston to bore clearance for all engines is increased by 0010 for 1976 Refer to page 6 35 fig 74 in the 1974 Overhaul Manual TRUCK SUPP OVERHAUL SECTION 6M CARBURETOR CONTENTS OF THIS SECTION Introduction Rochester IMV Rochester 2GC Rochester 4MV Rochester M4MC M4ME Special Tools eese 6 5 6 11 INTRODUCTION A carburetor is designed
36. SCREW AND LOCKNUT for Fig 2 Glass Run Channel Adjustment Together this allows proper alignment of the glass to the rear glass run channel for full up and down travel Refer to pages 14 1B 15 of the 1974 manual REAR DOOR CHECK STRAP Model 06 Figure 3 shows the cloth check strap used for rear doors The door may be completely opened by removing the strap pin from the bracket The bracket attaches to the pillar with three screws the strap is fastened to the door panel with two screws and an attaching bar Refer to page 1B 18 of the 1974 manual TRUCK SUPP SERVICE 1B 2 BODY Fig 3 Rear Door Hinges and Strap REAR DOOR STRIKER AND WEDGE ADJUSTMENTS Figure 4 illustrates the rear door latch strikers and door wedges Be sure that adjustments are as shown to insure proper latching of the rear doors Refer to page 1 18 figure 48 of the 1974 manual ENDGATE DISASSEMBLY Model 06 Refer to page 1B 20 of the 1974 Light Duty Truck Service Manual STRIKER ADJUSTMENT 17 03 11 64 SECONDARY LATCHED POSITION 04 IN SECONDARY LATCHED POSITION OR 010 TO TO 050 INTERFERENCE UN FULL LATCHED POSITION STRIKER lt lt ADJUSTMENT Fig 4 Wedge and Striker Adjustments Step 10 defines the proper method of removing the regulator on an electric powered window The following CAUTION emphasizes the need for follo
37. SERVICE OPERATION CARBURETOR REPLACEMENT FIG 190 Removal Flooding stumble on acceleration and other performance complaints are in many instances caused by presence of dirt water or other foreign matter in carburetor To aid in diagnosis carburetor should be carefully removed from engine without draining fuel from bowl Contents of fuel bowl may then be examined for contamination as carburetor is disassembled Check filter 1 Remove air cleaner and gasket 2 Disconnect fuel and vacuum lines from carburetor 3 Disconnect fresh air hose and choke hose from choke system 4 Disconnect accelerator linkage 5 If equipped with automatic downshift cable disconnect cable 6 Remove carburetor attaching bolts and remove carburetor 7 Remove insulator Installation It is good shop practice to fill carburetor bowl with a small amount of unleaded fuel before installing carburetor This reduces strain of starting motor and battery and reduce the possibility of backfiring while attempting to start engine The carburetor float and intake needle and seat can also be CHOKE BOSS ON CHOKE INTO INBOARD HOLE Fig 190 Model 4MV Quadrajet Carburetor Choke checked Operate throttle lever several times and check discharge from pump jets before installing carburetor 1 Clean throttle body and intake manifold sealing surfaces 2 Install new insulator 94 Position carburetor over intake manifold and inst
38. The choke system is equipped with an unloader feature to partially open the choke valve should the engine become flooded or loaded To unload the engine the accelerator pedal must be depressed so that the throttle valves are held wide open A tang on the throttle lever contacts the fast idle cam and through the choke rod forces the choke valve slightly open This allows extra air to enter the carburetor bores and pass on into the engine manifold to lean out the fuel mixtures so the engine will start MAINTENANCE AND ADJUSTMENT IDLE SPEED ADJUSTMENT 1 With engine at normal operating temperature air cleaner on choke open and air conditioning OFF connect a tachometer to engine 2 Set parking brake and block drive wheels 3 Disconnect vacuum advance hose at distributor and plug hose 4 Start engine check timing and adjust as required Reconnect vacuum advance hose 5 With automatic transmission in Drive or manual transmission in Neutral turn idle speed screw to specified rpm 6 Shut off engine and remove tachometer 7 Remove blocks from drive wheels IDLE MIXTURE The idle mixture is factory preset and idle mixture screws are capped with plastic limiter caps The cap permits screw to be turned about one turn leaner clockwise without breaking cap The idle mixture is set to achieve the smoothest idle while maintaining emission levels within standards prescribed by Federal Law At major carburetor overhaul th
39. The main venturi is 1 5 16 in diameter and the throttle bore is 1 11 16 Fuel flow through the main metering system is controlled by a main well air bleed and a variable orifice jet A power enrichment system is used to provide good performance during moderate to heavy accelerations and at higher engine speeds On a vehicle with automatic transmission and air conditioning the idle system incorporates a hot idle compensator A T only to maintain smooth engine idle during periods of extreme hot engine operation The model MV incorporates an automatic choke system The vacuum diaphragm units are mounted externally on the air horn and connect to the thermostatic coil lever through a connecting link The automatic choke coil is manifold mounted and connects to the choke valve shaft by a rod An integral pleated paper fuel inlet filter is mounted in the fuel bowl behind the fuel inlet nut to give maximum filtration of incoming fuel The Monojet carburetor has an aluminum throttle body for decreased weight and improved heat distribution and a thick throttle body to bowl insulator gasket to keep excessive TRUCK SUPP SERVICE 6M 2 ENGINE FUEL CHOICE SHAFT AND LEVER ASSEMBLY PRIMARY CHOKE VACUUM BREAK AUXILIARY CHOKE DIAPHRAGM VACUUM BREAK DIAPHRAGM IDLE STOP SOLENOID THROTTLE LEVER FAST IDLE CAM Fig 1 1 Monojet Carburetor engine heat from the float bowl The carburetor has internally balanced v
40. in Ib in tb in lb in Ib lb in Ib in Ib in Ib ini Jb END GATE 06 Hinges Hinge to Body 35 ft Hinge to End 20 ft Support Cable 18 25 ft Torque Rod Silencer Bracket 40 in End Support Bracket 90 in Latch Assembly to End Gate 20 ft Latch Remote Control Assembly to End Gate 40 in AGCCeSSICOVOT 18 in Outside Handle 55 in Glass Channel 4 dud vuv A S 45 in TAILGATE 03 63 with E63 Trunnion Assembly 18 ft Linkage and Striker Assembly Support 25 in TAILGATE 03 63 with E62 Trunnion Assembly 35 ft Chain Support Assembly 90 in SEATS Front Bench Seat 03 06 63 Adjuster to Seat 155 in Adjuster to Floor 25 ft Front Bucket Type 14 03 Driver 18 ft Adjuster to Floor 25 ft Passenger 03 18 ft Support to Floor Front 25 ft Support to Floor Rear 40 ft Passenger 14 Latch Support to Seat Rear 18 ft Striker to Floor Rear 25 ft Support Upper to Seat Front 18 ft Support Lower to Floor Front 25 ft Support Upper to Support
41. over both end seals of paper element as BAND SHOWN AIR CLEANER PAPER FILTER PORTION DE NOTE Polyurethane Bond must completely cover the outer screen surface of paper element es shown POLYWRAP Z AIR CLEANER ELEMENT s BAND SHOWN PAPER FILTER PORTION p OF POLYWRAP AIR i N CLEANER ELEMENT Fig 10C Polywrap Air Cleaner Element OO rss r s I OA WIO A sr EFE IJECLL II CILICIIL UCC CCCE SS 4 Clean bottom section of air cleaner and inspect cover seal fro tears or cracks Replace seal if damaged 5 Inspect band for tears and replace if damaged 6 If band is serviceable wash in kerosene or mineral spirts and squeeze out excess solvent fig 11C NOTE Never use a hot degreaser or any solvent containing acetone or similar solvent also never shake swing or wring the element to remove excess solvent as this may tear the polyurethane material Instead squeeze the excess solvent from the element 7 Dip band into light engine oil and squeeze out excess oil 8 Install band around outer surface of new paper element 9 Install element in bottom section of air cleaner with either end up 10 Install air cleaner cover Do not over torque wing nut s AIR CLEANER Refer to figures 12C and 13C for air cleaner used with in line L6 engine Refer to figure 14C for air cleaner used on CK truck with 350 400 V8 engine Refer to figure 15
42. r I RUNS SMOOTH VISUALLY INSPECT REPAIR AS L A gt H lt FOR MOISTURE DUST NECESSARY DISCONNECT CRACKS BURNS ETC RUNS ROUGH 3 WIRE CONNECTOR a Hu s doo EITHER TEST J READS 6 000 2 TO 30 000 OHMS r _ k gt CTS 4 RUNS SMOOTH CONNECT OHMMETER BOTH TESTS REPLACE READ INFINITY COIL 7 RUNS ROUGH REMOVE GREEN amp WHITE LEADS FROM MODULE 1 than INFINITY REPLACE COIL M x1000scALE PICK UP 9 RUNS ROUGH OHMMETER FROM GROUND TO EITHER READS INFINITE LEAD X 1000 SCALE CONNECT OHMMETER ACROSS 2 LEADS WHILE MOVING VAC ADVANCE WITH SCREW DRIVER IF READING IS STILL OK DOES NOT READ 500 1500 0HMs REPLACE COIL PICK UP READS 500 TO 1500 OHMS CHECK MODULE WITH TESTER IF NOT OK REMOVE AND REPLACE MODULE TRUCK SUPP SERVICE ENGINE ELECTRICAL 6Y 23 Chart 1 PROBLEM generator light ON engine RUNNING GENERATOR BELT SEQUENCE RESULT STOP FUSE BLOCK GENERATOR LIGHT OFF REPLACE IF Y NECESSARY CHECK ADJUST START ENGINE GENERATOR TENSION TO 80 LBS GENERATOR LIGHT ON DIM OR BRIGHT CHECK ALL x GENERATOR INDICATOR LIGHT OFF LIGHTS CHECK FOR CAUSE START ENGINE IGNITION ON
43. 0027 70035 Max PISTON RING 0020 0040 0012 0032 0017 0032 Hi Limit Production 001 010 020 018 025 010 020 Service Hi Limit Production 01 Groove Production 005 Max 005 0055 002 007 0005 0065 1 1 5 3 6 2 4 1 8 4 3 6 5 7 2 3 9995 4 0025 4 2495 4 2525 001 Max 3 8745 3 8775 0005 0005 0015 0025 Production 0012 0027 Clear ance Groove 010 020 ZOTUA Q RE Service Hi Limit Production 001 I Em Production 015 055 010 030 p Hi Limit Production 01 PISTON PIN Diameter 9270 9273 9895 9898 00015 00025 00025 00035 Clearance 001 Fit in Rod 0008 0016 Interference TRUCK SUPP SPECS SPECIFICATIONS 10 CRANKSHAFT 1 1 2 3 4 2 1485 2 7494 5 di 2 4484 2 4493 2 iameter 2 2983 2 2993 2 7481 2 1490 5 2 4479 2 4488 5 Main 2 7418 2 7488 Service 001 Max Out of Production 0002 Max Round Service 001 Max 1 All All 0008 0020 1 2 3 4 Main 0003 0008 3234 0013 0025 Bearing pe 0011 0023 5 Clearance 0029 0034 5 0024 0040 0017 003
44. 2 18 in Side Vent Screws and Spacers 25 in Lower Vent Channel Bolts 40 in Side Rear Door Run Channel Front Upper to 40 in Rear Upper to Door 20 in Front and Rear Lower to Door 85 in Lock Lever to Door 85 in Rear Door Lock Striker 06 95 in Rear Door Latch L H and R H to Door 06 85 in Rear Door Latch Control Assembly to Door 06 Upper Assembly 85 in Lower Assembly 90 in Rear Door Weatherstrip 06 18 in Cneck Arm Strap to Door 45in Bracket to Body 451 END GATE 14 16 Hinges Body Half and Gate 35 ft Support Assembly Body to End 25 ft Torque Rod Retainer Assembly 85 in Anchor Assembly 18 ft Latch Assembly to End Gate 85 in Latch Control Assembly to End Gate 40 in Access CoVer su esos ee rm 18 in Handle to Latch Control Assembly 45 in Glass Channel Assembly to End Gate 85 in Cap Assembly to Channel Assembly 40 in Striker Body Mounted 18 ft BODY SECTION 1B C AND K MODELS in Ib in lb in Ib in Ib in Ib in Ib Ib in Ib in Ib lb in Ib in Ib in Ib Ib Ib in Ib in Ib in Ib in Ib
45. 22R Installing Front Bearing Turn shift rail until detent notches in rail face bottom of case Insert a phillips screwdriver in detent bore to depress lower detent plug and push shift rail into rear bore Move rail inward until detent plug engages forward notch in shift rail second gear position Secure fork to rail with setscrew and move second third synchronizer to Neutral centered position MANUAL TRANSMISSION 7M 9 Fig 24R Installing Speedometer Retainer and Gear 20 Install interlock plug in detent bore With Second Third 21 synchronizer in Neutral position top of plug will be slightly below surface of First Reverse shift rail bore Move first reverse synchronizer forward to first gear position Place First Reverse shifter fork in groove of sleeve Be sure setscrew hole in fork is facing up Rotate fork into position in case engage fork in shifter fork shaft and insert First Reverse shift rail through rear case bore and shifter fork 22 Turn shift rail until detent notches in rail face upward Move rail inward until setscrew hole in fork and setscrew bore in shift rail are aligned Secure fork to rail with setscrew and place First Reverse sleeve and gear into Neutral centered position fig 20R TRUCK SUPP OVERHAUL 7M 10 MANUAL TRANSMISSION 23 24 25 26 27 28 29 30 Install large snap ring on front bearing Install front bearing on clutch gear shaft by hand drive
46. 5F Fig 5F Removing Rear Output Bearing Retaining Ring 4 Pull or tap bearing from housing 5 To remove the front bearing insert a long drift through rear opening and drive bearing from housing Fig 6F Remove and discard rubber seal Assembly 1 Position rear bearing in housing and tap into place 2 Install snap ring retaining bearing to case NOTE Retaining Ring is a select fit Use service ring size or D as required to provide tightest fit 3 Position rear seal to bore and drive into place using tool J 22388 Fig ors other suitable tool until approximately 1 8 to 3 16 below housing face 4 If the vent seal falls out or is knocked out during disassembly reinstall new seal or thoroughly clean and dry the area and re cement the old seal in place TRUCK SUPP OVERHAUL 7M 20 MANUAL TRANSMISSION Assembly 1 Position rubber seal in bearing bore Use grease to hold in place Position roller bearing in bore and press into place until bearing bottoms out in housing 2 Position new O ring on housing ASSEMBLY OF TRANSFER CASE FIGS 1F 1 Place range box on blocks with input gear side toward bench 2 Position range box to transfer case housing gasket on input housing 3 Install lockout clutch and drive sprocket assembly on the input shaft assembly NOTE A 2 band clamp may be installed on end of shaft to prevent loosing bearings from clutch assembly 4 Install input sh
47. Charging Station Oil Inducer Goggles 7 16 20 90 Gauge Line 3 8 24 Adapter 7 16 20 Straight Gauge Line 3 8 Adapter Leak Detector Puller Puller Pilot Refrigerant Can Valve Side Tap Refrigerant Can Valve Top Tap SPECIAL TOOLS J 5421 02 J 5403 J 6435 J 9396 J 25030 J 9403 J 9399 J 9401 J 9480 01 J 9392 J 23128 Fig 96 Air Conditioning Special Tools 28 30 Pocket Thermometers 2 No 21 Snap Ring Pliers No 26 Snap Ring Pliers Compressor Holding Fixture Compressing Fixture Clutch Hub Holding Tool 9 16 Thin Wall Socket Hub and Drive Plate Assembly Remover Hub and Drive Plate Assembly Installer Seal Remover Seal Seat Remover 9398 J 9481 1 8092 J 21352 241 5139 1 9432 1 9553 01 J 21508 J 22974 J 9625 J 9402 32 Pulley Bearing Remover Pulley and Bearing Installer Handle Internal Assembly Support Block Oil Pickup Tube Remover Needle Bearing Installer Seal Seat O Ring Remover Seal Seat O Ring Installer Shaft Seal Protector Pressure Test Connector Parts Tray TRUCK SUPP OVERHAUL SECTION 3 FRONT AXLE K10 K20 FRONT AXLE INNER OIL SEAL INSTALLATION TOOL The procedure for oil seal replacement on page 3 1 of the 1974 Overhaul Manual should be revised to include special tool J 25111 for installing the oil seals The seals are illustrated as item 28 in figure 1 below Fig 1 Inner Oil S
48. Do not use fuses of higher amperage rating than those recommended above The following wiring harnesses are protected by a fusible link which is a special wire incorporated in the circuit ignition horn and headlamp hi beam indicator circuits Should an electrical overload occur this wire will fail and prevent to the major harness CIRCUIT BREAKERS Device or circuit protected Models Amperes Location Headlamp and parking Light lamp circuit 15 Switch Dash Tailgate window motor C K 30 forward side Dash Rear A C C69overhead G 15 forward side e e S S SIE TRUCK SUPP SPECS LAMP BULB DATA C K P TRUCK Used in Quantity Trade Power Dome lamps Cab 1 1003 15 CP Blazer Jimmy amp Suburban 1 211 2 12 CP Oil Pressure indicator lamp 1 168 3 CP Generator indicator lamp 1 168 3 CP Instrument cluster lamps 5 168 3 CP Headlamp beam indicator lamp 1 168 3 CP Lamp assembly tail amp stop lamp 2 1157 3 32 License lamp4 1 67 4 CP Directional signal front park lamps 8 2 1157 3 32 Head Lamps 2 6014 50 60W Temperature indicator lamp 1 168 3 P Directional signal indicator lamp 2 168 3 Clearance and marker lamps 4 168 3 CP Roof marker lamps 5 194 2 Brake Warning Indicator 1 168 3 CP Transmission Control 1 1445 0 7 CP Backing lamp 2 1156 32 CP Heater or A C 1 1445 0 7 CP Corner marker lam
49. Exercise personal care in cutting the piston ring for removal Clean the piston and piston ring grooves with a recommended cleaning solvent and blow the piston dry with dry air Trichlorethylene stoddard solvent kerosene or equivalent Set the piston on end on a clean flat surface and install the Ring Installer Guide J 24608 2 on the end of the piston Fig 46 J 24608 5 RING INSTALLER J 24608 2 RING INSTALLER GUIDE J 24608 3 O RING 4 Install a Teflon ring on the Ring Installer Guide J 24605 2 as shown in Fig 46 with the dished or dull side down and glossy side up Push the Ring Installer J 24608 5 down over the Installer Guide J 24608 2 to install the Teflon ring in the piston ring groove Fig 47 If the Teflon ring is slightly off position in the ring groove it can be positioned into place by fingernail or blunt edged tool that will not damage the piston The Ring Installer J 24608 5 will retain the Installer Guide J 24608 2 internally when the Teflon ring is installed on the piston Remove the Installer Guide from the Ring Installer and DO NOT STORE THE INSTALLER GUIDE IN THE RING INSTALLER as the Ring Installer Segment Retainer O Ring J 24608 3 will be stretched and possibly weakened during storage This could result in the O Ring J 24608 3 not holding the Ring Installer segments tight enough to the Installer Guide J 24608 2 to properly install the Teflon ring on the piston Lubricat
50. Flange Lock Nut Seal Front Output Yoke Dust Shietd Front Output Shaft Bearing Retainer Seal Front Output Shaft Bearing Retainer Front Output Shaft Bearing Bearing Outer Ring Bearing Retainer Gasket Front Output Shaft Rear Bearing Front Output Rear Bearing Retainer Cover Gasket Front Output Rear Bearing Retainer Orive Shaft Sprocket Drive Chain Retaining Ring Sliding Lock Clutch Lockout Shift Rail Shift Fork Retaining Pin Lockout Shift Fork Lockout Clutch Spring Spring Washer Cup Front Side Gear Front Side Gear Bearing and Spaces 123 Bearings Req d Differential Carrier Assembly 132 Bearings Req d Rear Output Shaft Roller Bearings 15 Req d Rear Output Shaft Speedometer Drive Gear Rear Output Shaft Front Roller Bearing Oil Pump 0 Ring Seal Rear Output Housing Gasket Rear Output Housing Front 0 Ring Sea Rear Output Housing Rear Shim Pack Bearing Retainer Rear Output Rear Bearing Rear Output Shaft Seal Rear Output Flange Rear Output Shaft Rubber Seal Flange Nut Fig 2F 2 Transfer Case Exploded View TRUCK SUPP OVERHAUL 15 16 12 18 19 INPUT GEAR FRONT OUTPUT SHAFT ASSY HOUSING RANGE SELECTOR COUNTER GEAR HOUSING Fig 3F Front View of Transfer Case LOCKOUT CLUTCH REAR OUTPUT IFT RAIL POP HOUSING SH OPPET PLUG RANGE SELECTOR SHIFTER SHAFT CHAIN HOUSING REAR OUTPUT FRONT OUTPUT SHAFT ASSY BEARING REAR COVER Fig
51. G21306 6400 Base JB5 G31005 1 110 6400 7100 Base JB6 6400 8100 J55 JB7 G31305 125 6600 7400 Base JB6 6600 8400 J55 JB7 G31306 6600 7400 Base JB6 6600 8400 J55 JB7 G31303 6400 8400 Base JB7 8900 455 JB8 G31603 146 8900 10000 Base JB8 TRUCK SUPP SERVICE o ae eel 5 4 BRAKES BRAKE SYSTEM APPLICATION continued MERCHANDIZING BRAKE MODEL TON RATING WHEELBASE GVW RATING OPTION SYSTEM P10542 1 2 102 6200 Base JB5 P20842 3 4 125 6800 Base JB6 6800 8000 J55 JB7 P21042 133 6800 Base JB6 6800 8000 J55 JB7 P30842 1 125 7600 8200 Base JB7 7600 10000 J55 JB8 12000 14000 H22 or H23 JB9 P30832 7600 12500 Base JB8 P31042 133 7600 8200 Base JB7 7600 10000 J55 JB8 12000 14000 H22 or H23 JB9 P31132 137 7600 12500 Base JB8 P31432 158 5 7600 12500 Base JB8 14000 HF7 or HF8 JB9 P31442 157 7600 8200 Base JB7 7600 10000 J55 JB8 12000 14000 H22 or H23 JB9 P31832 178 14000 Base JB9 TRUCK SUPP SERVICE BRAKES 5 5 STANDARD BRAKES The 1976 Light Duty Truck standard brake components are essentially the same as those described in the 1974 Light Duty Truck Service Manual Design modifications differing from the 1974 manual are outlined on the following pages FRONT DISC BRAKE Front disc brake rotors do not incorporate an anti squeal groove in the disc pad contact surfaces fig 1 BRAKE PEDAL ADJUSTMENT brake pedal push rods are non adjustable on 1976 models except Motor Home Chassis Units see
52. Improper starting orocedure used No fuel in gas tank Choke valve not closing sufficiently when cold Choke valve or linkage binding or sticking No fuel in carburetor Engine Flooded NOTE To check for flooding remove the air cleaner with the engine off and look into the carburetor bore Fuel will be dripping off nozzle and or the carburetor will be very wet Carburetor flooding CORRECTIVE ACTION Check proper starting as outlined in the owner s manual Add fuel Check fuel gauge for proper operation Adjust the choke coil rod Realign the choke valve or linkage as necessary f caused by dirt and gum clean with automatic choke cleaner Do not oil choke linkage If parts are replaced check adjustments 1 Remove fuel line at carburetor Connect hose to fuel line and run into metal container Remove the high tension coil wire from center tower on distributor cap and ground Crank over engine if there is no fuel discharge from the fuel line check for kinked or bent lines Disconnect fuel line at tank and blow out with air hose reconnect line and check again for fuel dis charge f none replace fuel pump Check pump for adequate flow as outlined in service manual 2 f fuel supply is o k check the following a Inspect fuel filter If plugged replace b If filter is o k remove air horn and check for a bind in the float mechanism or a sticking float needle If o k adjust float as specifie
53. Install coil cover onto distributor cap and secure with three screws Ignition Coil 6 Cylinder Removal Fig 5i 1 Disconnect ignition switch to coil lead at coil 2 Disconnect coil to distributor leads at coil 3 Remove 4 screws securing coil to side of engine and remove coil Installation Fig 1 Install coil to side of engine with 4 screws 2 Connect coil to distributor leads at coil 3 Connect ignition switch to coi lead at coil TRUCK SUPP SERVICE 6Y 16 ENGINE ELECTRICAL SPRING VACUUM UNIT HOUSING WASHER GEAR CONNECTOR Fig 10i Exploded View of 8 Cylinder HEI Distributor TRUCK SUPP SERVICE DIAGNOSIS ENGINE ELECTRICAL 6Y 17 HIGH ENERGY IGNITION SYSTEM L 6 engines PROBLEM engine CRANKS but WILL NOT START AUTO TRANS LEVER IN PARK MANUAL TRANS IGNITION ON LEVER IN NEUTRAL REMOVE A SPARK PLUG WIRE INSERT EXTENSION AND PERFORM SPARK TEST USING INSULATED PLIERS HOLD SPARK PLUG WIRE 1 4 AWAY FROM ENG BLOCK WHILE CRANKING ENGINE IGNITION OFF CONNECT TEST LIGHT TO BAT LEAD REPAIR OR REPLACE AS NECESSARY ENGINE REMOVE CAP ASSY Sp VISUALLY INSPECT FOR MOISTURE DUST CRACKS BURNS ETC r I Qi REPAIR AS L NECESSARY PICK UP COIL RESULT TEST LIGHT PROBLEM IS NOT IGNITION SYSTEM CHECK eFUEL SYSTEM ePLUGS STARTS s H NO START TRUCK SUPP S
54. Note engine rpm Release and reapply 20 in Hg vacuum to actuator and note rpm to which engine speed increases do not assist actuator If rpm obtained in step 3d is not within 150 rpm of that obtained in step 3c then the actuator plunger may be binding due to dirt corrosion varnish etc or actuator diaphragm may be too weak If binding is not indicated or cannot be corrected then the actuator must be replaced Release the vacuum from the actuator and the engine speed should return to within 50 rpm of the idle speed noted in step 3b If it does not the plunger may be binding due to dirt corrosion varnish etc It the problem cannot be corrected the actuator must be replaced 4 If the engine rpm noted in 3c is not within the specified TRC speed range adjust throttle lever actuator THROTTLE LEVER ACTUATOR Fig 10 Throttle Lever Actuator EMISSION CONTROL SYSTEMS 6 9 Replacement Disconnect vacuum hose at actuator Remove two screws and actuator Reverse procedure to install and refer to throttle lever actuator for adjustment Adjustment Fig 11 l PLUNGER SCREW Disconnect valve to actuator hose at valve and connect to an external vacuum source equipped with a vacuum gauge Check throttle lever shaft and linkage to be sure that they operate freely without binding or sticking Start engine and run until warmed up and idle is stable Place transmission in neutral or park
55. Over Center Adjusting Serew Locknut 35 Ibs ft 14 lbs in Max In excess of ball drag excess of ball drag and thrust bearing preload Total Steering Gear Preload POWER STEERING PUMP PRESSURES G30 P10 30 1200 1300 psi 900 1000 psi 1200 1300 psi Motor Home amp K 1200 1300 psi 1350 1450 psi TRUCK SUPP SPECS SPECIFICATIONS 23 Steering Wheel Nut Turn Signal Lever Screw Tilt Wheel Lever Ignition Switch Screw Turn Signal Switch Screws Turn Signal Housing Screws Lock Bolt Spring Screw Tilt Bearing Housing Support Screws Tilt Steering Column Bracket Screws Column Support to Column Bracket Stud Nuts Column Support to Column Bolts Column to Dash Panel Clamp Screws Firewall Toe Panel Bracket Clamp Bolt Floor Pan Cover Screws Floor Pan Cover Clamp Screws Toe Panel Cover Screws Lower Coupling to Wormshaft Clamp Bolt Upper and Lower Univesal Joint Clamp Lower Bearing Adjusting Ring Bolt Upper Steering Shaft Clamp Lower Mast Jacket Bearing Clamp Bolt Flexible Coupling Stud Nuts Steering Gear Mounting Bolt Nuts TORQUE SPECIFICATIONS Component C10 30 G10 30 K10 20 P10 30 MotorHome 30 ft Ibs 30 ft 155 30 ft Ibs 20 in Ibs 20 in 165 20 in 165 20 in Ibs 35 in Ibs 3
56. SEQUENCE RESULT REMOVE CAP ASSY r _ I e i STARTS VISUALLY INSPECT REPAIR AS Le e FOR MOISTURE DUST NECESSARY DISCONNECT CRACKS BURNS ETC 3 WIRE CONNECTOR OFF READS ABOVE 1 OHM X1 SCALE REPLACE COIL CONNECT OHMMETER READS 0 TO 1 OHM X1 SCALE 2 EITHER TEST READS 6 000 2 TO 30 000 OHMS r STARTS CONNECT OHMMETER BOTH TESTS REPLACE READ INFINITY DIE Q REMOVE GREEN amp WHITE LEADS FROM MODULE LESS THAN INFINITY REPLACE COIL PICK UP X 1000 SCALE CONNECT OHMMETER FROM GROUND TO EITHER READS INFINITE LEAD X 1000 SCALE CONNECT OHMMETER REPEAT STEPS 8 AND 9 ACROSS 2 LEADS WHILE MOVING VAC ae ADVANCE WITH SCREW 7 DRIVER IF READING ISSTILL OK DOES NOT READ 500 TO 1500 0HMs REPLACE COIL PICK UP READS 500 TO 1500 OHMS GE _ steps 5 THRU 9 Od IFOK i CHECK MODULE 69 A WITH TESTER IF NOT OK ERE ADS REPLACE MODULE TRUCK SUPP SERVICE 6Y 22 ENGINE ELECTRICAL HIGH ENERGY IGNITION SYSTEM VB engine PROBLEM engine RUNS ROUGH or CUTS OUT SEQUENCE RESULT MUT TS I 1 gt 4 RUNS SMOOTH CHECK SPARK PLUGS amp PLUG WIRES REPAIR OR A w m 2 REPLACE REMOVE IN n CAP ASSY
57. The Servo Unit is mounted on the left front inner fender and is connected by a cable to the throttle linkage It opens or closes the throttle as dictated by the Regulator THE CRUISE CONTROL ENGAGE SWITCH ASSEMBLIES BOTH TURN SIGNAL amp INSTRUMENT PANEL MOUNTED TYPES INCORPORATE THREE POSITION SWITCHES THESE POSITIONS ARE A THE RELEASED OR NORMAL POSITION B THE ENGAGE POSITION C THE TRIM DOWN POSITION PARTIALLY DEPRESSING THE ENGAGE SWITCH WILL ACTIVATE THE SYSTEM AND IT WILL REMAIN ACTIVITED WHEN THE SWITCH 15 RELEASED THE CRUISE SYSTEM 15 DEACTIVATED WHEN THE BRAKES ARE APPLIED OR WHEN THE ENGAGE SWITCH IS DEPRESSED FULLY AND HELD IN THE TRIM DOWN POSITION THE TRIM DOWN SWITCH POSITION 15 NORMALLY USED TO DECREASE THE CRUISING SPEED WHILE THE SWITCH IS HELD IN THE TRIM DOWN POSITION THE CRUISE SYSTEM IS OFF AND THE CAR SPEED WILL GRADUALLY DECREASE WHEN THE DESIRED CRUISING SPEED IS REACHED THE SWITCH IS SLOWLY RELEASED AND THE CRUISE SYSTEM WILL RE ENGAGE IF THE SWITCH 15 RELEASED FROM THE TRIM DOWN POSITION VERY RAPIDLY IT IS QUITE LIKELY THAT THE SYSTEM WILL NOT RE ENGAGE THIS IS NORMAL AND IS AVOIDED BY A SLOWER MORE DELIBERATE RELEASE OF THE SWITCH FROM THE TRIM DOWN POSITION NOTE A SPEED SWITCH BUILT INTO THE REGULATOR ASSEMBLY PREVENTS ENGAGING THE CRUISE SYSTEM BELOW APPROX 30 MPH Fig 1C Cruise Master Engagement Switches TRUCK SUPP SERVICE HOLD E
58. There are two types of High Energy Ignition HEI distributors The 8 cylinder distributor fig 11 combines all ignition components in one unit The ignition coil is in the distributor cap and connects directly to the rotor The 6 cylinder distributor fig 2i has an external mounted coil Both operate basically in the same manner as a conventional ignition system except the module and pick up coil of the HEI system replace the contact points of the conventional System GROUND TERMINAL B TERMINAL BAT TERMINAL CONNECTED TO IGNITION SWITCH LATCH 4 2 CONNECTOR CONNECT TACHOMETER FROM THIS TERMINAL D C TERMINAL GROUND TACH TERMINAL SOME TACHOMETERS MUST CONNECT FROM THIS TERMINAL TO ENERGIZER POSITIVE CONSULT TACHOMETER MANUFACTURER Fig 1i 8 Cylinder HEI Distributor The High Energy Igntion is a pulse triggered transistor controlled inductive discharge ignition system magnetic pick up assembly located inside the distributor contains a permanent magnet a pole piece with internal teeth and a pick up coil When the teeth of the timer core rotating inside the pole piece line up with teeth of the pole piece an induced voltage in the pick up coil signals the all electronic module to open the coil primary circuit The primary current decreases and a high voltage is induced in the ignition coil secondary winding which is directed through the rotor and high voltage leads to fire the s
59. battery acid or electrical burns and or 2 damage to electronic components of either vehicle Never expose battery to open flame or electric spark batteries generate a gas which is flammable and explosive Do not allow battery fluid to contact eyes skin fabrics or painted surfaces fluid is a corrosive acid Flush any contacted area with water immediately and thoroughly Be careful that metal tools or jumper cables do not contact the positive battery terminal or metal in contact with it and any other metal on the vehicle because a short circuit could occur Batteries should always be kept out of the reach of children Jump Start Procedure 1 Wear eye protection and remove rings metal watch bands and other metal jewelry 2 Set parking brake firmly Place automatic transmission in PARK in both vehicles don t let vehicles touch and turn ignition key to LOCK in vehicle with discharged battery Neutral and OFF in vehicles with manual transmission Also turn off lights heater and all unnecessary electrical loads 3 Attach one end of a jumper cable to one battery s positive terminal identified by a red color or P on the battery case post or clamp and the other end of the same cable to the positive terminal of the other battery 4 Attach the remaining jumper cable FIRST to the negative terminal black color N of the OTHER vehicle s battery regardless of which vehicle has the dischar
60. clutch is fully depressed TRANSMISSION SHIFT INDICATOR Check to be sure automatic transmission shift indicator accurately indicates the shift position selected STEERING Be alert to any changes in steering action The need for inspection or servicing may be indicated by increased effort to turn the steering wheel excessive free play or unusual sounds when turning or parking 5 WHEEL ALIGNMENT AND BALANCE addition to uneven or abnormal tire wear the need for wheel alignment service may be indicated by a pull to the right or left when driving on a straight and level road The need for wheel balancing is usually indicated by a vibration of the steering wheel or seat while driving at normal highway speeds BRAKES Be alert to illumination of the brake warning light or changes in braking action such as repeated pulling to one side unusual sounds either when braking or between brake applications or increased brake pedal travel Any of these could indicate the need for brake system inspection and or service EXHAUST SYSTEM Be alert to any change in the sound of the exhaust system or a smell of fumes which may indicate a leak requiring inspection and or service See also Engine Exhaust Gas Caution in Item B 3 of this section WINDSHIELD WIPER AND WASHER Check operation of wipers as well as condition and alignment of wiper blades Check amount and direction of fluid sprayed by washers during use
61. miles or 6 months with water resistant EP chassis lubricant which meets General Motors Specification GM 6031 M UNIVERSAL JOINTS universal joints are the needle bearing type Lubricate those universal joints depending on truck model equipped with lube fittings every 7 500 miles or 6 months with water resistant EP chassis lubricant which meets General Motors Specification GM 6031 M More frequent lubes may be required on heavy duty or Off the Road operations WHEEL BEARINGS Front NOTE Use wheel bearing lubricant GM Part No 1051344 or equivalent This is a premium high melting point lubricant which meets all requirements of General Motors Specification GM 6031 M Due to the weight of the tire and wheel assembly it is recommended that they be removed from hub before lubricating bearings to prevent damage to oil seal Then remove the front wheel hub to lubricate the bearings The bearings should be thoroughly cleaned before repacking with lubricant Front wheels are equipped with tapered roller bearings on all trucks Wheel bearings should be lubricated every 30 000 miles 12 000 miles in four wheel drive trucks Do not mix wheel bearing lubricants CAUTION Long fibre type greases should not be used on roller bearing front wheels Rear The rear wheel bearings receive their lubrication from the rear axle When installing bearings which have been cleaned prelube with wheel bearing grease TRUCK SUPP SERVICE
62. modification to the lock assembly due to the new radiator grille as shown in Fig 1 CARBURETOR OUTSIDE AIR INLET SNORKELS Fig 2 Removal Raise hood and remove carburetor air duct from air snorkel by sliding duct rearward 2 Remove two 2 screws attaching air snorkel to radiator support and remove from vehicle Installation Reverse removal procedure to install snorkel Fig 1 Hood Lock Catch and Support CK Series REAR FENDER CK SERIES Refer to Figs 3 and 4 for removal and installation of rear HOOD ROD SUPPORT G SERIES fenders and fender braces for both C and K Series Trucks Refer to Fig 6 for removal and installation of hood rod RUNNING BOARDS CK SERIES support Refer to Fig 5 for removal and installation of running boards and hangers TRUCK SUPP SERVICE 11 2 CHASSIS SHEET METAL tw A CK 109 209 309 KE Fig 2 Carburetor Outside Air Inlet Snorkels CK Series Fig 5 Running Board Hanger and Brace CK Series SIDE PANEL ASSEMBLY BRACE ASSEMBLY Fig 3 Rear Fender and Brace CK Series SIDE PANEL ASSEMBLY REAR FENDER ASSEMBLY Fig 4 Dual Wheel Fender C Series Fig 6 Hood Rod Support G Series TRUCK SUPP SERVICE SECTION 12 ELECTRICAL BODY AND CHASSIS NOTE Except for the following changes all information listed in Section 12 of the 1974 Light Duty Truck Service Manual is applicable to 1976 light duty trucks Refer to 1974 Light Duty Truck Service Manual for any se
63. ring seal and modulator valve from case fig 1A Discard O ring INSPECTION OF CONVERTER 1 Check converter for leaks as follows fig 3A a Install Tool J 21369 and tighten b Apply 80 psi air pressure to tool c Submerge in water and check for leaks 2 Check converter hub surfaces for signs of scoring or wear CONVERTER END CLEARANCE CHECK Figs 4A and 5A 1 Fully release collet end of Tool J 21371 8 2 Install collet end of Tool J 21371 8 into converter hub until it bottoms then tighten cap nut to Sft lbs fig 4A O RING SEAL VACUUM VACUUM MODULATOR Fig 1A Removing Vacuum modulator Assembiy 3 Install Tool J 21371 3 and tighten hex nut to 3 ft 16 iv fig 5A 4 Install Dial Indicator J 8001 and set it at zero while its plunger rests on the cap nut of Tool J 21371 8 5 Loosen hex nut while holding cap nut stationary With the hex nut loosened and holding Tool J 21371 3 firmly against the converter hub the reading obtained on the dial indicator will be the converter end clearance End clearance should be less than 050 If the end clearance is 050 or greater the converter must be replaced TRUCK SUPP OVERHAUL 74 2 AUTOMATIC TRANSMISSION CLUTCH ASSEMBLIES FOR THM 350 d e CLUTCH DRIVEN CUSHION PLATE PLATES SPRING TAXI AND TRUCK EN ERES 305380 8 400 8 TAXI AND TRUCK DIRECT 250 1 6 262 8 3 3 NONE 305 350 V 8 400 V 8 TAXI
64. sides and allow the vapor pressure to release from the compressor Disconnect both Gage Adapters J 5420 from the Test Plate J 9625 Rotate the complete compressor assembly not the crankshaft or drive plate hub slowly several turns to distribute oil to all cylinder and piston areas Install a shaft nut on the compressor crankshaft if the drive plate and clutch assembly are not installed Using a box end wrench or socket and handle rotate the compressor crankshaft or clutch drive plate on the crankshaft several turns to ensure piston assembly to cylinder wall lubrication Connect the Charging Station HIGH pressure line or a HIGH pressure gage and Gage Adapter J 5420 to the Test Plate J 9625 HIGH side connector Attach a Adapter J 5420 to the suction or LOW pressure port of the Test Plate J 9625 to open the schrader type valve NOTE Oil will drain out of the compressor suction port adapter if the compressor is positioned with the suction port down Attach the compressor to the Holding Fixture J 25008 1 R 4 compressor and J 9396 6 compressor and clamp the fixture in a vise so that the compressor can be manually turned with a wrench TRUCK SUPP OVERHAUL 1 26 AIR CONDITIONING COMPRESSOR 15 Using a wrench rotate the compressor crankshaft or drive plate hub 10 complete revolutions at a speed of approximately one revolution per second NOTE Turning the compressor at less than one revolution per second can
65. slotted off idle port As the throttle valve is opened it passes the off idle port gradually exposing it to high vacuum below the throttle valve The additional fuel from the off idle port mixes with the increased air flow past the opening throttle valve to meet increased engine air and fuel demands Further opening of the throttle valve causes increased air flow through the carburetor bore which causes sufficient pressure drop in the multiple venturi to start fuel delivery from the main discharge nozzle The off idle port fuel discharge does not cease at this transfer point but rather diminishes as fuel flow from the main discharge nozzle increases In this way the systems are so designed that they combine to produce a smooth fuel flow at all engine speeds The lower idle air bleed is used strictly as air bleed during idle operation It supplies additional air to the idle circuit for improved atomization and fuel control at low engine speeds The same air bleed is used as an additional fuel feed at higher engine speeds to supplement main discharge nozzle delivery during operation of the main metering system TRUCK SUPP SERVICE 6M 4 ENGINE FUEL The timed spark port has one tube which supplies vacuum during the off idle and part throttle operation of the carburetor The tube leads to the purge valve on the vapor canister to provide a means of pulling fuel vapors from the canister during periods of higher air flow through the
66. 0 10 GENERAL INFORMATION AND LUBRICATION BRAKE MASTER CYLINDER Check master cylinder fluid level in both reservoirs every 7 500 miles or 6 months If the fluid is low in the reservoir it should be filled to a point about 1 4 from the top rear of each reservoir with Delco Supreme No 11 Hydraulic Brake Fluid or equivalent BRAKE AND CLUTCH PEDAL SPRINGS Lubricate brake and clutch pedal springs every 7 500 miles or 6 months with engine oil for all models PARKING BRAKE Every 7 500 miles or 6 months clean and lubricate all parking brake pivot points with water resistant EP chassis lubricant which meets General Motors Specification GM 6031 M STEERING Manual Steering Gear The steering gear is factory filled with steering gear lubricant Seasonal change of this lubricant should not be performed and the housing should not be drained no lubrication is required for the life of the steering gear Every 30 000 miles the gear should be inspected for seal leakage actual solid grease not just oily film If a seal is replaced or the gear is overhauled the gear housing should be refilled with No 1051052 13 oz container Steering Gear Lubricant which meets GM Specification GM4673 M or its equivalent NOTE Do not use EP Chassis Lube which meets GM Specification GM 6031 M to lubricate the gear DO NOT OVER FILL the gear housing Power Steering System Check the fluid level in the pump reservoir at each oil change period Add G
67. 18 not required however if the car is raised for other service it is advisable to check the general condition of the catalytic converter pipes and mufflers CAUTION When jacking or lifting vehicle from frame side rails be certain lift pads do not contact catalytic converter as damage to converter will result COMPONENT PART REPLACEMENT GENERAL Exhaust System Pipes and Resonators Rearward of the Mufflers Must Replaced Whenever A New Muffler Is Installed NOTE When a muffler is replaced use sealing compound at the clamped joint to prevent leaks Truck exhaust systems vary according to series and model designation Series 10 30 trucks use a split joint design system in which the exhaust pipe to muffler are clamped together and muffler to tailpipe connections are welded together All mufflers and tailpipes are welded assemblies no clamps in 1976 NOTE 10 20 30 series exhaust systems aluminized steel except 1 C Series exhaust pipes and 2 stainless steel exhaust pipes on vehicles equipped with underfloor catalytic converters Always use correct replacement parts when servicing these systems When installing a new exhaust pipe or muffler and tailpipe on any model care should be taken to have the correct alignment and relationship of the components to each other Particular care should be given to the installation of the exhaust pipe and crossover pipe assembly on V 8 engine single exhaust systems I
68. 2 and Driver J 7079 2 as shown in Fig 5 Discard the seals Wash all parts in clean solvent and dry parts with compressed air Inspect thrust bearing spacer for wear or cracks Replace if damaged 6 Inspect thrust bearing rollers and thrust races for wear pitting or scoring If any of these conditions exist replace the bearing thrust races spacer and retainer Assembly If the needle bearing was removed place new needle bearing over Tool J 8524 1 and J 7079 2 with the bearing manufacturer s identification against the tool and drive the bearing into the adjuster plug until the tool bottoms in the housing Fig 6 CAUTION P ace a block of wood under the adjuster plug to protect during driving of the bearing Place dust seal and a new stub shaft seal on Tool J 8524 1 face of seal with part number against tool Lubricate seal with Power Steering Fluid and drive or press seal into adjuster plug until seated Fig 7 When properly installed the stub shaft seal under the dust seal and the inner dust seal lip is not bottomed on the stub shaft assembly Install retaining ring with Internal Pliers J 4245 Lubricate the thrust bearing assembly with Power Steering Fluid Place the flanged thrust bearing race on the adjuster plug hub then install the thrust bearing small bearing race flanged side up and spacer grooves of spacer away from bearing race Install bearing retainer on the adjuster
69. 50W low beam 1976 TRUCK SUPP SPECS SPECIFICATIONS 28 RADIATOR AND GRILLE SECTION 13 TORQUE SPECIFICATIONS CK Grille to Tie Bar 96 in lbs Grille joins gos 96 in Ibs bolts 50 in lbs screws Grille Bracket to Radiator Support 150 in 105 gis 120 in bs P 32 Fan Shroud ds in Ibs 42 in 165 286 in Ts Bus Fan Guard 96 in lbs Coolant Recovery Tank Brkt 30 in Ibs 23 in lbs E Drain Plug 112 in lbs 112 in lbs Hose Clamps _17 in lbs 17 in lbs a Radiator Mounting Panel Radiator Mounting Bracket To Radiator and Brace Motor Home E Frame Radiator Support Bracket To Frame Radiator Baffle Radiator Baffle Seal Retainer 150 in lbs 18 ft lbs upper ft lbs lower Radiator Mounting Strap Filler Neck Support Support Bracket to Radiator su SECTION 14 TORQUE SPECIFICATIONS C P AND K TORQUE SPECIFICATIONS G Front BUMP er c Re Nw OS S 35 ft Ibs Front Face Bar to Bracket ve tores 24 ft lbs Front Bumper Bracket and Brace 70 ft lbs Bracket to Cross Sil 24 ft 5 Rear Bumper to Outer Bracket 35 ft lbs License Plate Bracket to Face 100 in Ibs Rear Bumper Outer Bracket and Brace 50 ft lbs Rear Face Bar to Brackets 55 ft Ibs License Plate Bracket
70. 53 BEARING 2 54 ABRASION SHIELD 55 BOLT 56 NUT TRUCK SUPP SERVICE STEERING 9 3 SERVICE OPERATIONS CK SERIES P MOTOR HOME G CUSTOM Fig 2 Steering Wheel Snap Ring STEERING WHEEL Fig 2 Removal The service procedures for the removal and installation of the steering wheel are identical to the procedures outlined in the 1974 Light Duty Truck Service Manual Section 9 with the exception of the addition of a steering wheel snap ring as shown in Figure 2 Refer to Page 9 29 of the 1974 Light Duty Truck Service Manual for proper removal procedure When removing the steering wheel remove the snap ring as Step 3 in the removal procedure Installation When installing the steering wheel replace the snap ring after tightening the steering wheel nut to proper torque specifications DIRECTIONAL SIGNAL SWITCH Standard Column The service procedure for the removal and installation of the directional signal switch is identical to the 1974 vehicle with the exception of the lock plate cover as shown in Figure 3 Removal procedure step number 3 for standard steering columns should read 3 Position screwdriver blade into cover slot fig 3 Pry up and out to free cover from lock plate Installation Procedure step 7 for standard column should read Fig 3 Removing Lock Plate Cover 7 Place cover on the lockplate and snap into position STEERING LINKAGE All service procedure for the
71. 6 Turn fast idle screw to obtain specified rpm SEND TANG AWAY TO 7 Remove plug and connect vacuum hose at EGR Fig 44 Pump Rod Adjustment 8 On 454 engine remove plug and connect vacuum hose to front vacuum break unit 9 Remove tachometer and stop engine 3 Gauge from top of choke valve wall next to vent stack CHOKE COIL LEVER ADJUSTMENT Fig 46 to top of pump stem 1 Loosen three retaining screws and remove the thermostatic cover and coil assembly from choke housing 2 Place pump rod in specified hole in lever 4 To adjust support pump lever with screwdriver and bend pump lever 2 Push up on thermostatic coil tang counterclockwise 5 Adjust idle speed until choke valve is closed FAST IDLE ADJUSTMENT Fig 45 3 Insert specified plug gauge in hole in choke housing On Bench 4 Lower edge of choke coil lever should just contact side 1 Place cam follower on high step of the fast idle cam and of plug gauge hold the follower against the cam 5 Bend choke rod at point shown to adjust see inset 2 While holding the follower against the high step of the 6 Install thermostatic cover and coil referring to fast idle back fast idle screw automatic choke coil adjustment counterclockwise until it pulls away from the fast idle FAST IDLE CAM CHOKE ROD ADJUSTMENT cam follower Turn in fast idle screw clockwise until Fig 47 the screw just contacts the fast idle cam follower NOTE Choke
72. 6M 33 Rear Vacuum Break 6M 42 Exhaust Gas Recirculation eese 6M 33 Automatic Choke Coil Adjustment 6 43 Canister tertio 6M 34 Unloader Adjustment eee 6M 44 Main System enne ennt tnn 6M 34 Secondary Throttle Valve Lock Out Adjustment 6M 44 Power System ones nene teen 6M 34 Secondary Closing 6 45 Air Valve 6 36 Secondary Opening Adjustment 6M 45 Accelerating Pump System sss 6M 37 Air Valve Spring Wind Up Adjustment 6M 45 Choke SySten iuri nter fite erp 6M 37 Throttle Lever Actuator Adjustment 6M 45 Maintenance and Adjustment sse 6M 40 Service 5 aya 6 46 Idle Speed Adjustment sese 6M 40 Carburetor Replacement sese 6M 46 6 40 Fuel Filter Replacement eee 6M 46 Idle Mixture Adjustment esee 6M 40 Air Horn Tightening Sequence 6M 46 Pump Rod Adjustment esses 6M 41 Diagriosis 2 Dia x aa RR 6M 47 Fast Idle Adjustment eene 6M 41 Choke Coil Lever Adjustment
73. 9 11 454 4 RESERVOIR ASSEMBLY MOTOR HOME Fig 30 Reservoir Assembly TRUCK SUPP SERVICE 9 12 STEERING 1 PUMP PULLEY REMOVER J 25034 2 PUMP PULLEY INSTALLER J 25033 Fig 31 Special Tools TRUCK SUPP SERVICE SECTION 10 WHEELS AND TIRES The 1976 wheel and tire maintenance and service operations remain essentially the same as outlined in the 1974 Truck Service Manual Tire Inflation Pressure Tables and additional information for torquing dual wheels on P300 models have ATTACHMENT OF DUAL WHEELS ON P300 MODELS assure secure attachment of the dual disc wheels it is been revised as listed below to 1976 specifications important that all dirt or rust scale be removed from the mating surface of the wheels hub and clamp ring as well as the stud and nut POWER DRIVE NUTS THEN MANUALLY INSPECT TORQUE AT 130 180 FT LBS MANUAL TORQUE ONLY 150 200 FT LB DUAL WHEEL TYPICAL WHEEL MAXIMUM MAXIMUM LOAD PRESSURE STAMP RIM SIZE DIA X WIDTH WHEEL CODE LETTERS OPTIONAL LOCATIONS FOR MAXIMUM PRESSURE MAXIMUM LOAD STAMPS SINGLE WHEEL TYPICAL WHEEL AXIMUM PRESSURE MAXIMUM LOAD STAMP OPTIONAL LOCATIONS MAXIMUM FOR MAXIMUM toap PRESSURE STAMP WHEEL CODE LETTERS RIM SIZE DIA X WIDTH Fig 1 Wheel Code Location TRUCK SUPP SERVICE O r f LEELA LLL LLL 10 2 WHEELS AND TIRES TIRE LOAD amp INFLATION PRESSURE PASSENG
74. AND TRUCK REVERSE 4 250 L 6 262 305 V 8 350 V 8 400 V 8 TAXI AND TRUCK Fig 3A Air Checking Converter J 21371 8 Fig 4A Loosening Collet on Tool J 21571 8 Fig Converter End Clearance TRUCK SUPP OVERHAUL AUTOMATIC TRANSMISSION 7A 3 TURBO HYDRA MATIC 375 400 475 TRANSMISSION INDEX Rear Servo Valve Body Spacer Gasket Front Sery Onestea eng 7 3 Oil Pump and Internal Case 5 7 4 Speedometer Drive Gear 7 4 Control Vial Ve os 7A 5 Forward Clutch eee 7 7 7 9 Center SUPPO D Dosen 7A 10 Reaction Carrier Roller Clutch and Output Carrier Assembly T oem 7A 10 Front and Rear Bands Support to Case Spacer 7A 10 Case Extension Except CL Model 7A 10 Case Extension CL Model 7A 11 1 see en ee 7 11 Rear E 7A 11 Units to Transmission Case sees 7A 11 Extension eese eee eta eee 7A 11 Check Balls Control Valve Spacer Plate and Gasket Detent Solenoid Front Servo Assembly and Electrical Connector TA 12 Modulator Valve and Vacuum Modiulator 7A 12 ConvertercAssenibly 4 3 entities 7A 12 REAR SERVO VALVE BODY SPACER GASKET AND FRO
75. Apply 20 in Hg vacuum to actuator Manually open throttle slightly and allow to close against the extended actuator plunger Note the engine rpm If rpm noted above is not within specified speed range then turn plunger screw on actuator plunger in the appropriate direction and repeat step No 4 until specified TRC speed range is obtained The TRC speed range for a 350 400 V8 is 1500 rpm and for a 454 V8 is 1400 rpm ADJUST IDLE SPEED SCREW TO OBTAIN SPECIFIED R P M TO 20 IN HG VACUUM SOURCE THROTTLE LEVER THROTTLE LEVER ACTUATOR Fig 1 1 Throttle Lever Actuator Adjustment TRUCK SUPP SERVICE SECTION 6Y ENGINE ELECTRICAL NOTE Except for the following changes all information listed in Section 6Y of the 1974 Truck Service Manual is applicable to 1976 light duty trucks Refer to 1974 Truck Service Manual for any service procedure not contained herein Illustrations showing complete engine wiring for each truck line are shown in figures 1 through 11 GENERATOR NOTE PRESS BOOT OVER TERMINAL WITH SMALL END DOWN TO FUEL METER BATTERY CABLE LEFT SIDE RIGHT SIDE STARTING MOTOR Fig 1 C 10 03 Truck L 6 LD4 w o F44 Engine Wiring TRUCK SUPP SERVICE 6Y 2 ENGINE ELECTRICAL CARB SOL BATTERY CABLE CYLINDER AS 7 II TO FUEL METER STARTING MOTOR gt W views NOTE PRESS BOOT OVER TERMINAL WITH SMALL EN
76. Assembly NOTE Keys have small lip on each end When correctly installed this lip will fit over spring fig 14R Extension Oil Seal or Bushing If bushing in rear of extension requires replacement remove seal and use Tool J 5778 to drive bushing into extension housing fig 15R Using the same tool drive new bushing in from the rear Coat LD of bushing and seal with transmission lubricant then install new seal using Tool TRUCK SUPP OVERHAUL 7M 6 MANUAL TRANSMISSION O RING LOCATION Fig 11R Shift Fork Shafts ALIGN ROLL PIN WITH COUNTERBORE WHEN INSTALLING COUNTERBORE REVERSE IDLER GEAR SHAFT Fig 12R Removing Reverse Idler Gear Shaft J 5154 fig 16R Clutch Bearing Retainer Oil Seal If the lip seal in the retainer needs replacement pry the old seal out and replace with a new seal using Installer Tool J 25233 or similar tool until seal seats in its bore fig 17R ASSEMBLY OF MAINSHAFT 1 Install First Reverse synchronizer hub on output shaft splines by hand Slotted end of hub should face front of shaft Use an arbor press to complete hub installation on shaft and install retaining snap ring in most rearward groove CAUTION DO NOT attempt to drive hub onto shaft with hammer Hammer blows will damage hub and splines SPRING UNDER LIP OF FIRST REVERSE SLEEVE AND GEAR RETAINING SNAP RING FIRST REVERSE SYNCHRONIZER Fig 13R First Reverse Synchronize
77. C MAX NORM or BI LEVEL or DEF positions electrical circuit connection is made to the compressor clutch through the control panel switch and the compressor discharge pressure switch If the compressor discharge pressure switch is closed ambient temperature above approximately 42 F the compressor will run In the OFF or ECONOMY VENT or HEATER positions the compressor clutch is not energized The system selector lever also determines the direction of outlet air flow Moving the lever from mode to mode varies the position of a vacuum valve on the control The position of the vacuum valve will supply vacuum to or vent vacuum diaphragms which position the upper and lower mode and defroster air doors in the selector duct assembly The position of these air doors determines if output air flow is from the heater purge outlet at OFF the heater outlet with slight air flow from defroster nozzles at HEATER heater and A C outlets at VENT A C outlets only at MAX and NORM heater A C and defroster outlets at BI LEVEL or the defroster outlets with slight airflow from the heater outlet at DEF TRUCK SUPP SERVICE 1 4 HEATER AND AIR CONDITIONING Locking Washer Pulley Rim O Ring Coil and Housing Assy O Ring Rotor Bearing Screw Rotor and Bearing Assy Retaining Ring Clutch Drive Assy Clutch Hub Key Shaft Nut O Ring 1 2 3 4 5 6 7 8 Retaining Ring Screw Superheat Switch Pressure Rel
78. Check all vacuum hoses leading into the manifold or carburetor base for leaks or being disconnected Install or replace as necessary Torque carburetor to manifold bolts 10 14 ft lbs Using a pressure oil can spray light oil or kerosene around manifold legs and carburetor If engine RPM changes tighten or replace the manifold gaskets or carburetor base gaskets as necessary Normally the hot idle compensator should be closed when engine is running cold and open when engine is hot approx 140 F at comp replace if defective 1 Remove air horn and check float adjustment as specified in carburetor overhaul section 2 Check float needle and seat for proper seal If a needle and seat tester is not available mouth suction can be applied to the needle seat with needle installed If the needle is defective replace with a factory matched set 3 Check float for being loaded with fuel bent float hanger or binds in the float arm NOTE A solid float can be checked for fuel absorption by lightly squeezing between fingers If wetness appears surface or float feels heavy check with known good float replace the float assembly 4 If excessive dirt is found in the carburetor clean the fuel system and carburetor Replace fuel filter as necessary TRUCK SUPP SERVICE 6M 14 ENGINE FUEL Problem sm AU ra ENGINE CRANKS TURNS OVER BUT WILL NOT START OR STARTS HARD WHEN COLD POSSIBLE CAUSE
79. Control System ECS Vehicles Controls emission of gasoline vapor to the atmosphere by means of an integral separator with the fuel tank that separates vapor from liquid fuel a filler cap that doesn t permit venting into the atmosphere a canister for storage of vapors lines hoses and valves to control and transport vapors from fuel tank to storage and finally to the carburetor for utilization in running the engine Refer to Section 8 in the 1974 Light Duty Truck Service Manual for service procedures Carburetor Hot Air Vehicles Meters and mixes heated air with incoming cold air to optimize fuel vaporization Refer to Section 6M for service procedures of air cleaner and air intake duct Controlled Combustion System CCS Federal Increases combustion efficiency through leaner carburetor mixtures and revised distributor calibration Thermostatically controlled damper in the air cleaner silencer maintains warm air intake to carburetor Refer to Section 6M for air cleaner service procedures Underfloor Converter Vehicles except 454 V8 The flow of exhaust gases down through the catalyst within the converter effectively controls the hydrocarbon and carbon monoxide to a more desirable emission Refer to Section 8 for service procedures Air Injection Reactor A I R C10 and G10 350 V8 Cal Compresses regulates and distributes quantities of air to the exhaust to more completely burn carbon monixide and
80. Cylinder Radial oee 10 0 Cu In Rotation esed PUR Clockwise Amps RPM Volts Cold Cold CNRC Fuse Block Blower Motor Ger c rcm 25 Amp C K Four Season 12 0 12 8 Max 3400 Min Motor Home Chassis Unit 20 Amp C K G Overhead G Floor and In Line Motor Home C K Four Season Systems 30 Amp Units hne 12 0 13 7 Max 3400 Min C K Overhead System Motor Home Chassis None Compressor Clutch Coil Ohms at SUMUS CT SL 3 70 Circuit Breaker Amps S 3 33 12 volts Model 85 Amp TRUCK SUPP SPECS SPECIFICATIONS 2 FRONT END Windshield Wiper Linkage to Plenum 25 in Sunshade Support 20 in Inside Rear View Mirror to 45 in Outside Rear View Mirror to Door Panel Base MIIOE RC edP n 25 in West Coast Mirror Lower Bracket to Door 20 in Upper Bracket to Door 45 in DOORS Window Regulator Assembly to Door Panel 85 in Remote Control Door Lock to Door 45 in Lock Striker to Body Pillar 45 ft Outside Door 85 in Inside Door Handle 85 in Hinges to Body and Door 35 ft Front Door Window Run Channel to Door 85 Front Door Ventilator Assembly Vent Screw 2 2
81. Fig 4C Electric The Cruise Master brake release switch electrical contacts must be switched open when the brake pedal is depressed 38 to 64 measured at the brake pedal An inoperative switch must be replaced Switch replacement procedure is similar to standard brake lamp switch CRUISE CONTROL VACUUM HOSE CABLE replacement Vacuum The vacuum valve plunger must clear the pedal arm when the arm is moved 5 16 inch measured at the switch fig 6C An inoperative sticking plugged or leaking vacuum valve must be replaced Vacuum valve replacement is similar to brake lamp switch replacement Be certain that the hose to the valve is connected firmly and is not cracked or deteriorated COLUMN MOUNTED ENGAGEMENT SWITCH The engagement switch is serviced only by replacement of the turn signal lever assembly SERVO BOOT SS SERVO ACCELERATOR CABLE SUPPORT LF4 LF8 LS9 CONTROL CABLE ADJUSTMENT With Cable installed to Cable Bracket and Carburetor install Cable to Servo Bracket Using second ball on Servo Chain install Servo Chain on Cable With throttle completely closed ignition off and fast idle Cam off adjust Cable Jam Nuts until Servo Chain is almost tight some slack Tighten Jam Nuts to specified torque then remove plostic retainer not shown used to retain boot in depressed position and pull rubber boot part of Servo over washer port of Cable Snap Fastene
82. Front Output Bearing Retainer Bolts Output Shaft Yoke Nuts Front Output Rear Bearing Retainer Bolts 30 ft Differential Assembly Screws Rear Output Shaft Housing Poppet Ball Retainer Nut Power Take Off Cover Bolts Front Input Bearing Retainer Bolts Filler Plug TURBO HYDRA MATIC 350 Pump Cover to Pump Body 17 ft 18 1 2 ft in lbs lbs in 5 lbs lbs in Ibs lbs lbs Ibs 5 5 Pump Assembly to Case Valve Body and Support Plate Parking Lock Bracket Oil Suction Screen Oil Pan to Case Extension to Case Modulator Retainer to Case Inner Selector Lever to Shaft Detent Valve Actuating Bracket Converter to Flywheel Bolts Under Pan to Transmission Case Transmission Case to Engine Oil Cooler Pipe Connectors to Transmission Case straight pipe fitting tapered pipe fitting Oil Cooler Pipe to Connectors Detent Cable to Transmission Detent Cable to Carb Pump Cover Boits Parking Pawl Bracket Bolts Center Support Bolt Pump to Case Attaching Bolts Extension Housing to Case Attaching Bolts 23 ft Rear Servo Cover Bolts Detent Solenoid Bolts Control Valve Body Bolts Modulator Retainer Bolt Governor Cover Bolts Manual Lever to Manual Shaft Nut Manual Shaft to Inside Detent Lever Linkage Swivel Clamp Nut Converter Dust Shield Screws Transmission to Engine Mounting Bolts Converter to Flywheel Bolts Rear Mount to Transmission Bo
83. Fuel Pump 350 400 V8 ENGINE FUEL 6 73 speeds between 450 1 000 rpm If pressure is too low too high or varies significantly at different speeds the pump should be replaced REMOVAL NOTE Whenever disconnecting or connecting fuel pump outlet pipe fitting always double wrench to avoid damaging fuel pump 1 Disconnect fuel inlet and outlet pipes at fuel pump 2 Remove fuel pump mounting bolts and remove pump and gasket 3 On V8 engines if push rod is to be removed remove pipe plug and push rod 454 cu in engines and fuel pump adapter and gasket and push rod 350 and 400 cu in engines INSTALLATION 1 On V8 engines if fuel pump push rod has been removed install push rod and pipe fitting or fuel pump adapter using gasket sealer on gasket or pipe fitting M Install fuel pump using a new gasket and tighten securely Use sealer on fuel pump mounting bolt threads NOTE On V8 engines a pair of mechanical fingers or heavy grease may be used to hold fuel pump push rod up while installing fuel pump Ww Connect fuel pipes to pump 4 Start engine and check for leaks TIGHTEN TO 20 POUND FEET TIGHTEN TO 25 POUND FEET TIGHTEN TO 20 POUND FEET Fig 25C Fuel Pump 454 V8 TRUCK SUPP SERVICE 6M 74 ENGINE FUEL a n FUEL PUMP DIAGNOSIS CAMSHAFT DRIVEN FUEL PUMP Complete diagnosis of all possible causes of the trouble prior to replacement of the fuel pump will save time ex
84. Hinge sto3BOdys osi eiu 50 in Ib Roller to Bracket 20 ft Upper Left Hinge Door Half iuuat aaa oS 25 ft Upper Left Hinge Body Half SIDE DOORS Roller to Hinge i2 ce dO EEG 20 ft Guide Block to 40 in Door Hinges 318 amp Sec SS IS ESR SS 505 ILS EHE RI 30 ft Ib Lever Arm to Hinge Retaining Nut 120 in Door Hinge Access Hole Cover ue sme ers 18 in Ib Lever Retaining 5 40 in Door Lock Striker XIIe Rue 45 ft Ib Striker to 20 ft Door TOMO DORT 3 Rorre do ds qs 20 1 16 Rear Striker Bolt Body Mounted 45 ft Outside Door Handle 45 mie lb Striker Retaining Screws Body Mounted 90 in SEATS REAR DOOR Seat Belt to Seat u olx sek SAR Sees 37 ft Hinge Strap to 45 in lb Passenger and Drivers Hinge Strap Bracket to Body 45 in Ib Seat to Adjuster Mounting Bracket 18 ft Hinge to body and door 30 ft Ib S eatto yuy Ginea SR neg 18 ft Remote Control Retaining Screws 85 in lb Seat Riser to Floor 50 ft Latch to Door Retaining Screws 90 in lb Bench Seats Door Strikers to Body 90 in Ib Seat to Seat Support 18 ft Out
85. Lower 18 ft Rear Bench 06 14 Support to Seat 18 ft Support to Floor 40 ft Rear Bench 63 Support to Seat 150 in Support to Floor 18 in Folding Rear Seat 06 Support Asm to Floor 150 in Seat to Support 18 in lb lb lb in Ib in Ib lb in Ib in Ib in Ib in lb Ib in Ib Ib in Ib in Ib lb Ib Ib Ib Ib Ib Ib Ib lb lb Ib in Ib in lb in Ib in Ib TRUCK SUPP SPECS SPECIFICATIONS 3 BODY MOUNTING C K MODELS FT LBS G MODELS MIRRORS AND SUNSHADE SLIDING SIDE DOOR Inside Rear View Mirror to Bracket 15 in lb Remote Control front latch to Door 90 in Outside Rear View Mirror to Door Panel 25un lb Rear Lat h to Door vn Ses ua Oates 90 in Sunshade Support to Header Panel I5 in Ilb RearPlatet DoOr 42 2 22 eem 90 in Lower Front Roller and Roller Support Support to Door 24 ft Support to Roller Bracket 24 ft SIDE WINDOW SWINGOUT Roller to Roller Bracket 20 ft Catch to Roller 45 in MATCH eo eh enne xx 40 in Ib Upper Front Roller Bracket EatclistoGlassz e za ue rete RE 40 in Ib Brackett DOOL 2 osx Su QU qu xU 24 ft
86. M4ME carburetor models have a fixed idle air bypass system This consists of air channels which lead from the top of each carburetor bore in the air horn to a point below each throttle valve At normal idle extra air passes through these channels supplementing the air passing by the slightly opened throttle valves The purpose of the idle air bypass system is to allow reduction in the amount of air going past the throttle valves so they can be nearly closed at idle This reduces the amount of air flowing through the carburetor venturi to prevent the main fuel nozzles from feeding during idle operation The venturi system is very sensitive to air flow and where larger amounts of idle air are needed to maintain idle speed the fixed idle air bypass system is used As the primary throttle valves are opened from curb idle to increase engine speed additional fuel is needed to combine with the extra air entering the engine This is accomplished by the slotted off idle discharge ports As the primary throttle valves open they pass by the off idle ports gradually exposing them to high engine vacuum below the throttle valves The additional fuel added from the off idle ports mixes with the increasing air flow past the opening throttle valves to meet increased engine air and fuel demands Further opening of the throttle valves increases the air velocity through the carburetor venturi sufficiently to cause low pressure at the lower idle air bleeds As a
87. Months or 15 000 Miles 1 At First 6 Months or 7 500 Miles Then at 18 Month 22 500 Mile Intervals mio Every 12 Months or 15 000 Miles Every 18 Months or 22 500 Miles Ga Ww WIMP po po Of BY Every 22 500 Miles TRUCK SUPP SERVICE EXPLANATION OF COMPLETE VEHICLE MAINTENANCE SCHEDULE FOR SERIES 10 L 6 AND V 8 ENGINES AND LIGHT DUTY EMISSION SYSTEM Presented below is a brief explanation of each of the Vehicle Maintenance services NORMAL VEHICLE USE maintenance instructions contained in this maintenance schedule are based on the assumption that vehicle will be used as designed To carry passengers and cargo within the limitations indicated on the vehicle tire placard affixed to either the edge of driver s door or the inside of the glove box door e On reasonable road surfaces within legal operating limits e On a daily basis as a general rule for at least several miles On unleaded fuel Unusual operating conditions will require more frequent vehicle maintenance as specified in the respective sections included below Refer to the appropriate section of this manual for additional details on specific services A listing of recommended lubricants and fluids is included at the end of this listing SECTION A LUBE AND GENERAL MAINTENANCE 1 CHASSIS Lubricate all grease fittings in front
88. Rear Output Yoke Rear Output Seal Shims Input Shaft O Ring Input Shaft Pilot Bearings Differential Carrier Assembly Spring Washer Cup Lockout Clutch Spring Snap Ring Snap Ring Front Output Rear Brg Cover Front Output Rear Brg Front Output Drive Sprocket Gasket Fig 1F New Process Transfer Case Cross Section Magnet Drive Chain Gasket Brg Outer Ring Front Output Front Brg Front Output Shaft Seal Front Output Brg Retainer Rubber Spline Seal Locknut Front Output Yoke Countergear Countergear Spacers and Brgs Countergear Shaft Countergear Thrust Washer Gasket Brg Retainer Gasket Brg Outer Ring Input Gear Brg Input Gear Seals 2 Brg Snap Ring Input Gear Input Gear Brg Retainer TRUCK SUPP OVERHAUL MANUAL TRANSMISSION 7M 17 as DRO 34 TRUCK SUPP OVERHAUL 7M 18 MANUAL TRANSMISSION Adapter Input Gear Bearing Retainer Input Gear Bearing Retainer Gasket Input Gear Bearing Retainer Seals Bearing Outer Ring Bearing to Shaft Retaining Ring Input Gear Bearing Adapter to Selector Housing Gasket Range Selector Housing Range Box Cover Gasket Cover Selector Housing to Chain Housing Gasket Main Drive Input Gear Range Selector Sliding Clutch Shift Lever Lock Nut Range Selector Shift Lever Shift Lever Retaining Ring Lockout Shift Lever Detent P
89. SHOWN BRING THEM SLOWLY TOGETHER UNDER PRESSURE Fig 5G Spring Tension Comparison AUTOMATIC TRANSMISSION 7 5 acceptable non conforming modulator will cause the indicator to shift thus showing blue If white does not appear the modulator in question should be replaced TURBO HYDRA MATIC 400 475 TRANSMISSION INDEX Maintenance and 7 1 Transmission Fluid 7 1 Draining and Refilling Transmission eee 1 Detent Downshift Switch 1 1 Service Operations oid u s ha aa S auqa qasa 7 2 Transmission Replacement sese 7 2 MAINTENANCE AND ADJUSTMENTS TRANSMISSION FLUID Draining and Refilling Transmission The oil pan should be drained and filter replaced every 30 000 miles and fresh fluid added to obtain the proper level on indicator For vehicles subjected to heavy city traffic during hot weather or in commercial use when the engine is regularly idled for prolonged periods or when vehicle is used for towing oil pan should be drained and filter replaced every 15 000 miles Drain fluid immediately after operation before it has had an opportunity to cool WARNING Transmission fluid temperature can exceed 350 F DETENT DOWNSHIFT SWITCH 1 Install switch as shown in Figure 1L 2
90. SPECIFICATIONS 5 FRONT SUSPENSION BOLT TORQUE Ft Lbs CP 10 Lower Control Arm Shaft U Bolt 85 Upper Control Arm Shaft Nuts 10 Control Arm Rubber Bushings 140 Upper Control Arm Bushing Steel Lower Control Arm Bushing Steel Upper Ball Joint Nut 50 Lower Ball Joint Nut 90 Crossmember to Side Rail 65 Crossmember to Bottom Rail 100 CP 20 30 w Spacer 190 No Spacer 115 w Spacer 280 No Spacer 130 SS w Spacer 160 No Spacer 95 w Spacer 280 No Spacer 130 50 4 90 65 100 Crossmember Brake Support Struts L 60 Stabilizer Bar to Control Arm Stabilizer Bar to Frame Shock Absorber Upper End ANCHOR P Shock Absorber Lower End Brake Splash Shield to Knuckle Wheel Bearing Adjustment Wheel Bearing Preload 25 25 140 60 Zero Wheel Bearing End Movement Caliper Mounting Bolt Spring Front Eye Bolt w Spring Rear Eye Bolt Spring To Rear Shackle Bolt 001 005 001 005 35 25 25 60 LATE 55 65 65 Inner 35 Outer 50 Zero 001 010 35 90 120 In Lbs 120 In Lbs 120 In Lbs 130 25 120 In Lbs Zero 001 005 35 Spring To Axle U Bolt Spring Front Support to Frame Suspension Bumper Stabilizer to Spring Plate LO 50 E 150 i Plus additional torque to al
91. Screw Hose Clamp to Skirt Screw Line Ctamp to Frame Bolt 20 ft 16 P20 30 17 ft Ibs 35 ft Ibs 140 in 165 25 ft Ibs 25 ft lbs 150 in Ibs 25 ft 15 25 in 165 3 25 ft Ibs 45 ft lbs 100 Ibs 25 ft Ibs 25 ft Ibs 25 ft Ibs cm Ed UNE Ibs er Ibs in 18 ft Ibs in Ibs 18 ft Ibs 55 in Ibs 30 ft Ibs 150 in Ibs 55 in Ibs 20 ft 15 30 ft Ibs 50 in lbs 140 ft Ibs 22 ft Ibs 58 in Ibs 150 in Ibs 150 in Ibs 150 in Ibs 90 in Ibs 150 in Ibs P10 150 in Ibs 150 in Ibs 150 in bs 150 in Ibs 150 in 16 150 in Ibs 100 in 165 150 in Ibs CHE U 150 Ibs 18 ft Ibs Torque to seal or 100 in Ibs max Replace valve if it will not seal at 100 in Ibs x 25 ft Ibs 25 ft Ibs ENTRE l xx _ 7 25 ft lbs 235ft tbs 25 150 Ibs 150 Ibs 40 in bs Po 18 ft Ibs TRUCK SUPP SPECS SPECIFICATIONS 9 ENGINE SECTION 6 GENERAL DATA Displacement cu in Compression Ratio In Line Firing Order CYLINDER BORE Out of Production Round Service Produc Thrust Side 0005 Max Taper 0005 Max 1001 Max Service 005 Max PISTON r 0026 0036 0007 0013 0018 0028 uA 0045 Max
92. Service operations to the rear head or internal mechanism of the compressor should be performed with the compressor removed from the vehicle to insure that the necessary degree of cleanliness may be maintained Clean hands clean tools and a clean bench preferably covered with clean paper are of extreme importance An inspection should be made of the internal mechanism assembly to determine if any service operations should be performed A detailed inspection of parts should be made to determine if it is economically feasible to replace them Remove 1 Before proceeding with disassembly wipe exterior surface of compressor clean 2 oil in compressor should be drained and measured Assist draining by positioning compressor with oil drain plug down Record the amount of oil drained from the compressor 10 Remove four AIR CONDITIONING COMPRESSOR 1 11 HOLDING FIXTURE 1 9396 f Fig 24 Compressor Installed in Holding Fixture Invert compressor and Holding Fixture J 9396 with front end of compressor shaft facing downward Fig 24 Additional oil may leak from compressor at this time oil must be drained into containerso that TOTAL amount can be measured A liquid measuring cup may be used for this purpose Drained oil should then be discarded locknuts from threaded studs on compressor shell and remove rear head Tap uniformly around rear head if head is binding Fig 24 Wipe excess
93. TANG SPRING Fig 26 Choke System The thermostatic coil in the choke housing is calibrated to hold the choke valve closed when the engine is cold To close the choke valve depress the accelerator pedal completely to allow the idle speed screw to clear the steps on the fast idle cam At this point tension of the thermostatic coil will rotate the choke valve to the closed position and the idle speed screw will come to rest on the highest step of the fast idle cam During engine starting the high vacuum beneath the choke valve causes extra fuel to flow from the carburetor ports providing a rich mixture for quick engine starting When the engine starts and is running manifold vacuum is applied to the vacuum break diaphragm unit mounted on the carburetor air horn The diaphragm unit connected by linkage to the choke valve opens the choke valve a predetermined amount against coil tension so that the air fuel mixture will be lean enough so the engine will run without loading or stalling When the choke valve moves to the vacuum break position the fast idle cam will drop from the high step to a lower step when the throttle is opened The vacuum break unit is delayed in operation by an internal bleed check valve The delay check valve slows down further opening of the valve a few seconds until the engine will run on slightly leaner mixtures A choke closing assist spring is used on the vacuum diaphragm plunger stem The spring assists in
94. TERMINALS AND REPLACE IF DEFECTIVE CONNECT SHORT TESTER TO HARNESS AT BUZZER BROWN AND WHITE WIRES AND BODY 3ROUND TEST LIGHT ON TEST LIGHT OFF BUZZER CHECK FOR BREAK IN LAMP AND BUZZER CIRCUITS AND REPAIR REPAIR IBLACKI GROUND WIRE CONNECTION TO BODY REPAIR BROWN WIRE KEY OFF TEST LIGHT ON WITH R WAIT 12 MINUTES RECONNECT BODY HARNE INSTRUMENT PANEL MPER AND DISCONN THE DRIVER S BUCKLE BUZZER OPERATES BUZZER INOPERATIV REPLACE BUCKLE SWITCH REPAIR SHORT IN BONY amp Zi SISSVHD ANY AGO8 1V2IH12313 12 6 ELECTRICAL BODY AND CHASSIS PINK WHT STRIPE PINK WHT STRIPE TO IGNITION SWITCH DRIVER BUCKLE BUZZER 2 c r x a CONNECTORS SWITCH NORMALLY OPEN Fig 9 Seat Belt Reminder System Schematic INSTRUMENTS AND GAGES AMMETER VOLTMETER The ammeter for all light duty trucks has been cancelled for 1976 and is being replaced by a voltmeter The difference between the two is mainly that an ammeter shows the actual charging rate of the battery whereby a voltmeter indicates the condition voltage level of the charging system and battery Service replacement procedures are the same for voltmeter as for the ammeter WIRING DIAGRAMS Truck wiring diagrams are shown in 1976 Light Medium and Heavy Duty Truck Wiring Diagram Manual TRUCK SUPP SERVICE SECTION 14 BUMPERS Service procedures for the 1976
95. U X PUMP RETURN SPRING DISCHARGE CHECK BALL Fig 70 Accelerating Pump System TRUCK SUPP SERVICE The pump discharge check ball seats in the pump discharge passage during upward motion of the pump plunger so that air will not be drawn into the passage other wise a momentary acceleration lag could result During high speed operation a vacuum exists at the pump discharge jets A cavity just beyond the pump jets is vented to the top of the air horn outside the carburetor bores This acts as a suction break so that when the pump is not in operation fuel will not be pulled out of the pump jets into the venturi area This insures a full pump stream when needed and prevents any fuel pull over from the pump discharge passage CHOKE SYSTEM FIG 8Q The Quadrajet choke valve is located in the primary side of the carburetor It provides the correct air fuel mixture enrichment to the engine for quick cold engine starting and during the warm up period The choke system consists of a choke valve located in the primary air horn bore a vacuum break unit fast idle cam connecting linkage and a manifold mounted thermostatic coil The thermostatic coil is connected by a choke rod to the intermediate choke shaft and lever assembly Choke operation is controlled by the combination of intake manifold vacuum the off set choke valve temperature and throttle position The thermostatic coil part of the choke assembly located on the e
96. VALVE BEND CHOKE TO ADJUST CAM FOLLOWER ON SECOND STEP Fig 10Q Choke Rod Fast Idle Cam Adjustment 3 If adjustment is required support pump lever with screwdriver and bend pump lever 4 Check and adjust idle speed if required AIR VALVE DASHPOT ADJUSTMENT FIG 120 1 Completely seat choke vacuum break diaphragm using an outside vacuum source 2 With choke diaphragm seated and air valve fully closed measure the distance between the end of slot in vacuum break plunger lever and air valve using 015 gauge 3 Bend air valve dashpot rod as shown in figure 12Q if required to adjust ENGINE FUEL 6 61 3 GAUGE FROM TOP OF CHOKE VALVE WALL NEXT TO VENT STACK TO TOP OF PUMP STEM AS SPECIFIED 2 IN SPECIFIED HOLE OF PUMP LEVER 4 SUPPORT LEVER WITH SCREWDRIVER WHILE BENDING LEVER THROTTLE VALVES COMPLETELY CLOSED BEND SECONDARY CLOSING TANG AWAY TO CLOSE PRIMARY VALVES THEN RE ADJUST Fig 110 Rod Adjustment VACUUM BREAK ADJUSTMENT FIG 13Q Before adjusting the vacuum break check and or adjust the fast idle fast idle cam and air valve dashpot 1 Seat vacuum break diaphragm using outside vacuum source 2 Open throttle and place fast idle cam follower lever on high step of fast idle cam 3 Lightly rotate choke coil lever counterclockwise until end of rod is in end of slot in lever 4 Gauge distance bet
97. When replacing shaft seal assembly it will be necessary to discharge the refrigerant from the system before replacing shaft seal assembly or removing compressor from vehicle 1 Discharge the system and remove clutch plate and hub assembly as described under Compressor Clutch Plate and Hub Assembly 2 Remove shaft seal seat retainer ring using snap ring pliers J 5403 3 Thoroughly clean the inside of compressor neck area surrounding compressor shaft seal seat and shaft to remove all dirt and foreign material before removing Seal seat 4 nsert seal seat remover and install tool J 23128 Fig 74 over the shaft into the recessed area of seal seat and tighten tool clockwise to securely engage knurled tangs of tool with the seal seat Remove seal seat with a twisting and pull motion Discard seat 5 Insert seal remover and installer J 9392 Fig 75 over shaft and engage shaft seal by pressing downward on tool to overcome shaft seal spring pressure and turn tool clockwise to engage seal assembly tabs with tangs of tool Remove seal assembly by pulling straight out from compressor shaft Discard seal TRUCK SUPP OVERHAUL J9401 CLUTCH PLATE AND HUB ASSEMBLY Fig 7 1 Removing Clutch Plate and Hub Assembly CLUTCH PLATE CLUTCH ROTOR Fig 72 Installing Shaft Key 6 Remove seal seat O ring from compressor neck using tool J 9553 Discard O ring Installation Inspect the inside of compressor neck and shaf
98. adjust choke intermediate rod fig 29 Engine flooded Carburetor flooding See procedure under Engine cranks will not start No fuel in carburetor 1 Check fuel pump Run pressure and volume test 2 Check float needle for sticking in seat or bindina float Leaking float bowl Fill bowl with fuel and look for leaks TRUCK SUPP SERVICE UT l _ _ C C C ENGINE FUEL 6M 53 Problem POOR FUEL ECONOMY POSSIBLE CAUSE CORRECTIVE ACTION Engine needs complete tune up Check engine compression Examine spark plugs if dirty or improperly gapped clean and or replace Check ignition point dwell condition readjust ignition points if necessary and check and reset ignition timing Clean or replace air cleaner element if dirty Check for restricted exhaust system and intake manifold for leakage make sure all vacuum hoses are connected correctly Choke valve not fully opening 1 Clean choke and free up linkage 2 Check intermediate choke rod for proper adjustment Reset to specifications fig 29 Fuel leaks Check fuel tank fuel lines and fuel pump for any fuel leakage Remove carburetor air horn and gasket Adjust metering rod Main metering rod not adjusted to specification epee as specified in carburetor overhaul section Metering rod bent or incorrect part Main metering jet Replace as necessary as specified in carburetor overhaul defective loose or incorrect part section Powe
99. and air pressure fails to clean the idle passages If the idle mixture needles are removed refer to Service Section for adjustment procedure If necessary to remove the idle mixture needle destroy plastic limiter SPRING FUEL INLET NUT FILTER Fig 17MQ Fuel Filter ATTACHING SCREWS Fig 18MQ Removing Throttle Body cap Do not install a replacement cap as a bare mixture Screw is sufficient to indicate that the mixture has been re adjusted CLEANING AND INSPECTION 1 Thoroughly clean carburetor castings and metal parts in an approved carburetor cleaner such as Carbon X X 55 or its equivalent CAUTION The throttle lever actuator electric choke rubber parts filter plastic parts pump plunger and choke vacuum break s should not be immersed in carburetor cleaner However the throttle valve shafts will withstand normal cleaning in carburetor cleaner __ INSULATOR GASKET Fig 19 Insulator Gasket TRUCK SUPP OVERHAUL Blow out all passages in castings with compressed air CAUTION Do nor pass drills through jets or passages Examine float needle and seat for wear Replace if necessary with new float needle and seat assembly Inspect upper and lower surfaces of carburetor castings for damage Inspect holes in levers for excessive wear or out of round conditions If worn levers should be replaced Examine fast idle cam for wear or damage Check air valv
100. and remove valve 4 Install valve reversing steps 1 through 3 TRUCK SUPP SERVICE EMISSION CONTROL SYSTEMS 6 7 DIAGNOSIS CHECKING EFE SYSTEM 1 With engine cold position transmission in neutral or park and apply parking brake 2 Start engine and observe movement of actuator rod and exhaust heat valve Valve should move to its closed position 3 If valve does not close disconnect hose at actuator and check for vacuum e If there is vacuum replace actuator e If there is no vacuum disconnect hose at TVS to vacuum source If there is vacuum at hose replace TVS e If there is no vacuum check for deteriorated hose and vacuum source to determine lack of vacuum 4 When coolant reaches 180 F small block V8 or 454 V8 or oil reaches 150 F six cylinder the exhaust heat valve should move to its open position If valve does not move disconnect hose at actuator and check for vacuum e If there is vacuum replace TVS e If there is no vacuum replace actuator THROTTLE RETURN CONTROL SYSTEM TRC GENERAL A throttle return control system TRC is used on a Light Duty Truck in California with V8 engine and heavy duty emissions When vehicle is coasting against engine the control valve will be open to allow vacuum to operate throttle lever actuator The throttle lever actuator then pushes throttle lever slightly open thus reducing hydro carbon emission during coast down When manifo
101. around main metering rods and beneath the power piston hanger Position gasket over the two dowel pins on the float bowl Carefully lift one corner of the air horn gasket and install pump plunger in the pump well by pushing the plunger to the bottom of the well against return spring tension While holding in this position align pump plunger stem with hole in gasket and press gasket in place Air Horn l If removed install choke shaft choke valve and two attaching screws Tighten screws securely and stake lightly in place Check choke valve for freedom of movement and proper alignment before staking screws in place Air Horn to Bowl Installation 1 Holding down on air horn gasket at pump plunger location carefully lower air horn assembly onto float bowl making sure that the bleed tubes accelerating well tubes pull over enrichment tubes if used and pump plunger stem are positioned properly through the holes in the air horn gasket CAUTION Do not force the air horn assembly onto the bowl but rather lightly lower in place Install two long air horn screws five short screws and two coutersunk screws into primary venturi area All air horn screws must be tightened evenly and securely See Figure 5MQ for proper tightening sequence Install vacuum break diaphragm rod into the slot in lever on the end of the air valve shaft Then install the other end of rod into hole in the front vacuum break diaphrag
102. be visible at inner and outer ends of adjuster sleeve when assembled to steering knuckle NOTE Locate clamps within tolerance shown Fwo HORIZONTAL LINE CAUTION Clamp must be between amp clear of dimples before torquing nut REARWARD ROTATION G SERIES NOTE Equal thread lengths must be visible at inner and outer ends of adjuster sleeve when assembled to steering knuckle NOTE Locate clamps within SLOT HORIZONTAL LINE NOTE Slot in adjuster sleeve must not be within this area of clamp jaws ADJUSTER SLEEVE tolerance shown CAUTION Clamp must be between amp clear of dimples before torquing nut C K SERIES knuckle CAUTION Clamp must be between amp clear of dimples before torquing nut P SERIES NOTE Slot in adjuster NOTE Locate clamps within tolerance oe 450 Fwo Er SAE REARWARD I ROTATION NOTE Slot in adjuster sleeve must not be within this area of clamp jaws view A NOTE Equal thread lengths must be visible at inner and outer ends of adjuster sleeve when assembled to steering VERTICAL LINE SLOT ADJUSTER SLEEVE sleeve must not be within this area of clamp jaws REARWARD 450 ROTATION NS VIEW A Fig 5 Tie Rod Clamps TRUCK SUPP SERVICE STEERING 9 7 305 350 400 V 8 10 30 K 10 20 G 10 C 10 P 2030 350 V 8 MOTOR HOME G 20 30 C 10 30 K 20 P 20 30 Fi
103. bearing on clutch gear shaft using tool J 24433 fig 22R Install smaller snap ring on clutch gear shaft Position bearing retainer gasket on case Be sure cut out in gasket is aligned with oil return hole in case Install front bearing retainer and tighten attaching bolts to 30 to 36 foot pounds of torque Be sure to index cap to case with alignment marks and that oil return slot in cap is aligned with oil return hole in case Install large snap ring on rear bearing Install rear bearing on output shaft by hand Drive bearing onto shaft and into case with tool J 22609 make sure snap ring groove is facing rear of shaft fig 23R Install smaller snap ring on output shaft to hold rear bearing in place 3T wa 34 35 Engage speedometer gear retainer in hole provided in output shaft with retainer loop forward slide speedometer gear over output shaft and into position fig 24R Position extension housing gasket on case and install extension housing to case Tighten bolts to 42 to 50 foot pounds torque Install expansion plug in Second Third shift rail bore in front of case Be sure plug is fully seated in bore and is approximately 1 16 inch below front face of case Install upper detent plug in detent bore then install long detent spring on top of plug Install transmission fill plug and tighten 10 to 20 foot pounds torque Install top cover and gasket on case and secure with attaching bolts
104. block to corresponding holes in cover fig 3R 7 Remove the two 1 4 20x 1 2 screws previously used to draw up cover and install remaining cover screws 8 Complete installation as outlined in the 1974 Light Truck Service Manual TRUCK SUPP SERVICE 6 4 ENGINE Fig 2R Installing Front Cover and Seal DOWEL PIN 4 WW ONE AT EACH SIDE Fig 3R Aligning Cover to Dowel Pins DIAGNOSIS ENGINE FAILS TO START Clean and tighten loose battery terminal connections Using battery hydrometer check specific gravity if low recharge battery Check battery state of charge indicator on Freedom type battery Check for broken or loose ignition wires and or ignition switch and repair or replace as necessary Remove moisture from spark plug wires and or distributor cap Inspect condition of distributor cap and rotor Replace if damaged or cracked Check inspect and regap spark plugs Replace as necessary Check for weak or faulty HEI System Coil as outlined in Section 6Y of this manual Check carburetor float level operation of secondary vacuum break solenoid air valve and enrichment system m as outlined in Section 6M of this manual Inspect carburetor fuel filter for presence of water and or impurities Correct as necessary Check choke mechanism for proper operation Any binding condition which may have developed due to petroleum gum formation on the choke sh
105. boost venturi area The pump plunger is spring loaded the upper duration spring is balanced with the bottom pump return spring so that a smooth sustained charge of fuel is delivered during acceleration The pump discharge check ball prevents any pull over or discharge of fuel from the pump jet when the accelerator pump is not in operation It also keeps the pump discharge passage filled with fuel to prevent pump discharge lag pump does not require adjustment in service as it is preset during manufacture CHOKE SYSTEM Fig 7 The purpose of the choke system is to provide a richer mixture for cold engine starting and operation Richer than normal mixtures are required because vaporized fuel has a tendency to condense on cold engine parts This occurs on the inside area of the intake manifold and cylinder heads thereby decreasing the amount of combustible mixture available in the engine cylinders The model carburetor is equipped with a fully automatic choke control The thermostatic coil is mounted on the head and is connected by a link to the lever on the choke valve shaft The vacuum break units are diaphragm operated and externally mounted on the air horn casting The choke system operates as follows when the engine is cold prior to starting depressing the accelerator pedal to the floor opens the carburetor throttle valve This allows tension from the thermostatic coil to close the choke valve and also rotates th
106. carburetor cleaner Fig 12MQ Removing Aneroid Cavity Insert TRUCK SUPP OVERHAUL PUMP DISCHARGE CHECK BALL RETAINER AND CHECK BALL PRIMARY METERING JETS SECONDARY METERING ve JETS ay Fig 13MQ Float Bowl Jets 12 Remove vacuum break rod by holding down on fast idle cam hot idle position move end of vacuum break rod away from float bowl then disengage rod from hole in intermediate choke lever Choke 1 Remove three attaching screws and retainers from choke cover and coil assembly Then pull straight outward and remove cover and coil assembly from choke housing Remove choke cover gasket if used Fig 14MQ Rear Vacuum Break CARBURETOR 6M 15 On M4MC hot air choke model it is not necessary to remove baffle plate from beneath the thermostatic coil Distortion of the thermostatic coil may result if forced off the center retaining post on the choke cover Remove choke housing assembly from float bowl by removing retaining screw and washer inside the choke housing Fig 15MQ The complete choke assembly can be removed from the float bowl by sliding outward Remove secondary throttle valve lock out lever from float bowl Fig 16MQ Remove lower choke lever from inside float bowl cavity by inverting bowl Remove plastic tube seal from choke housing Fig 16MQ CAUTION Plastic tube seal should not be immersed in carburetor cleaner To disassemb
107. carburetor idle speed screw to specifications 2 Hold choke valve wide open with cam follower lever off steps of fast idle cam 3 Using specified gauge measure clearance between slot in secondary throttle valve pick up lever and secondary actuating rod 4 Bend secondary closing tang on primary throttle lever as shown to adjust TRUCK SUPP SERVICE CHOKE VALVE WIDE OPEN FOLLOWER OFF STEPS OF FAST IDLE CAM ENGINE IDLE SET TO PROPER IDLE R P M SPECIFIED CLEARANCE Fig 16Q Secondary Closing Adjustment Secondary Opening Adjustment 1 Lightly open primary throttle lever until link just contacts tang on secondary lever 2 With link against tang the link should be in center of slot in the secondary lever 3 Bend tang on secondary lever as shown if necessary to adjust Air Valve Spring Wind Up Adjustment Fig 17Q This adjustment is made only when replacing air valve During service maintenance or normal overhaul do not 2 WITH LOCK SCREW LOOSENED AND WITH AIR VALVE CLOSED TURN ADJUSTING SCREW SPECIFIED NUMBER OF TURNS AFTER SPRING CONTACTS PIN 3 TIGHTEN Lock SCREW TENSION ADJUSTING SCREW Fig 17Q Air Valve Spring Wind Up Adjustment ENGINE FUEL 6M 63 remove air valve Remove vacuum break diaphragm unit and air valve dashpot rod 2 Loosen lock screw using special hex wrench 3 Turn tension adjusting screw counterclockwise until air valve opens part wa
108. certain that it is properly seated in ring groove 3 Install pulley and bearing assembly as described in UNIVERSAL HANDLE J 8092 PULLEY amp BEARING INSTALLER J 9398 PULLEY ASSEMBLY Fig 14 Removing Bearing from Pulley Assembly THIS RIDGE OF TOOL MUST BE UP WHEN INSTALLING BEARING PULLEY AND BEARING INSTALLER J 9481 SUPPORT BLOCK J 21352 Fig 15 Installing Bearing on Pulley AIR CONDITIONING COMPRESSOR 1 7 Compressor Pulley and Bearing Asm Replacement procedure 4 Install clutch plate and hub assembly as described in Compressor Clutch Plate and Hub Asm Replacement procedure CLUTCH COIL AND HOUSING ASSEMBLY Remove 1 Remove clutch plate and hub assembly as described in Compressor Clutch Plate and Hub Asm Removal procedure 2 Remove pulley and bearing assembly as described in Compressor Pulley and Bearing Asm Removal procedure 3 Note position of terminals on coil housing and scribe location on compressor front head casting 4 Remove coil housing retaining ring using Snap Ring Pliers J 6435 26 Fig 16 5 Lift Coil and Housing assembly off compressor Replace 1 Position coil and housing assembly on compressor front head casting so that electrical terminals line up with marks previously scribed on compressor Fig 17 2 Align locating extrusions on coil housing with holes in front head casting 3 Install coil housing retainer ring with flat sid
109. closely and replaced if they show wear Inspect countershaft and reverse idler shaft at the same time replace if necessary Replace all worn washers Gears 1 Inspect all gears for excessive wear chips or cracks and replace any that are worn or damaged 2 Check both clutch sleeves to see that they slide freely on their hubs NOTE ALIGN ROLL PIN HOLE WHEN INSTALLING DUMMY SHAFT TOOL J 25232 COUNTERSHAFT Fig 5bR Removing Countershaft ALIGNMENT MARKS Fig 6R Removing Front Bearing Retainer REPAIRS Synchronizer Keys and Spring Replacement 1 Mark hub and sleeve so they can be matched upon reassembly 2 Push the hub from the sliding sleeve the keys and the springs may be easily removed 3 Install one spring into second third hub Be sure spring covers all three key slots in hub Align second third sleeve to hub using marks made during disassembly and TRUCK SUPP OVERHAUL MANUAL TRANSMISSION 7 5 BEARING REMOVER TOOL J 8157 01 f PULLER SCREWS Fig 8R Removing Rear Bearing start sleeve onto hub Place the three keys into hub slots and on top of spring then push sleeve fully onto hub to engage keys in sleeve fig 14 Install remaining spring in exact same position as first spring Ends of both spring must cover same slots in hub and not be staggered FIRST REVERSE SLEEVE AND GEAR IN FORWARD POSITION TO CLEAR CASE Fig 1OR Removing Output Shaft
110. closing fuel from the float bowl enters the pump well through a slot in the well It flows past the synthetic pump cup seal into the bottom of the pump well The pump cup is the floating type The cup moves up A SABATO DISCHARGE PASSAGE DISCHARGE BALL RETAINER DISCHARGE CHECK BALL PUMP RETURN SPRING CUP SEAL PUMP PLUNGER EXPANDER SPRING Fig 42 Accelerating Pump System ENGINE FUEL 6M 37 and down on the pump plunger head see inset When the pump plunger is moved upward the flat on the top of the cup unseats from the flat on the plunger head and allows free movement of fuel through the inside of the cup into the bottom of the pump well This also vents any vapors which may be in the bottom of the pump well so that a solid charge of fuel can be maintained in the fuel well beneath the plunger head When the throttle valves are opened the connecting linkage forces the pump plunger downward The pump cup seats instantly and fuel is forced through the pump discharge passage where it unseats the pump discharge check ball and passes on through the passage to the pump jets located in the air horn where the fuel sprays into the venturi of each bore An expander garter spring located beneath the pump plunger cup is used to assist in maintaining constant pump cup to pump well contact for good pump fuel delivery metal baffle is installed in the slot in the pump well to prevent fuel slosh into the pu
111. coil lever adjustment must be made 3 Then turn the fast idle screw in an additional 3 turns before making the following adjustment to adjust 1 Perform fast idle adjustment 4 Recheck fast idle speed on the vehicle setting to specifications listed on the underhood Vehicle Emission Control Information label On Vehicle 3 Place the fast idle cam follower on the second step of the fast idle cam firmly against the shoulder of the high 1 Connect a tachometer to the engine step 2 Remove coil assembly from choke housing by removing the three retaining screws and clips TRUCK SUPP SERVICE 6M 42 ENGINE FUEL Qa LOOSEN THREE RETAINING SCREWS AND REMOVE THE THERMOSTATIC COVER AND BETWEEN UPPER 5 D TANG COIL ASSEMBLY FROM CHOKE HOUSING OP CHORE VALVES ON FAST IDLE CAM CHOKE VALVE E AIN ROHN WALL TO ADJUST AOD AT BOTTOM CLOSED OF SLOT i 6 AT THIS POINT TO ADJUST ISEE INSET NOTE HOLD GAUGE NOTE MAKE SURE TANG VERTICALLY LAYS AGAINST CAM AFTER BENDING 2 PUSH UP ON THERMOSTATIC COIL TANG COUNTERCLOCKWISE UNTIL CHOKE VALVE IS CLOSED 5 LOWER EDGE OF LEVER SHOULD JUST CONTACT SIDE OF PLUG GAUGE 3 CLOSE CHOKE BY 7 PUSHING UPWARD ON M CHOKE COIL LEVER i C 2 PLACE CAM FOLLOWER im A ON SECOND STEP OF NEXT TO HIGH STEP INSERT SPECIFIED PLUG GAUGE Fig 46 Choke Coil Lever Adjustment 4 Close the choke valve
112. compressor from Holding Fixture J 9396 place Internal Assembly Support Block J 21352 over oil pump end of shaft and holding Support Block in position with one hand lift compressor from Holding Fixture with OIL PICK UP TUBE REMOVER J 5139 NN OIL PICK UP TUBE Fig 28 Removing Oil Pick Up Tube other hand Invert compressor and position on bench with Internal Assembly Support Block resting on bench 15 Lift front head and compressor shell assembly up leaving internal mechanism resting on Internal Assembly Support Block CAUTION prevent damage to shaft DO NOT TAP ON END OF COMPRESSOR SHAFT to remove internal mechanism If mechanism will not slide out of compressor shell tap on front head with a plastic hammer 16 Rest compressor shell on its side and push front head assembly through compressor shell being careful not to damage sealing areas on inner side of front head Discard O ring It may be necessary to tap on outside of front head using a plastic hammer to overcome friction of O ring seal between front head and compressor shell 17 Wipe excess oil from sealing surfaces on front head casting webs and examine sealing surface If any surface damage is observed the head should be replaced 18 Remove front discharge valve plate assembly and front suction reed plate Examine reeds and seats Replace necessary parts 19 Remove suction cross over cover by prying with screwdriver between cylinder cast
113. cylinder bore This keeps the valves off of their seat and opens communication between the cylinder bore and the reservoir The initial forward movement of the pistons permits the compensating valves to seat which closes communication between the pressure chambers in the cylinder bore and the reservoirs Any further movement of the pistons builds up pressure which is transmitted to the calipers or wheel cylinders Disassembly 1 Remove the reservoir cover and diaphragm and drain the fluid from the reservoir 2 Remove the four bolts that secure the body to the reservoir using Socket J 25085 3 Remove the small O ring and the two compensating valve seals from the recessed areas on the bottom side of the reservoir NOTE Do not remove the two small filters from the inside of the reservoir unless they are damaged and are to be replaced 4 Depress the primary piston using a tool with a smooth rounded end Then remove the compensating valve poppets and the compensating valve springs from the compensating valve ports in the master cylinder body WARNING It air pressure 1s used to remove the secondary piston place the open end of the cylinder bore approximately 1 from a padded workbench or other surface to catch the piston when it comes out of the bore Apply low air pressure very carefully to ease the piston out of the bore Never point the open end of the bore at anyone when applying air pressure The piston may come out of
114. described in Compressor Clutch Plate and Hub Asm Replacement Procedure TRUCK SUPP OVERHAUL 1 6 AIR CONDITIONING COMPRESSOR Fig 9 Checking Air Gap SNAP RING PLIERS J 6435 PULLEY d RETAINER ASSEMBLY Fig 10 Removing Pulley Retainer Ring PULLEY BEARING Remove 1 Remove clutch plate and hub assembly as described Compressor Clutch Plate and Hub Asm Removal procedure 2 Remove pulley and bearing assembly as described in Compressor Pulley and Bearing Asm Removal procedure 3 Remove pulley bearing retainer ring with a small screwdriver or pointed tool Fig 13 4 Place pulley and bearing assembly on inverted Support Block J 21352 and using Pulley Bearing Remover J 9398 with Universal Handle J 8092 drive Bearing assembly out of pulley Fig 14 Replace 1 Install new bearing in pulley using Pulley and Bearing Installer J 9481 with Universal Handle J 8092 Fig 15 The Installer will apply the force to the outer race of the bearing PULLEY AND PULLER PILOT EP BEARING 476408 ASSEMBLY UNIVERSAL HANDLE J 8092 PULLEY AND BEARING INSTALLER J 9481 BEARING RETAINER Fig 13 Removing Pulley and Bearing Retainer Ring CAUTION DO NOT CLEAN NEW BEARING ASSEMBLY WITH ANY TYPE OF SOLVENT Bearing is supplied with correct lubricant when assembled and requires no other lubricant at any time TRUCK SUPP OVERHAUL 2 Install bearing retainer ring making
115. designed to maintain a pressure of at least 15 psi in the cooling system once the engine has attained operating temperature The pressure cap relief valve located in the cap allows excessive pressure to escape through the overflow hose into a coolant recovery bottle Using a J 24460 Cooling System Pressure Tester or equivalent a J 23699 adapter and a J 23636 hose gauge check the system for leaks in the following manner 1 Make a visual check of hoses and hose connections for leaks and tighten clamps as required Using normal precautions carefully remove the radiator cap NEVER REMOVE RADIATOR CAP WHEN ENGINE IS HOT Wash the cap with clean water until gaskets appear clean Test cap using J 24460 Tester Follow instructions furnished with the tester If cap will not hold pressure within specified band replace with a new radiator cap Clean and inspect the radiator filler neck The coolant level in the radiator should be within a 1 2 inch of the filler neck Fill the radiator to this level with 50 percent ethylene glycol solution and replace the radiator cap making sure it is on completely with the locking tangs against the stops Install Hose Gauge J 23636 on upper radiator hose Install Adapter J 23699 on Pressure Tester J 24460 Remove coolant recovery hose from radiator neck nipple and connect hose from Adapter J 23699 Pump system to 15 psi and watch for a pressure drop on pump gauge
116. discharge nozzles It begins to feed fuel when the idle system can no longer meet the engine requirements The main metering system consists of main metering jets vacuum operated metering rods main fuel well main well air bleeds fuel discharge nozzles and triple venturi The system operates as follows During cruising speeds and light engine loads engine manifold vacuum is high Manifold vacuum holds the power piston down against spring tension in contact with the adjustable part throttle screw and the larger diameter of the metering rod is in the main metering jet orifice Fuel flow from the float bowl is metered between the metering rods and the main metering jets As the primary throttle valves are opened beyond the off idle range allowing more air to enter the engine manifold air velocity increases in the carburetor venturi This causes a drop in pressure in the large venturi which is increased many times in the double boost venturi Since the low pressure vacuum is now in the smallest boost venturi fuel flows from the main discharge nozzles as follows TRUCK SUPP SERVICE MAIN WELL AIR BLEEDS MAIN DISCHARGE NOZZLE POWER PISTON J Y D BOOST VENTURII MAIN FUEL WELL THROTTLE VALVE PART THROTTLE 2 ADJUSTMENT SCREW CHANNEL MAIN METERING JET Fig 40 Metering System Fuel flows from the float bowl through the main metering jets into the main fuel well and is bled with air from the v
117. electronic type Leak Detector Correct any leak found Remove and discard the shaft nut 7 Remove any excess oil resulting from installing the new seal parts from the shaft and inside the compressor neck 8 Install the new absorbent sleeve by rolling the material into a cylinder overlapping the ends and then slipping the sleeve into the compressor neck with the overlap towards the top of the compressor With a small screwdriver or similar instrument carefully spread the sleeve until the ends of the sleeve butt at the top vertical centerline 9 Position the new metal sleeve retainer so that its flange face will be against the front end of the sleeve Pulley Puller Pilot J 9395 See Fig 11 may be used to install the retainer Press and tap with a mallet setting the retainer and sleeve into place retainer should be recessed approximately 1 32 from the face of the compressor neck See Fig 21 10 Reinstall the clutch plate and hub assembly as described in Compressor Clutch Plate and Hub Asm Replacement procedure Some compressor shaft seal leaks may be the result of mispositioning of the axial plate on the compressor shaft The mispositioning of the axial plate may be caused by improper procedures used during pulley and driven plate removal pounding collisions or dropping the compressor If the axial plate is mispositioned the carbon face of the shaft seal assembly may not contact the seal seat and the rear
118. engine idle or hot soak the valve will be pushed off its seat allowing the pressure to be relieved there by preventing fuel from being forced from the float bowl into the engine IDLE SYSTEM Fig 3 The purpose of the idle system is to control fuel mixtures to the engine during idle and low speed operation The idle system is needed during this period because air requirements of the engine are not great enough to obtain efficient metering from the main discharge nozzle and venturi system The idle system consists of a removable idle tube idle passages idle channel restriction idle air bleeds slotted off idle port vapor canister purge ports exhaust gas recirculation E G R ports and passages idle mixture adjusting needle and the idle mixture discharge hole During curb idle the throttle valve is held slightly open by the idle stop solenoid The small amount of air which passes between the throttle valve and bore is regulated by solenoid to provide the correct engine idle speed Since the engine requires very little air and fuel for idle and low speed operation fuel is mixed by direct application of engine manifold vacuum to the idle discharge hole just below the throttle valve With the idle discharge hole in a very low pressure area and the fuel in the float bowl vented to atmosphere fuel flows through the idle system as follows Atmospheric pressure forces fuel from the float bowl down through the main metering jet into
119. fast idle cam rubber band may be used for this purpose 3 Gauge between upper edge of choke valve and air horn wall 4 Bend tang on fast idle lever as shown to adjust CAUTION Check to be sure tang fast idle lever Is contacting center point of fast idle cam after adjustment SECONDARY THROTTLE VALVE LOCK OUT ADJUSTMENT Fig 54 Secondary Lock Out Lever Clearance 1 Hold choke valve and secondary throttle valves closed 2 Using 015 plug gauge measure clearance between lock out pin and lock out lever as shown 3 If necessary bend lock out pin at point shown to obtain 015 clearance Opening Clearance 4 Hold choke valve wide open by pushing down on tail of fast idle cam 5 Hold secondary throttle valves slightly open TRUCK SUPP SEAVICE CHOKE VALVE PUSH DOWN ON TAIL OF CAM ISTEP 2 CHOKE VALVE CLOSED THROTTLE VALVES CLOSED BEND PIN TO ADJUST 015 MAX CLEARANCE HOLD CHOKE VALVE WIDE OPEN BY PUSHING DOWN ON TAIL OF FAST IDLE CAM CHECK LOCKOUT PIN FOR CLEARANCE Fite EKO or pind Qa GAUGE FOR CLEARANCE CHECK FOR NO BURRS AFTER FILING SECONDARY LOCKOUT 2 OPENING CLEARANCE ECONDARY LOCKOUT LEVER SIDE CLEARANCE 5 J Fig 54 Secondary Throttle Valve Lock Out Adjustment 6 Using 015 plug gauge measure clearance between end of lock out pin and toe of lock out lever as shown 7 If necessary file off end of lock out pin to obtain 015 cleara
120. final adjustment by turning horizontal adjusting screw in a clockwise direction Repeat steps 9 thru 11 for other aimer Make sure vertical dial is at zero NOTE A zero setting is generally required Some state or local authorities have special requirements Consult those authorities and use the special requirement as required Turn headlamp vertical screw fig 1 until the top level vial bubble registers in the centered level position Repeat steps 13 and 14 for opposite aimer and headlamp 16 Recheck target alignment on both aimers and readjust horizontal aim if necessary 17 Remove aimers by holding aimer securely with one hand while pressing the vacuum release button located on locking handle of aimer with the other hand If headlamp aiming equipment is not available use procedure described in Section 12 of 1974 Service Manual 7 CIRCULAR HEADLAMP RECTANGULAR HEADLAMP ADAPTER J 25300 4 ADAPTER J 25300 3 9 3 5 CIRCULAR HEADLAMP ADAPTER J 25300 5 Fig 5 Headlamp Adapters TRUCK SUPP SERVICE n G p p na 12 4 ELECTRICAL BODY AND CHASSIS HEADLAMP ADAPTER P NC LEVEL VIAL VIEWING PORT TARGETS MUST FACE EACH OTHER HEADLAMP AIMER HEADLAMP AIMER J 25300 2 2 25300 1 Fig 6 Headlamp Aiming Typical SERVICE OPERATIONS HEADLAMPS WARNING BUZZER 2 Disconnect electrical connector from IGN Ignition
121. flat steel clutch plates b Models CG CJ CM CP CR and CT Oil and install five 5 composition faced and five 5 flat steel clutch plates starting with a flat steel plate and alternating composition faced and flat steel clutch plates c Models CL and CZ Oil and install six 6 composition faced and six 6 flat steel clutch plates starting with a flat steel plate and alternating TRUCK SUPP OVERHAUL 7A 10 AUTOMATIC TRANSMISSION composition faced and flat steel clutch plates NOTE All direct clutch flat steel clutch plates are the thick 0915 type The model CL direct clutch composition faced lates are different from the other models Refer to parts catalog book for correct usage Assembly procedure Step number 11 should read 11 Install the intermediate clutch outer race with a clockwise turning motion NOTE Intermediate roller clutch is not released for the CL and CZ models The sprag assembly is released for these models CENTER SUPPORT The procedure for disassembly inspection and assembly remains the same with the following exception Assembly Assembly procedure Step number 7 should read 7 Install four 4 oil seal rings on the center support NOTE When installing teflon oil seal rings make sure slit ends are assembled in same relation as cut Fig 13B Also make sure oil seal rings are seated in ring grooves to prevent damage to rings during re assembly of mating parts over rings Ret
122. float needle valve operation Replace as necessary Free up or replace as necessary It is absolutely necessary that all vacuum hoses and gaskets are properly installed with no air leaks The carburetor and manifold should be evenly tightened to specified torque Check engine compression Examine spark plugs if dirty or improperly gapped clean and re gap or replace Check ignition point dwell condition readjust ignition points if necessary and check and reset ignition timing Clean or replace air cleaner element if dirty Check for restricted exhaust system and intake manifold for leakage make sure all vacuum hoses are connected correctly 1 Clean choke and free up linkage 2 Check choke coil rod for proper adjustment Reset to specifications Check fuel tank fuel lines and fuel pump for any fuel leakage Free up or replace as necessary 1 Check for dirt in the needle and seat Test using suction by mouth or needle seat tester If defective replace needle and seat assembly with factory matched set 2 Check for loaded float 3 Re set carburetor float as specified in carburetor overhaul section 4 excessive dirt is present in the carburetor bowl the carburetor should be cleaned Fuel being pulled from accelerator system into venturi through pump jet Air bleeds or fuel passages in carburetor dirty or plugged Run engine at RPM where nozzle is feeding fuel Observe pump jet If fuel is
123. fluid in the gear The steering gear adjustment is made only as a correction and not as a required periodic adjustment 1974 Light Duty Truck Service Manual Section 9 an improperly adjusted over center preload could cause a To properly adjust the power steering gear the assembly MUST be removed from the vehicle and adjustments per formed as outlined in the 1974 Overhaul Manual Section 9 procedure as outlined under Power Steering Gear in the TRUCK SUPP SERVICE 9 2 STEERING Key No Part Name 1 COLUMN ASM 2 HOUSING ASM 3 RACK ASM 4 SPRING 5 SECTOR 6 SHAFT 7 CLIP 8 SWITCH 9 BEARING 10 WASHER 11 SCREW 4 12 RETAINING RING 13 NUT 14 COVER ASM SHIPPED SEPARATELY 15 RING 16 LOCK 17 CAM ASM 18 SPRING SCREW 3 Key No Part Name 20 SWITCH ASM 21 PROTECTOR WIRE 22 HOUSING 23 CUP 24 BOLT ASM 25 WASHER 26 GATE 27 SCREW 2 28 JACKET ASM 29 SWITCH ASM IGNITION 30 SCREW 2 31 BOWL ASM 32 SPRING 33 BOWL 34 SHROUD 35 BEARING 36 JACKET ASM 37 SEAL DASH 38 TUBE ASM Fig 1 Typical Standard Column Key No Part Name 39 WASHER 40 SPRING 41 ADAPTER 42 RETAINER 43 BEARING 44 RING 45 SHAFT ASM 46 CLIP 47 SHAFT ASM 48 COUPLING ASM 49 BOLT 50 NUT 51 RING 52 SPRING
124. for tapered or eccentric cylinder bores Correct as necessary d Check connecting rod alignment Replace if necessary Check for excessively worn ring grooves Replace if necessary f Check for improperly assembled piston pins Replace as necessary 8 Check for insufficient ring gap clearance Correct as necessary h Inspect for engine overheating Correct as necessary i Check for sub standard fuel Correct as necessary j Check ignition timing Correct as necessary NOISY CONNECTING RODS a Check connecting rods for improper alignment and correct as necessary b Check for excessive bearing clearance and correct as necessary c Check for eccentric or out of round crankshaft journals and correct as necessary d Check for insufficient oil supply and correct as necessary e Check for low oil pressure and correct as necessary f Check for connecting rod bolts not tightened correctly and correct as necessary NOISY MAIN BEARINGS a Check low oil pressure and or insufficient oil supply and correct as necessary b Check for excessive bearing clearance and correct as necessary Check for excessive crankshaft end play and correct as necessary d Check for eccentric or out of round crankshaft journals and correct as necessary Check for sprung crankshaft and replace if necessary f Check for excessive belt tension and adjust as necessary g Check for loose torsional damper and rep
125. heat choke tube assembly is used Upon transfering components on manifold replacement operation the choke tube assembly must be removed and with a new gasket transfered to new manifold CRANKCASE FRONT COVER The installation procedure for the small V8 crankcase front cover has been revised The removal procedure as outlined on page 6 46 of the 1974 Light Truck Service Manual remains the same The revised installation procedure is as follows Installation 1 Clean gasket surface on block and crankcase front cover 2 Use a sharp knife or other suitable cutting tool to remove any excess oil pan gasket material that may be protruding at the oil pan to engine block junction 3 Apply a 1 8 bead of silicone rubber sealer part number 1051435 or equivalent to the joint formed at the oil pan and cylinder block as well as the entire oil pan front lip fig 1R 4 Apply a 1 8 bead of silicone rubber sealer part number 1051435 or equivalent to the bottom of the seal and place in position on cover 5 Loosely install cover to block NOTE Insert the four bolts loosely approximately 3 turns Install two 1 4 20 x 1 2 screws one on each side at the lower hole in the front cover Apply a bead of silicone sealer on the bottom of the seal and install on cover fig 2R Fig 1R Areas to Apply Front Cover Sealant 6 Tighten screws alternately and evenly while using drift or other suitable tool to align dowel pins in
126. hoist Catalyst Removal If necessary the catalyst in the converter can be replaced on the truck with Tool No J 25077 I 2 Install aspirator J 25077 2 Fig 5 Connect air supply line to aspirator to create a vacuum in the converter to hold beads in place when fill plug is removed Remove converter fill plug with 3 4 hex wrench or Tool J 25077 3 and 4 Fig 6 WARNING To prevent serious burns avoid contact with hot catalyst FUEL TANK AND EXHAUST SYSTEM 8 3 Fig 4 Catalytic Converter G10 Model Clamp on vibrator J 25077 1 Fig 7 5 Install empty catalyst container to converter Fig 8 Disconnect air supply to aspirator and connect air supply to vibrator Catalyst will now drain from the converter into the empty container When all the catalyst has been removed from the converter disconnect air supply to vibrator and remove container from the converter 8 Discard used catalyst Catalyst Installation Fill container with approved replacement catalyst Install fill tube extension to the fixture J 25077 1 Fig 9 3 Connect air supply to aspirator and vibrator Attach catalyst container to the fixture 5 After the catalyst stops flowing disconnect air supply to the vibrator TRUCK SUPP SERVICE 8 4 FUEL TANK AND EXHAUST SYSTEM Fig 5 Installing Aspirator Fig 6 Removing Fill Plug 6 Remove vibrator and check that catalyst has filled converter flu
127. inlet air pressure pushing on the off set choke valve and the weight of the choke linkage pulling the valve open On models heating of the thermostatic coil is accomplished by an electrically actuated ceramic resistor in an electric choke assembly On M4ME models the rear vacuum break diaphragm includes a tension bucking spring in the diaphragm plunger head to off set tension of the thermostatic coil The bucking spring assists in controlling choke valve opening through the thermostatic coil so that leaner mixtures large choke opening are maintained during warmer temperatures and richer mixtures small choke opening during colder temperatures Electric Choke Assembly Fig 43B As mentioned earlier a ceramic resistor in the electric choke assembly models is heated an electric current and the resistor warms the thermostatic coil for precise timing of choke valve opening for good engine warm up performance The electric choke operates as follows The electric choke receives an electric current operating through the engine oil pressure switch whenever the engine is running The electric current flows to a ceramic resistor that is divided into separate sections a small center section for gradual heating of TRUCK SUPP SERVICE CAM PULL OFF FEATURE VACUUM BREAK LEVER ROD INSET 1 LINK TO REAR VACUUM UNIT REAR VACUUM DIAPHRAGM THERMOSTATIC PLUNGER BUCKING SPRING L
128. inlet fitting nut and install nut in carburetor and tighten securely 6 Install fuel line and tighten connector ENGINE FUEL 6 11 W i lt al 1 d Fig 17 Fuel Filter Monojet IDLE STOP SOLENOID REPLACEMENT The idle stop solenoid should be checked to assure that it permits the throttle plate to close further when the ignition switch is turned off An inoperative solenoid should be replaced Removal 1 Remove carburetor air cleaner 2 Disconnect electrical connector at solenoid 3 Unscrew and remove idle stop solenoid Installation 1 Hold choke valve wide open so that fast idle cam follower clears fast idle cam 2 Install idle stop solenoid and turn in until it contacts lever tang 3 Connect electrical connector 4 Install air cleaner 5 Refer to Maintenance and Adjustment and adjust low and curb idle speeds CHOKE COIL REPLACEMENT Choke mechanism should be checked for free operation A binding condition may have developed from petroleum gum formation on the choke shaft or from damage Choke shaft can usually be cleaned without disassembly by using Carbon X X55 or equivalent TRUCK SUPP SERVICE 6M 12 ENGINE FUEL 1 Remove air cleaner and disconnect choke rod upper lever 2 Remove bolt attaching choke coil to head and remove choke coil and choke rod as an assembly 3 Disconnect choke rod from choke coil 4 Connect choke rod to new choke coil and install assemb
129. is not adjusted to specification or unit is defective Choke coi rod out of adjustment Choke valve and or linkage sticking or binding Idle speed setting Not enough fuel in carburetor Carburetor flooding NOTE Also check carburetor flooding when engine cranks turn over but will not start or starts hard when cold ENGINE FUEL 6M 15 ENGINE STARTS AND STALLS Check and re set the fast idle setting and fast idle cam 1 Adjust vacuum break to specification 2 If adjusted O K check the vacuum break for proper operation as follows On the externally mounted vacuum break unit connect a piece of hose to the nipple on the vacuum break unit and apply suction by mouth or use tool J 23418 to apply vacuum Plunger should move inward and hold vacuum If not replace the unit NOTE Always check the fast idle cam adjustment before adjusting vacuum break unit Adjust choke coil rod 1 Clean and align choke valve and linkage necessary Replace if 2 Re adjust if part replacement is necessary Adjust low and curb idle speeds to specifications on label in engine compartment 1 Check fuel pump pressure and volume 2 Check for partially plugged fuel inlet filter Replace if dirty 3 Remove air horn and check float adjustments as specified in carburetor overhaul section 1 Check float needle and seat for proper seal If a needle and seat tester is not available mouth suction can be applied to the needle
130. lb ft 40 lb ft 49 lb ft 90 lb ft 7 16 14 Cylinder Head 65 lb ft 80 lb ft Main Bearing Cap 65 Ib ft 70 lb ft Oil Pump 65 Ib ft Hocker Arm Stud 50 15 ft 7 16 20 Flywheel 60 lb ft 60 lb ft 65 lb ft Torsional Damper 60 lb ft 1 2 13 Cylinder Head 95 Ib ft Main Bearing Cap 110 lb ft 1 2 14 Temperature Sending Unit 20 lb ft Torsicnal Damper Oil Filter Oil Pan Drain Plug Flywheel Hand Tight 110 Ib ft 15 Ib ft Spark Plug Inside bolts on 350 engine 30 Ib ft Outer bolts Integral Head 20 Ib ft TRUCK SUPP SPECS SPECIFICATIONS 13 CARBURETOR SECTION 6M IDENTIFICATION VEHICLE ENGINE CARBURETOR K Federal California Manual Automatic Manual 7056003 17056002 ud 17056309 17056509 17056219 17056218 17056519 7045214 7045584 7045586 7045213 7045583 7045229 17056221 17056212 17056212 17056212 17056217 17056308 17056508 17056518 7045584 7045586 7045583 7045585 7045589 7045588 17056512 17056512 17056517 M C N 17056512 17056004 on CID with air conditioning CARBURETOR ADJUSTMENTS Vacuum Unloader Break M Manual Trans Cam 17056123 M 170861244
131. lower part of the instrument panel to the left of the steering column Two brake release switches are provided an electric switch disengages the regulator unit and a vacuum valve decreases the vacuum in the servo unit to quickly return the throttle to idle position The operation of each unit of the system and the operation of the entire system under various circumstances is described under Theory of Operation below THEORY OF OPERATION The purpose of the Cruise Master system 15 to allow the driver to maintain a constant highway speed without the necessity of continually applying foot pressure to the accelerator pedal Speed changes are easily made and override features allow the vehicle to be stopped slowed or accelerated as described below Engaging the Cruise System The driver accelerates to the speed at which he desires to cruise and partially depresses and releases the cruise control engagement switch button located at the end of the directional signal lever on dealer installed systems this switch will be on the instrument panel The cruise system takes over speed control and within engine limitation TRUCK SUPP SERVICE 15 2 ACCESSORIES maintains this speed regardless of changes in terrain The Engagement Switch button performs these functions 1 Above 30 mph when partially depressed and released it engages the cruise system 2 When depressed fully and held there it disengages the system 3 When r
132. missing parts interference or binding Any deficiencies should be corrected without delay by a qualified mechanic B 9 UNDERBODY In geographic areas using a heavy concentration of road salt or other corrosive materials for snow removal or road dust control flush and inspect the complete underside of the vehicle at least once each year preferably after a winter s exposure Particular attention should be given to cleaning out underbody members where dirt and other foreign materials may have collected 10 BUMPERS Check the front and rear bumper systems at 12 month 15 000 mile intervals to be sure that impact protection and clearance originally designed into these systems remain in a state of full readiness They also should be checked whenever there is obvious bumper misalignment or whenever the vehicle has been involved in a significant collision in which the bumpers were struck even when slight or no damage to the bumper systems can be seen SECTION C EMISSION CONTROL MAINTENANCE NOTE Additional recommended maintenance instructions relating to vehicle use evidence of maintenance and service replacement parts are included in the New Truck Warranty Information folder C 1 THERMOSTATICALLY CONTROLLED AIR CLEANER Inspect installation to make certain that all hoses and ducts are connected and correctly installed Also check valve for proper operation C 2 CARBURETOR CHOKE AND HOSES Check choke mechanism for proper oper
133. necessary ENGINE MISSES WHILE IDLING Check inspect and regap spark plugs Replace as necessary Remove moisture from spark plug wires and or distributor cap Check for broken or loose ignition wires Repair or replace as necessary Check condition of cylinders for uneven compression Repair as necessary Check for weak or faulty HEI system coil as outlined in Section 6Y of this manual Inspect condition of distributor cap and rotor Replace if damaged or cracked Check carburetor for internal obstructions incorrect idle speed faulty altitude compensator sticking choke or enrichment system and adjust repair or replace as necessary h Inspect carburetor fuel filter for presence of water and or impurities and correct as necessary 1 Check carburetor mounting gasket for air leaks Repair as necessary j Check distributor spark advance mechanism for proper operation Repair or replace as necessary Inspect valve train components Adjust repair and or replace as necessary Check engine for low compression Repair as necessary Check operation of exhaust gas recirculation valve Repair or replace as necessary Check ignition timing and condition of ignition system as outlined in Section 6Y of this manual Correct as necessary Check for vacuum leaks Correct as necessary Check operation of EFE valve as outlined in Section 6T of this manual Repair or replace as
134. or carburetor base gaskets as necessary 1 Remove air horn and check float adjustments as specified in carburetor overhaul section 2 excessive dirt is found in the carburetor clean the fuel system and carburetor Replace fuel filters as necessary 4 Check float needle and seat for proper seal f a needle and seat tester is not available mouth suction can be applied to the needle seat with needle installed If the needle is defective replace with a factory matched set 5 Check float for being loaded with fuel bent float hanger or binds in the float arm NOTE A solid float can be checked for fuel absorption by lightly squeezing between fingers If wetness appears surface or float feels heavy check with known good float replace the float assembly 6 Check metal float for leakage by shaking If excessive dirt is found in carburetor or idle channels clean fuel system and carburetor Replace fuel filters as necessary If mis aligned loosen screws align valves tighten screws and re stake as necessary TRUCK SUPP SERVICE Problem ENGINE FUEL 6M 49 ENGINE CRANKS TURNS OVER BUT WLL NOT START OR STARTS HARD WHEN COLD POSSIBLE CAUSE Improper starting procedure used No fuel in gas tank Choke valve not closing sufficiently when cold Choke valve or linkage binding or sticking No fuel in carburetor Engine Flooded NOTE To check for flooding remove the air cleaner with
135. or fuel tank hose on heavy duty emissions 16 If disconnected connected vacuum advance hose IDLE MIXTURE The idle mixture is factory preset and idle mixture screw is capped with a plastic limiter cap The cap permits screw to be turned about one turn leaner clockwise without breaking cap The idle mixture is set to achieve the smoothest idle while maintaining emission levels within standards prescribed by Federal Law At major carburetor overhaul the idle mixture may be adjusted Before suspecting idle mixture as cause of poor idle quality check ignition system distributor timing air cleaner PCV system evaporation emission control and compression pressures Also check all vacuum hoses and connections for leaks and check torques of carburetor attachment bolts Adjustment is made using a tachometer IDLE MIXTURE ADJUSTMENT 1 With engine at normal operating temperature air cleaner on choke open and air conditioning OFF connect a tachometer to engine 2 Set parking brake and block drive wheels 3 Disconnect carburetor and PCV hoses at vapor canister and plug on light duty emission vehicle or fuel tank hose at vapor canister on heavy duty vehicle 4 Disconnect vacuum advance hose at distributor and plug hose 5 Start engine check timing and adjust as required Reconnect vacuum advance hose 6 On engine with full vacuum advance connect vacuum advance hose otherwise leave hose disconnected and plugged 7 Po
136. purging the canister and burning the vapors in the engine Purge ports for the vapor collection canister are provided in the carburetor throttle body The ports are located slightly above the throttle valve and lead through passages to a common chamber in the throttle body to a purge tube which connects by a hose to the vapor canister The purge ports consist of a separate timed canister purge The timed bleed purge port is located in each bore next to the off idle discharge ports The timed purge operates during off idle part throttle and wide open throttle operation As the throttle valves are opened to the off idle position the purge ports are in the low pressure area and begin to remove fuel vapors from the vapor canister The purge ports are relatively large and provide adequate purge to remove all vapors collected in the canister They will bleed constantly in varying amounts during off idle part throttle and wide open throttle operation of the engine MAIN METERING SYSTEM FIG 4Q The main metering system supplies fuel to the engine from off idle to wide open throttle The two primary bores of the carburetor meter fuel through the venturi principle This design allows the use of multiple venturi for finer more stable and accurate metering control during light engine loads The main metering system is in operation at all times when air flow through the venturi is high enough to maintain efficient fuel flow from the main fuel
137. pushes the power piston up so that the ower edge of the slot in the power piston strikes the bottom side of the drive rod This moves the tapered metering rod slightly upward and out of the main metering jet allowing more fuel to flow through the jet enrichening the fuel mixture slightly ACCELERATING PUMP SYSTEM Fig 6 Extra fuel for smooth quick acceleration is supplied by a double spring loaded pump plunger Rapid opening of the throttle valve when accelerating from low speed causes an immediate increase in air flow through the carburetor bore Since fuel is heavier than air it requires a short period of time for fuel flow through the main discharge nozzle to catch up with the air flow To avoid leanness during this momentary lag in the fuel flow the accelerator pump furnishes a metered quantity of fuel which is sprayed into the air stream This mixes with the increased air flow to supply the extra fuel needed until the main discharge nozzles ENGINE FUEL 6M 5 MAIN POWER PISTON DISCHARGE NOZZLE DRIVE ROD BOOST VENTURI MAIN VENTURI PISTON SPRING MAIN METERING JET POWER PISTON ACTUATING LINKAGE THROTTLE POWER PISTON VACUUM VALVE LOWER IDLE AIR BLEED Fig 5 Enrichment System can feed the fuel required The accelerating pump is located at the side of the main fuel bowl adjacent to the venturi area It consists of a spring loaded pump plunger and pump return spring operating in a fuel we
138. rotor bearing remover and rotor assembly installer 1 25029 as shown in Figure 84 Before fully seating the assembly on front head be sure the clutch coil terminals are in the proper location in relation to compressor and that the three protrusions on the rear of the clutch coil align with the locator holes in front head Install rotor and bearing assembly retaining ring and reassemble clutch plate and hub assembly Rotate pulley rim and rotor to be sure pulley rim is rotating in line and adjust or replace as required Tighten pulley rim mounting screws to 100 inch pounds torque and lock screw heads in place TRUCK SUPP OVERHAUL J 9481 ROTOR BEARING Fig 83 Installing Clutch Rotor Bearing FRONT HEAD AND MAIN BEARING ASSEMBLY Removal 1 Remove clutch rotor and bearing assembly but do not loosen or remove pulley rim mounting screws and remove clutch rotor coil and pulley rim assembly as a total assembly 2 Remove compressor shaft seal 3 Remove the four front head mounting screws Fig 86 and remove front head assembly and discard seal ring At this point front head and bearing assembly front head seal ring Fig 87 or the Belleville and thrust washers may be replaced Installation 1 Check front head and compressor cylinder area for any dirt or lint and install a new thrust washer kit if required AIR CONDITIONING COMPRESSOR 1 33 La SPACER USE 8 PIECE OF FLAT J 25029 ROTOR A
139. seal causing 6 Replace all booster seals leakage at booster flange vent 7 Faulty booster input rod seal with 7 Replace all booster seals leakage at input rod end 8 Faulty booster cover seal with leakage 8 Replace all booster seals between housing and cover 9 Faulty booster spool plug seal 9 Replace all booster seals 10 Internal leakage in booster 10 Replace booster 11 Contamination in power steering fluid 11 Flush power steering system and replace with new fluid 12 Hydraulic lines routed incorrectly 12 Re route lines TRUCK SUPP SERVICE BRAKES 5 19 DIAGNOSIS HYDRO BOOST SYSTEM Probable Cause SLOW BRAKE PEDAL RETURN Remedy 1 Excessive seal friction in booster 1 Replace all booster seals 2 Faulty spool action 2 Clean spool and replace all booster seals 3 Broken piston return spring 3 Replace spring 4 Restriction in return line from 4 Replace line booster to pump reservoir 5 Broken spool return spring 5 Replace spring 6 Excessive pedal pivot friction 6 Lubricate pivot bushings with Delco Brake Lube 5450032 or equivalent or replace bushings GRABBY BRAKES Probable Cause Remedy 1 Broken spool return spring 1 Replace spring 2 Faulty spool action caused by 2 Inspect clean and replace all contamination in system booster seals 3 No cargo body on chassis 3 Normal condition BOOSTER CHATTERS PEDAL VIBRATES Probable Cause Remedy 1 Pow
140. servo cable as outlined in Figure 4C COLUMN MOUNTED ENGAGEMENT SWITCH Removal 1 Disconnect the battery ground cable 2 Disconnect cruise master engagement switch wiring harness plug on steering column 3 Remove plastic protector from cruise master wiring harness on column 4 Remove turn signal lever see Section 9 of this Manual 5 Connect a 15 piece of piano wire to cruise master wiring harness plug for installation before easing turn signal lever assembly up and out of the column Installation 1 Attach new engagement switch harness plug to piano wire routed through column 2 Pull connector and wire gently down column to prevent scraping wire insulation 3 Install turn signal lever see Section 9 of this Manual 4 Slide plastic wiring protector over harness and up column 5 Connect cruise master wiring harness on column 6 Connect battery ground cable DIAGNOSIS ELECTRICAL SYSTEM TROUBLESHOOTING 1 Check fuse and connector 2 Check electric brake switch as follows a Unplug connector at switch b Connect ohmmeter across cruise master contacts on brake switch The ohmmeter must indicate no continuity when the pedal is depressed and continuity when pedal is released The cruise release brake switch electric is adjusted as is the standard stop light brake switch c Replace electric brake switch if needed 3 Check clutch release switch manual transmission only same as electric relea
141. solenoid is mostly carryover from 1974 The only difference being that the terminal of the solenoid has been removed This terminal was removed because with the High Energy Ignition System there is no longer any requirement for the electrical lead from the starter solenoid to the ignition coil Refer to Section 6Y of the 1974 Overhaul Manual for all overhaul procedures TRUCK SUPP OVERHAUL SECTION 7M MANUAL TRANSMISSIONS CONTENTS OF THIS SECTION 3 Speed Tremec 56 40040 0 7M 1 4 Speed Muncie Transmission CH 465 7M 12 New Process Transfer Case Model 203 7M 15 3 SPEED TREMEC MANUAL TRANSMISSION INDEX Overhaul Operations 7M 1 Gears 7 4 Transmission Disassembly eee 7M 1 DOE MET 7M 4 Mainshaft Disassembly sese 7M 3 Synchronizer Keys and Spring 7M 4 Cleaning and Inspection 7M 3 Extension Oil Seal or Bushing 7 5 Transmission Case 15e meten 7M 3 Clutch Bearing Retainer Oil Seal 7M 6 Front and Rear 7M 3 Mainshaft Assembly sese 7M 6 Roller Bearings 7M 4 Transmission Assembly
142. the Hydro boost section of the 1974 Service Manual STOPLAMP SWITCH INSTALLATION C K Models The stoplamp switch is mounted to a flange protruding from brake pedal support bracket Installation Fig 2 1 Install the mounting clip in the brake pedal flange from the pedal side of the flange 2 Depress the brake pedal and push the switch into the clip until the shoulder on the switch bottoms on the clip Adjustment 1 Pull the brake pedal back against switch with 15 20 lbs force to properly adjust switch 2 Electrical contact should be made when the brake pedal is depressed 1 00 to 1 24 from its normally released position Fig 1 Disc Brake Rotor PARKING BRAKE Parking brake and cable replacement procedures remain the same as described in the 1974 Light Duty Truck Service Manual however cable routings clips or guides incorporate minor changes as noted in Figures 3 thru 5 PARKING BRAKE ADJUSTMENT Prestretch Requirement All Vehicles If a new parking brake cable has been installed in the vehicle it should be prestretched prior to adjustment With the equalizer installed apply the parking brake with heavy force and release three times Adjustment Foot Pedal Type NOTE Before adjusting parking brake check service brake condition and adjustment 1 Raise vehicle on a hoist 2 Loosen the equalizer adjusting nut 3 Apply the parking brake 4 notches from the fully released position 4 Tighten the eq
143. the bore with considerable force and cause personal injury 5 Using a small screwdriver remove the snap ring at the end of the master cylinder bore Then release the piston and remove the primary and secondary piston assemblies from the cylinder bore It may be necessary to plug the front outlet port and to apply low air pressure to the front compensating valve port to remove the secondary piston assembly Cleaning and Inspection Wash all parts to be re used in clean brake fluid Be sure that all foreign matter is removed from the filters in the bottom of the reservoir If the filters do not clean up they must be replaced After cleaning inspect the parts for damage and excessive wear and replace as required TRUCK SUPP SERVICE 5 12 BRAKES MOTOR HOME CHASSIS MODELS P MODELS EXCEPT MOTOR HOME Fig 8 Hydro Boost Installation Assembly 1 Lubricate the secondary piston assembly and the master cylinder bore with clean brake fluid Assemble the secondary spring shorter of the two springs in the open end of the secondary piston actuator and assemble the piston return spring longer spring on the projection at the rear of the secondary piston Insert the secondary piston assembly actuator end first into the master cylinder bore and press assembly to the bottom of the bore Lubricate the primary piston assembly with clean brake fluid Insert the primary piston assembly actuator end fir
144. the engine off and look into the carburetor bore Fuel will be dripping off nozzle and or the carburetor wil be very wet Carburetor flooding CORRECTIVE ACTION Check proper starting procedure as outlined in the owner s manual Add tuel Check fuel gauge for proper operation Adjust the choke thermostatic coil Realign the choke valve or linkage as necessary If caused by dirt and gum clean with automatic choke cleaner Do not oil choke linkage If parts are replaced check adjustments 1 Remove fuel line at carburetor Connect hose to fuel line and run into metal container Remove the high tension coil wire from center tower on distributor cap and ground Crank over engine if there is no fuel discharge from the fuel line check for kinked or bent lines Disconnect fuel line at tank and blow out with air hose reconnect line and check again for fuel dis charge f none replace fuel pump Check pump for adequate flow as outlined in service manual 2 1f fuel supply is o k check the following a Inspect fuel filter If plugged replace b If filter is o k remove air horn and check for a bind in the float mechanism or a sticking float needle If o k adjust float as specified in carburetor overhaul section Check carburetor unloading procedure Depress the accelerator to the floor and check the carburetor to determine if the choke valve is opening not adjust unloader as specified NOTE Before removing th
145. the float needle to move off its seat and more fuel to enter the float bowl This cycle continues throughout engine operation constantly maintaining a positive fuel level in the float bowl The fuel inlet filter has a retention spring located at the rear of the filter It seats between the rear of the filter and the inlet casting Should the filter become clogged from improper servicing or excess dirt in the system the retention spring will keep the filter on its seat This will stop complete stoppage of fuel flow to the carburetor until the filter can be replaced The carburetor float chamber is internally vented through a hole located in the air horn above the float chamber The purpose of the internal vent is to balance air pressure on the fuel in the float bowl with carburetor inlet air With this feature a balanced air fuel mixture ratio can be maintained during part throttle and power operation because the air pressure acting on the fuel in the float bowl will be balanced with the air flowing through the carburetor bore TRUCK SUPP SERVICE INTERNAL VENT PRESSURE RELIEF VALVE VENT HOLE FLOAT HINGE PIN FLOAT NEEDLE NEEDLE SEAT FUEL INLET FILTER FILTER RELIEF SPRING Fig 2 Float System The carburetor float chamber is externally vented by a small plastic pressure relief valve located at the top of the air horn Should excessive vapor pressure build up in the float bowl during periods of hot
146. the main fuel well where it is picked up and metered at the lower tip of the idle tube It passes up the idle tube and is mixed with air at the top ENGINE FUEL 6M 3 TOP AIR BLEED E G R EXHAUST GAS RECIRCULATION TUBE TO AIR INLET IDLE CHANNEL RESTRICTION BI METAL STRIP IDLE TUBE VALVE MAIN METERING JET HOT IDLE TIMED VACUUM COMPENSATOR PORTS FOR E G R GASKET BLEED OFF IDLE PORT Fa 1 THROTTLE VALVE 7 DLE MIXTURE NEEDLE IDLE DISCHARGE HOLE OFF IDLE OPERATION Fig 3 Idle System of the idle channel through the idle air bleed hole The air fuel mixture passes over through the cross channel and then downward through the calibrated idle channel restriction where it is further metered The mixture continues down the idle passage past the lower idle air bleed hole and off idle discharge port just above the throttle valve where it is again mixed with air The air fuel mixture then moves downward past the idle mixture needle and out through the idle discharge hole into the carburetor bore Here it mixes with the air passing around the slightly open throttle valve and then continues through the intake manifold into the engine cylinders as a combustible mixture OFF IDLE OPERATION As the throttle valve is opened from curb idle to increase engine speed additional fuel is needed to combine with the extra air entering the engine This is accomplished by the
147. thrust races and bearing may be damaged If there appears to be too much or insufficient air gap between the drive and driven plates dislocation of the shaft should be suspected If the carbon seal is not seating against the seal seat it will not be possible to completely evacuate the system as outlined under Evacuating the Refrigeration System To check for proper positioning of the axial plate on the shaft remove the clutch driven plate and measure the distance between the front head extension and the flat TRUCK SUPP OVERHAUL DISCHARGE SYSTEM BEFORE REMOVING HIGH PRESSURE RELIEF VALVE OR SUPERHEAT SUPERHEAT SWITCH Fig 23 Hi Press Relief Valve Location shoulder on the shaft as shown in Fig 21 To measure this distance use a wire gage the clearance should be between 026 and 075 If the shaft has been pushed back in the axial plate measurement greater than 075 disassemble the compressor and replace the shaft and axial plate assembly rear thrust races and thrust bearing 11 Evacuate and charge system outlined under Evacuating and Charging the Refrigeration System PRESSURE RELIEF VALVE When necessary to replace the pressure relief valve located in the compressor rear head casting the valve assembly should be removed after PURGING THE SYSTEM OF REFRIGERANT and a new valve and gasket installed The entire system should then be Evacuated and Recharged Fig 23 INTERNAL MECHANISM
148. tighten all bolts to specified 1 Raise and support vehicle on hoist Drain transfer case forques NOTE Before connecting prop shafts to companion 2 Disconnect speedometer cable back up lamp and TCS 2 flanges be sure locknuts torqued to specifications switch TRUCK SUPP SERVICE 7M 4 CLUTCH AND MANUAL TRANSMISSIONS NOTE install Boot NOTE No insulation prior to installation of to be installed under Nut amp Knob retainer to be installed under NOTE With trans case in Retainer 2 wheel Hi position align indicator plate to center of NOTE With trans case in Aim shift lever Neutral position align Indicator Plate to center of Shift Lever NOTE Do not lubricate bolt threads only shank groove MODEL 203 MODEL 205 Fig 2Q Transfer Case Controls TRUCK SUPP SERVICE SECTION 7A AUTOMATIC TRANSMISSION CONTENTS OF THIS SECTION Turbo Hydra Matic 350 Transmission Turbo Hydra Matic 400 475 Transmission TURBO HYDRA MATIC 350 TRANSMISSION INDEX General Description uite eerie rie res 7 1 Manual Shaft Range Selector Inner Lever Vacuum Modulator Assembly TA 1 and Parking Linkage Assemblies 7A 3 Maintenance and Adjustments TA 2 Service Operations
149. to meet the particular requirements of the engine transmission and vehicle and although they may look alike they are not always interchangeable Refer to carburetor part number and or specifications This section divided into sub sections by carburetor model covers the repair procedures for the various carburetors assembly and disassembly procedures and internal carburetor adjustment Although illustrations showing bench operations are used most single operations when not part of a general overhaul should be performed if practical with the carburetor on the engine Typical illustrations and procedures are used except where specific illustrations or procedures are necessary to clarify the operation Refer to 1974 Overhaul Manual for overhaul procedures on the Rochester 4MV carburetor Refer to Light Duty Truck Service Section for external carburetor adjustment procedures ROCHESTER 1MV CARBURETOR INDEX Disassembly 5 essei rief Hee ayasa irre re ei 6M 1 Cleaning and Inspection n 6M 4 Assembly S e eco ia eese x DO t Ce o dre i RIDE OLOR IR TE 6M 4 Special TOO ettet pate petens 6M 20 DISASSEMBLY Air Horn Removal 1 Remove auxiliary vacuum break diaphragm assembly from air horn by removing two attaching screws Remove auxiliary vacuum break diaphragm plunger from vacuum diaphragm link which is permanently attached to the choke lever The lever and link asse
150. to prevent excessive adjustment in the field However the carburetor has a limited idle mixture adjustment If it is necessary to remove the idle mixture needles for cleaning purposes or if they are defective the following procedure should be used Using a pair of side cutter pliers clip off the limit tang on the limiter cap Then unscrew the idle mixture screw and spring from throttle body If new idle mixture needles are installed no plastic limiter caps are required If the original idle mixture needles had to be removed install the idle mixture needle and springs into throttle body as described under Assembly No further disassembly of the throttle body is necessary CHOKE HOUSING BAFFLE PLATE Fig 8C Carburetor Choke INTERMEDIATE CHOKE LEVER Fig 9C Choke Housing CAUTION No attempt should be made to remove the throttle valves or shaft as it may be impossible to reassemble the throttle valves correctly in relation to the idle discharge orifices CLEANING AND INSPECTION Dirt gum water or carbon contamination in or on exterior moving parts of the carburetor are often responsible for unsatisfactory performance For this reason efficient carburetion depends upon careful cleaning and inspection while servicing 1 Thoroughly clean carburetor casting and metal parts in an approved carburetor cleaning solution Example X 55 or equivalent CAUTION Any rubber parts plastic parts diaphragm as
151. up Again depress and release the primary piston several times 4 Assemble the diaphragm and cover on the master cylinder NOTE The master cylinder is ready for installation on the vehicle Normal bleeding procedures should be followed after the master cylinder 15 installed m M DIAPHRAGM FILTER RESERVOIR COMPENSATING VALVE SEAL VALVE POPPET SPRING SECONDARY SPRING SECONDARY PISTON PISTON RETURN SPRING PRIMARY PISTON SNAP RING Fig 13 Mini Master Cylinder Exploded View TRUCK SUPP SERVICE _ _ BRAKES 5 17 Fig 14 Master Cylinder Released Position TRUCK SUPP SERVICE 5 18 BRAKES DIAGNOSIS HYDRO BOOST SYSTEM NOTE Before cheching the hydraulic power booster for the source of trouble refer to the trouble diagnosis procedures for Standard Brahes After these possible causes have been eliminated check for the probable cause and remedy as outlined below Normal Operating Characteristics Brake pedal application of the Hydro boost system differs in some respects from a vacuum type power brake system in the following manner 1 On pedal application until booster run out 3 On the first full application of the brake pedal slight power steering pump noise may be a slight hissing sound may be heard The hiss heard is the accumulator charging and the noise should go away in
152. upper control arm rubber bumper then follow same procedure as above Reinstall bumper when alignment procedure is completed K SERIES TRUCK FRONT WHEEL BEARINGS AND SPINDLE BEARINGS Whenever front wheel bearings are lubricated the spindle needle bearings should also be lubricated with the same chassis grease Under normal conditions the lubrication interval should be 12 000 miles off road use such as in mud or water will require shorter intervals Figure 1 shows the bearings The spindle bearings are accessible after removing the spindle shown in figure 2 Refer to page 3 44 of the 1974 Light Truck Service Manual for details SPINDLE Fig 1 Hub Cross Section TRUCK SUPP SERVICE 3 2 FRONT SUSPENSION Fig 2 Removing Spindle FRONT AXLE BALL JOINT ADJUSTMENT The ball joint adjustment procedure found on page 3 39 of the 1974 Light Truck Service Manual should be modified in step 3 to read 3 Apply a fish scale to the tie rod mounting hole of the steering knuckle arm With the knuckle assembly in the straight ahead position determine the right angle pull required to keep the knuckle assembly turning after initial break away This pull should not exceed 33 165 for each knuckle assembly in either direction NOTE SCALE READING SHOULD NOT EXCEED 33 LBS FOR EITHER KNUCKLE IN EITHER DIRECTION Fig 3 Determining Front Axle Ball Joint Adjustment TRUCK SUPP SERVICE SECTION 4 REAR SUSP
153. way 4 Manually hold air valve closed 5 Turn tension adjusting screw clockwise specified number of turns after spring contacts pin 6 Holding adjusting screw tighten lockscrew and replace air valve dashpot rod and front vacuum break diaphragm unit and bracket 2 WITH LOCK SCREW LOOSENED AND 7 WITH AIR VALVE CLOSED TURN ADJUSTING SCREW SPECIFIED NUMBER OF TURNS AFTER SPRING CONTACTS PIN 3 TIGHTEN Lock SCREW TENSION ADJUSTING SCREW Fig 57 Air Valve Spring Wind Up Adjustment TRUCK SUPP SERVICE 6M 46 ENGINE FUEL 3 WITH PLUNGER HELD INWARD TURN PLUNGER SCREW IN OR OUT TO OBTAIN SPECIFIED DECELR PM l ne 2 WITH ENGINE AT SPECIFIED IDLE SPEED PUSH IN ON END OF PLUNGER UNTIL SEATED 1 ADJUST IDLE SPEED 7 SCREW TO OBTAIN SPECIFIED R P M VACUUM OPERATED DECELERATION CONTROL Fig 58 Throttle Lever Actuator Adjustment THROTTLE LEVER ACTUATOR ADJUSTMENT Fig 58 1 Disconnect valve to actuator hose at valve and connect to an external vacuum source equipped with a vacuum gauge 2 Check the throttle lever shaft and linkage to be sure that they operate freely without binding or sticking 3 Start engine and run until warmed up and idle is stable Place transmission in neutral or park 4 Apply 20 in Hg vacuum to the actuator Manually open the throttle slightly and allow to close against the extended actuator plunger Note the engine RPM 5 If the RPM noted above is n
154. which could permit exhaust fumes to seep into the passenger compartment Any defects should be corrected immediately To help continue integrity exhaust system pipes and resonators rearward of the muffler must be replaced whenever a new muffler is installed B 4 SUSPENSION AND STEERING Check for damaged loose or missing parts or parts showing visible signs of excessive wear or lack of lubrication in front and rear suspension and steering system Questionable parts noted should be replaced by a qualified mechanic without delay B 5 BRAKES AND POWER STEERING Check lines and hoses for proper attachment leaks cracks chafing deterioration etc Any questionable parts noted should be replaced or repaired immediately When abrasion or wear is evident on lines or hoses the cause must be corrected B 6 ENGINE DRIVE BELTS Check belts driving fan AIR pump generator power steering pump and air conditioning compressor for cracks fraying wear and tension Adjust or replace as necessary B 7 DRUM BRAKES AND PARKING BRAKE Check drum brake linings and other internal brake components at each wheel drums wheel cylinders etc Parking brake adjustment also should be checked whenever drum brake linings are checked NOTE More frequent brake checks should be made if driving conditions and habits result in frequent brake application GENERAL INFORMATION AND LUBRICATION 0 15 B 8 THROTTLE LINKAGE Check for damaged or
155. with the groove entering the pin holes last Tap pin with a hammer until flush with cast surface of valve body b Models CJ and CL Install 1 2 accumulator valve stem end out into bore Place bore plug into valve bore and install grooved retaining pin from cast surface side of the valve body with the groove entering the pin holes last Tap pin with a hammer until flush with cast surface c Models CT and CZ Install the 1 2 accumulator valve stem end out and 1 2 accumulator secondary spring Install the bore plug and compress spring until grooved retaining pin can be inserted from the cast surface side of the valve body Install retaining pin with the grooved end entering the pin hole last and tap in place until flush with cast surface of the valve body In next bore up install detent spring and spacer Compress spring and secure with small screwdriver fig 10B Install detent regulator valve wide land first 6 Install detent valve narrow land first 10 Install bore plug hole out depress spring by pressing in on plug install retaining pin and remove screwdriver In lower right hand bore install 3 2 valve Install 3 2 spring spacer bore plug hole out and retaining pin In next bore up install the 2 3 shift valve open end out into the bore and install 3 2 intermediate spring TRUCK SUPP OVERHAUL MODELS amp CK l6 cox MODELS C amp CL
156. 0 104 C amp G 10 3 Spd Trans L 6 250 LD4 C amp K 10 All Trans L 6 292 L25 C K G amp 20 30 All Trans L 6 292 L25 C amp P 10 20 30 G 20 30 K 20 Manual Trans C 10 20 30 G 20 30 P 10 20 K 20 Auto Trans V 8 350 2BBL LF5 Auto Trans Man Trans V 8 350 4BBL LS9 V 8 350 4BBL LS9 DISTRIBUTOR no Pg Bl CE d CENTRIFUGAL ADVANCE 0 1200 12 2000 22 4200 0 1200 12 0 2000 22 4200 0 1100 12 1600 16 2400 VACUUM ADVANCE 0 4 Hg 18 12 Hg 0 4 Hg 15 2 12 Hg O 4 Hg 15 12 Hg 0 4 Hg 24 15 Hg 0 10 Hg 10 13 Hg 0 10 Hg 10 13 Hg 0 4 Hg 18 12 Hg 0 6 Hg 15 12 Hg 18 12 Hg INITIAL SPARK PLUG TIMING amp GAP TRUCK SUPP SPECS DISTRIBUTOR Continued MODEL NO APPLICATION 1112884 V 8 350 4BBL EMISS CLASS io wo CENTRIFUGAL VACUUM ADVANCE ADVANCE 1150 O 8 Hg 10 13 Hg 22 SPECIFICATIONS 19 INITIAL SPARK PLUG PE amp GAP TIMING 2 BTC R44TX V 8 350 4BBL LS9 LS9 v 8 400 4BBL LF4 1112940 1112941 1112886 V 8 400 4BBL LF4 V 8 454 4BBL Federal LF8 C 10 P U w Cat Converter V 8 454 4BBL LF8 C 10 P U w o Cat Converter Federal 1112494
157. 000 miles more often under dusty driving conditions FUEL FILTER Replace filter element located in carburetor inlet every 12 months or 15 000 miles whichever occurs first or if an in line filter is also used every 30 000 miles Replace in line filter every 30 000 miles GOVERNOR The attaching bolts should be kept tight the optionally available governor should be kept clean externally and the filter element should be replaced every 15 000 miles ACCELERATOR LINKAGE Lubricate with engine oil every 30 000 miles as follows 1 On V8 engine lubricate the ball stud at the carburetor lever 2 On L6 engine lubricate the two ball studs at the carburetor lever and lubricate the lever mounting stud Do not lubricate the accelerator cable x PJ I Qun us di d m e M Mr Pp mnn 12 Yvmssas XM AUTOMATIC TRANSMISSION FLUID RECOMMENDATION Use automatic transmission fluids identified with the mark DEXRON 72 Il Check the fluid level at each engine oil change period Automatic transmissions are frequently overfilled because the fluid level is checked when the fluid is cold and the dipstick indicates fluid should be added However the low reading is normal since the level will rise as the fluid temperature increases A level change of over 3 4 inch will occur as fluid temperature rises from 60 F to 180 F Overfilling can cause foaming and loss of fluid throug
158. 17056508 120 325 015 7 8 325 2NL 17056509 M 19 32 120 325 015 7 8 325 1NL 120 325 7 8 275 INDEX 17056517 A 7 16 9 32 325 015 7 8 1705651 8 5 16 9 32 120 325 7 8 325 2NL 015 7 8 Needle Seat with Groove at upper edge 5 16 Needle Seat without Groove at upper edge 7 16 MAME Carburetor 17056228 7 16 9732 120 300 160 ze 325 nner Pump Rod Location IDLE SPECIFICATIONS SHOWN IN RPM LIGHT DUTY EMISSION REQUIREMENTS CURB FAST IDLE IDLE IDLE MIXTURE IDLE AUTO FED 425DR 550DR 2100N 575 550DR EMU FED 425N 900 2100 1075 900N 12F1U CAL 425DR 630 600DR 12F1U 1000N 2100N 1150 1000N 12F1U CAL 425N 650 600DR 1202 FED 600DR FED 800N 12J2 ENGINE DISPLACE TRANS USAGE LOW BASE 1600N 650 600DR FED 800N 1600N 900 800N 650 600DR 600DR 1600N 650 600DR 12J4B 12J4B 12 34 12 14 12840 TRUCK SUPP SPECS SPECIFICATIONS 16 HEAVY DUTY EMISSION REQUIREMENTS FED 450 600 2400N 600N 600N zoov 1600N 800 700 GM113 AUTO Fc zooN 770 700 GM113 nem 250 99 i CAL With vacuum advance hose connected and EGR hose disconnected and plugged 1400 rpm for throttle return control system with vacuum appl
159. 1976 steering linkage are identical with those outlined in the 1974 Light Duty Truck Service Manual Section 9 Figure 4 shows the latest linkage used on the G Series truck and the P Series Motor Home models IDLER ARM Use of the proper diagnosis and checking procedure is essential to prevent needless replacement of good idler arms The proper checking procedure is as follows 1 Raise the vehicle in such a manner as to allow the front wheels to rotate freely and the steering mechanism freedom to turn Position the wheels in a straight ahead position 2 Using a push pull type spring scale located as near the relay rod end of the idler arm as possible exert a 25 lb force upward and then downward while noticing the total distance the end of the arm moves This distance should not exceed 1 8 inch Figure 3A It is necessary to ensure that the correct load is applied to the arm since it will move more when higher loads are applied It is also necessary that a scale or ruler be rested against the frame and used to determine the amount of movement since observers tend to over estimate the actual movement when a scale is not used The idler arm should always be replaced if it fails this test NOTE Jerking the right front wheel and tire assembly back and forth thus causing an up and down movement in the idler arm is not an acceptable method of checking since there is no control on the amount of force being applied TRUCK SUPP SERV
160. 3 1 002 All Others 0035 Crankshaft End Play 002 006 006 010 Diameter 1 999 1 2000 2 099 2 100 2 199 2 200 2 1985 2 1995 Production 0003 Max EDS Service 001 Max Production 0002 Max Service 001 Max Production 0007 0027 0013 0035 0009 0025 Rod Bearing Clearance Service 0035 Max Rod Side Clearance 0006 0017 008 014 013 023 CAMSHAFT Ite Intake 2217 2315 2600 2343 Lift 0027 Exhaust 2217 2315 2733 2343 Journal Diameter 1 8682 1 8692 1 9482 1 9492 Camshaft Runout 0015 Max Camshaft End Play 001 005 In Line Engine mm VALVE SYSTEM Lifter Hydraulic ES Rocker Arm Ratio 1 75 1 1 50 1 1 70 1 24 Valve Lash One Turn Down From Zero Lash Face Angle Int amp Exch 45 Seat Angle Int amp Exh 46 Seat Runout Int amp Exh 002 Max Seat Width take 1 32 1 16 Exhaust Produc Int iion Exh Service 0010 0015 0032 0010 Hi Limit Production 001 Intake 002 Exhaust Exhaust 1 91 Inlet 2 03 76 84 1 61 76 84 1 70 183 195 1 20 194 206 1 25 Stem Clearance 0012 0029 2 12 74 86 1 88 288 312 1 38 190 Free Length Pressure Closed Ibs
161. 35 MPH The engine should be off and the transmission in neutral However the rear wheels must be raised off the ground or the drive shaft disconnected when the transmission is not operating properly or when a speed of 35 MPH or distance of 50 miles will be exceeded CAUTION J a truck is towed on its front wheels only the steering wheel must be secured with the wheels in a straight ahead position Four Wheel Drive Trucks It is recommended that the truck be towed with the front wheels off the ground The truck can be towed however with the rear wheels off the ground if there is damage in the rear wheel area In this event the transmission selector lever should be placed in the N neutral position and with conventional four wheel drive the front drive disengaged With Full Time four wheel drive the transfer case should be in high Towing speeds should not exceed 35 MPH for distances up to 50 miles If truck is towed on its front wheels the steering wheel should be secured to keep the front wheels in a straight ahead position When towing the vehicle at slow speeds approx 20 MPH for a very short distance only the transmission must be in NEUTRAL and with conventional four wheel drive the transfer case MUST be in TWO WHEEL HIGH With Full Time four wheel drive the transfer case should be in high When towing the vehicle at faster speeds for greater distances the following steps MUST be taken e If front wheels are on th
162. 370 5 and 1 21370 6 to transmission case with attaching screws checking to make certain the gauge pin does not bind in servo pin hole fig 4B b Apply 25 ft Ib torque and select proper pin to be used during assembly of transmission Selecting proper length pin is equivalent to adjusting band The band lug end of each selective apply pin bears identification in the form of one two or three rings If both steps of J 21370 5 are below the gauge surface the long pin identified by 3 rings should be used d If the gauge surface is between the steps the medium pin identified by 2 rings should be used If both steps are above the gauge surface the short pin identified by ring should be used m NOTE If the transmission is in the vehicle be careful when the detent solenoid is removed as it prevents the spacer plate and gasket and check balls from dropping down 5 Remove detent solenoid attaching screws detent solenoid and gasket 6 Withdraw electrical connector and ring seal 7 Remove control valve assembly spacer plate and gasket 8 Remove six 6 check balls from cored passages in transmission case NOTE Mark location of balls for aid in reassembly 9 Remove front servo piston retainer ring washer pin spring retainer and spring from transmission case OIL PUMP AND INTERNAL CASE COMPONENTS Removal Delete
163. 4F Rear View of Transfer Case NOTE If necessary to replace rear bearing support cover and press bearing from cover Position new bearing to outside face of cover and press bearing into cover with a 06 overhang From lower side of case remove pry output shaft front bearing Disengage front output shaft from chain and remove shaft from transfer case Remove bolts attaching intermediate chain housing to range box Lift or using a chain hoist remove intermediate housing from range box Remove chain from intermediate housing Remove lockout clutch drive gear and input shaft assembly from range box NOTE A 1 1 2 to 2 hose clamp may be installed on end of the input shaft to prevent loosing the roller bearings 123 which may fall out of clutch assembly if it is pulled off the input shaft MANUAL TRANSMISSION 7M 19 20 Pull up on shift rail and disconnect rail from link 21 Remove lift input shaft assembly from range box NOTE At this point the transfer case is completely disassembled into its subassemblies Each of these subassemblies should then be disassembled for cleaning and inspection REAR OUTPUT SHAFT HOUSING REAR ASSEMBLY Disassembly 1 Remove speedometer driven gear from rear section of rear output housing 2 Pry old seal out of bore using a screwdriver or other suitable tool 3 Using a screwdriver pry behind open ends of snap ring and remove snap ring retaining rear bearing in housing Fig
164. 5 in 165 35 in Ibs 35 in Ibs 35 in Ibs 25 in Ibs asin ibs inms 35in Ibs 35 in Ibs 35 in Ibs 35 in 165 35 in Ibs 60 in Ibs 60 in Ibs 60 in Ibs 60 in Ibs 60 Ibs EU 120in lbs 120in lbs 2 ftis 20ft ibs 238 Ibs 120 in Ibs 120 in 165 17 ft Ibs 98 in 165 98 in Ibs 35 Ibs 35 in Ibs 35 in Ibs 35 in Ibs E 20 in Ibs 30 in 165 20 in 16 25 in 165 43 in 165 30 ft Ibs 30 ft Ibs 30 ft Ibs 75 ft Ibs 70 in 165 70 in Ibs e 48 ft bs 20 ft Ibs 18 ft Ibs 20 ft Ibs 18 ft Ibs 110 ft Ibs 65 ft Ibs 65 ft Ibs 65 ft Ibs 30 ft Ibs Steering Gear Support Reinforcement Bolts TRUCK SUPP SPECS SPECIFICATIONS 24 TORQUE SPECIFICATIONS Component C10 30 G10 30 K10 20 P10 30 Tie Rod End Stud Nuts 45 ft Ibs 45ftibs 45 ft Ibs Pitman Shaft Nut 185 ft Ibs 185 ft Ibs 185 ft Ibs Idler Arm to Frame Bolts 30 ft Ibs 30 ft Ibs 30 ft Ibs Idler Arm to Relay Rod Stud Nut 60 ft Ibs 70 ft Ibs 60 ft Ibs Pitman Arm to Relay Rod Nut 60 ft Ibs 70 ft Ibs 60 ft Ibs Pitman Arm to Idler Support Arm Nut S usi 50 f bs Steering Connecting Rod Clamp Nuts 40 ft Ibs Tie Rod Clamp B
165. 7 Ignition spark timing 8 Spark plugs 9 Secure intake manifold 10 Engine temperature Use the following tables to diagnose carburetor Problem Idle speed setting Manifold vacuum hoses disconnected or improperly in stalled Carburetor loose on intake manifold Intake manifold is loose or gaskets are defective Hot idle compensator not operating where used Carburetor flooding NOTE Also check carburetor flooding when engine cranks turn over but will not start or starts hard when cold ENGINE IDLES ROUGH AND STALLS Re set low and curb idle speeds under maintenance and adjustments Check all vacuum hoses leading into the manifold or carburetor base for leaks or being disconnected Install or replace as necessary Torque carburetor to manifold bolts 10 14 ft lbs Using a pressure oil can spray light oil or kerosene around manifold legs and carburetor If engine RPM changes tighten or replace the manifold gaskets or carburetor base gaskets as necessary Normally the hot idle compensator should be closed when engine is running cold and open when engine is hot approx 140 F at replace if defective 1 Remove air horn and check float adjustment as specified in carburetor overhaul section 2 Check float needle and seat for proper seal If a needle and seat tester is not available mouth suction can be applied to the needle seat with needle installed If the needle is defecti
166. 70 2780 TUBELESS TIRES MOUNTED ON 15 TAPERED BEAD SEAT DROP CENTER RIMS 8 17 5 D 1640 1790 1940 2075 2205 2335 2455 8 19 5 D 2110 gt 2270 2410 2540 2680 2800 WIDE BASE TUBELESS TIRES USED AS SINGLES Tire Load Limits at Various Inflation Pressures Tire Tire Load Limits at Various Inflation Pressures Size 45 55 55 60 65 70 75 C78 15LT 1370 H78 15LT 1830 8 00 16 5 1730 8 00 16 5 1730 1840 1945 2045 8 00 16 5 1730 1840 1945 2045 2145 2240 2330 8 75 16 5 1990 8 75 16 5 1990 2110 2240 2350 8 75 16 5 1990 2110 2240 2350 2470 2570 2680 9 50 16 5 2350 2500 2650 2780 9 50 16 5 2350 2500 2650 2780 2920 3050 3170 10 16 5 2330 10 16 5 2330 2480 2620 2750 TIRES USED AS DUALS Load Tire Load Limits at Various Inflation Pressures Size Range so i as 45 E 550 557 L 60 3 265 70 75 TUBE TIRES MOUNTED 5 TAPERED BEAD SEAT RIMS 1420 1580 1580 1685 1780 1815 1815 1930 8 17 5 D 1445 1575 1700 1820 1935 2050 2155 8 19 5 D 1850 1990 2110 2230 2350 2460 8 19 5 1850 1990 2110 2230 2350 2460 2570 2680 Refer to Tire Load and Inflation Pressure Notes 4 2780 Ibs at 80 Ibs pressure TRUCK SUPP SERVICE WHEELS AND TIRES 10 3 TIRE LOAD AND INFLATION PRESSURE TIRES FOR LIGHT TRUCKS USED IN HIGHWAY SERVICE Cont d WIDE BASE TUBELESS TIRES USED AS
167. ALL amp UPPER EDGE OF CHOKE VALVE sear REAR VACUUM RODIN BREAK DIAPHRAGM USING OUTSIDE VACUUM SOURCE OFSLOT PLUNGER _ BUCKING SPRING M P d PUSH UP ON CHOKE COIL LEVER DIAPHRAGM PLUNGER PULLED OUT UNTIL SEATED BUCKING nop TO Be SPRING COMPRESSED ADJUST PLACE CAM FOLLOWER LEVER ON HIGHEST STEP OF FAST IDLE CAM Fig 50 Rear Vacuum Break Adjustment 4 Push up on the choke coil lever inside choke housing toward closed choke until stem is pulled out and seated bucking spring compressed 5 With choke rod in bottom of slot in choke lever gauge between upper edge of choke valve and air horn wall Dimension should be as specified 6 Bend vacuum break rod at point shown if necessary to adjust 7 After adjustment install vacuum hose to vacuum break unit 8 Install thermostatic cover and coil referring to automatic choke coil adjustment AUTOMATIC CHOKE COIL ADJUSTMENT Hot Air Fig 51 1 Install choke thermostatic coil and cover assembly with gasket between choke cover and choke housing NOTE Tang on thermostatic coil must be inserted in slot of choke coil lever pick up arm small block V8 or on 454 V8 make sure tang contacts bottom of side ENGINE FUEL 6M 43 3 ALIGN INDEX 2 ROTATE COVER AND COIL ASSEMBLY COUNTERCLOCKWISE UNTIL VALVE JUST CLOSES ARKS AS SPECIFIED e PLACE CAM FOLLOWE
168. ARBURETOR SPECIAL TOOLS J 8328 CARBURETOR HOLDING TOOL J 9789 01 UNIVERSAL CARBURETOR Set of 4 GAUGE SET s VT d J 25322 PUMP LEVER PIN DRIVE PUNCH J 23417 CHOKE LEVER J 5197 BENDING TOOL INSTALLING TOOL Fig 1ST Special Tools TRUCK SUPP OVERHAUL SECTION 6Y ENGINE ELECTRICAL NOTE Except for the following changes all information listed in Section 6Y of the 1974 Light Duty Truck Overhaul Manual is applicable to 1976 light duty trucks Refer to 1974 Overhaul Manual for any overhaul procedure not contained herein STARTING MOTOR The 1976 starter is mostly carryover from 1974 The only difference being that the terminal of the starter solenoid has been removed This terminal was removed because with the High Energy Ignition System there is no longer any requirement for the electrical lead from the starter solenoid to the ignition coil Refer to Section 6Y of the 1974 Overhaul Manual for all overhaul procedures 10 SI SERIES 100 TYPE GENERATOR The 1976 10 SI generator is mostly carryover from 1974 The only difference being that a 40 ohm resistor has been added to the warning and indicator circuit see Section 6Y in service section of this manual The purpose of this resistor is to provide a definite warning indicator light in the case of an open field circuit in the generator Refer to Section 6Y of the 1974 Overhaul Manual for all overhaul procedures STARTING SOLENOID 1976 starter
169. ARIES ACCORDING TO TRUCK MODEL Fig 2 C K P Truck Frame Reference Points TRUCK SUPP SERVICE FRAME 2 3 Fig 3 G Van Truck Frame Reference Dimensions TRUCK SUPP SERVICE SECTION 3 FRONT SUSPENSION GENERAL INFORMATION Front suspension design and geometry are basically similar to 1974 Except for the items listed on these pages all information in Section 3 of the 1974 Light Truck Service Manual is applicable to 1976 Light Trucks Refer to the Specifications section of this manual for complete torque values capacities tolerances alignment data etc MAINTENANCE AND ADJUSTMENTS ALIGNMENT NOTE ALL SERIES Front end alignment directions are given beginning on page 3 13 of the 1974 Light Truck Service Manual It is good practice to set front end values to specifications while the vehicle is in its normally loaded condition Trucks which are consistently operated under heavy load conditions should have toe in adjusted with the truck under heavy load This procedure should result in longer tire life CAMBER AND CASTER ADJUSTMENT REMOVAL OF SHIM PACKS G10 30 C10 30 The following procedures should assist in alignment G10 20 Models C10 Models with 3 4 Nut With vehicle on front end rack jack at frame and raise the wheel off the ground This will allow the upper control arm to drop down far enough to use a socket on the nuts and permit shim removal G30 Models C20 and 30 Models with 7 8 Nut Remove the
170. After installing the switch press the switch plunger as far forward as possible This presets the switch for adjustment The switch will then adjust itself with the first idle open throttle application of the accelerator pedal REAR SEAL Removal 1 Remove propeller shaft 2 Pry seal out with screw driver Installation All Models Except CL 1 Use a non hardening sealer on outside of seal body and using Tool J 21359 drive seal in place TRUCK SUPP SERVICE 7 6 AUTOMATIC TRANSMISSION PLUNGER 2 Re install propeller shaft PLUNGER SAU Model CL TRANSMISSION i i 1 CONTROL 1 Use a non hardening sealer on outside of seal body and SWITCH N using Tool J 24057 drive seal in place MI 2 Re install propeller shaft TRANSMISSION REPLACEMENT The procedure for transmission replacement remains the same with the addition of this note NOTE If necessary the catalytic converter may have to be disconnected to provide adequate clearance for transmission removal This procedure will include removal of the converter support bracket CK SERIES 32 SERIES Fig 1L Detent Downshift Switch TRUCK SUPP SERVICE SECTION 8 FUEL TANK AND EXHAUST SYSTEM CONTENTS OF THIS SECTION FUEL TANK Refer to the 1974 Light Duty Truck Service Manual for servicing of the fuel tank and evaporation control system with the following exception COMPONENT PART REPLACEMENT 3 Disconnect gauge unit fuel line and w
171. BEND ROD TO ADJUST Fig 11 Fast Idle Cam Adjustment 5 If adjustment is required bend rod 6 Connect rod to choke valve PRIMARY VACUUM BREAK ADJUSTMENT Fig 14 1 Place cam follower on highest step of fast idle cam 2 Plug purge bleed hole with masking tape over vacuum break end cover 3 Using an outside vacuum source apply vacuum to primary vacuum break diaphragm until plunger is fully 3 BOTTOM OF ROD SHOULD BE EVEN WITH TOP OF LEVER na 3 p 1 CHOKE VALVE COMPLETELY BEND ROD TO ADJUST 2 NOTE TO ADJUST REMOVE RETAINING CLIP AND UPPER END OF CHOKE COIL ROD RECONNECT AFTER ADJUSTMENT ON ROD TO END OF TRAVEL ROD SHOULD BE AGAINST STOP IN HOUSING INSTALL RETAINING CLIP Fig 12 Choke Coil Rod Adjustment Lt Duty Emissions ENGINE FUEL 6M 9 gt CHOKE VALVE COMPLETELY f CLOSED O PUSH DOWN ON ROD TO STOP END OF TRAVEL TOP OF ROD SHOULD BE EVEN WITH BOTTOM OF HOLE NOTE TO ADJUST REMOVE RETAINING CLIP AND UPPER END OF CHOKE COIL ROD RECONNECT AFTER ADJUSTMENT a INSTALL RETAINING CLIP 4 BEND ROD TO ADJUST Fig 12A Choke Coil Rod Adjustment Heavy Duty Emissions seated 4 Push up on choke coil lever rod in end of slot 5 Insert specified gauge between upper edge of choke valve and air horn wall 6 If adjustment is required bend vacuum break rod 7 After adjustment make sure there is no interference or binding and rem
172. Band Apply Pin All Models Except of output shaft for models CA 11 29 64 below end of output shaft for models CG and CR using J 5590 fig 6B CONTROL VALVE Fig 5B Removing Steel Speedometer Drive Gear 2 Remove manual valve from upper bore 3 Install Special Tools J 22269 J 24675 on Disassembly a accumulator piston and remove retaining ring fig 8B 1 Position control valve assembly with cored face up and accumulator pocket nearest operator ccumulator Piston TRUCK SUPP OVERHAUL 7 6 AUTOMATIC TRANSMISSION SPEEDOMETER Fig 8B Installing Steel Speedometer Drive Gear 4 Remove front accumulator piston and spring fig 9B 5 On the right side adjacent to the manual valve remove the 1 2 valve train as follows a All models except CJ and CP remove the retaining pin 1 2 modulator bushing 1 2 regulator valve 1 2 regulator spring 1 2 detent valve and 1 2 shift valve b Models CJ and CP remove the retaining pin 1 2 modulator bushing 1 2 modulator spring 1 2 modulator valve and 1 2 shift valve 6 From next bore down remove retaining pin 2 3 shift valve spring 2 3 modulator valve bushing 2 3 modulator valve 3 2 intermediate spring and 2 3 shift valve 7 From next bore down remove retaining pin bore plug spring spacer and 3 2 valve 8 At other end of assembly top bore remove retaining pin and bore plug detent valve detent regulator valve spring and sp
173. C for air cleaner used on G truck with 350 400 V8 engine Refer to figure 16C for air cleaner used with 454 V8 engine Refer to figure 17C for air cleaner used of P20 42 P30 42 and P30 32 truck with 350 V8 engine and 4MV carburetor Inspection Visual 1 Check for proper secure connections of heat pipe and hoses 2 Check for kinked or deteriorated hoses Repair or replace as required Fig 11C Cleaning Polywrap Band TRUCK SUPP SERVICE GASKET POSITION RED SURFACE DOWN EXTENSION GASKET POSITION RED SURFACE DOWN A S U gt B viai 2 B ROUTE HOSE OUTBOARD OF FUEL LINE Fig 12C Air Cleaner L6 Intergrated Head Operational 1 Remove air cleaner cover and install temperature gauge Tool J 22973 as close as possible to sensor fig 18C Reinstall cover without wing nut Temperature must be below 85 F before proceeding With the engine Off observe damper door position through snorkel opening Snorkel passage should be open fig 68 view A If not check for binds in linkage Start and idle engine With air temperature below 85 F snorkel passage should be closed fig 9C view B When damper door begins to open snorkel passage remove air cleaner cover and observe thermometer reading It should be between 85 F and 115 F If damper door does not close completely or does not open at correct temperature continue with th
174. CCELERATOR PEDAL CHECK VOLTAGE READING REPLACE VOLTAGE REGULATOR REPLACE ROTOR AND VOLTAGE REGULATOR REPLACE VOLTAGE REGULATOR READING IS 12 5 to 15 5 READING PERFORM IS NOT NEXT TWO 12 5 to 15 5 STEPS 4 amp 5 GO TO STEP 5 GO TO STEP5 GO TO STEP 5 TRUCK SUPP SERVICE SECTION 7M CLUTCHES AND MANUAL TRANSMISSIONS CONTENTS OF THIS SECTION CLUTCH CONTROLS GENERAL DESCRIPTION The clutch operating controls for G models fig the cross shaft When the pedal is depressed the pedal pull a mechanical type consisting of a pendant type pedal return rod moves rotating the cross shaft pushing the clutch fork spring pedal pull rod cross shaft fork push rod clutch fork rod rearward and pivoting the clutch fork This action moves and throwout bearing The pedal pull rod is routed vertically the throwout bearing against the clutch release fingers from the clutch pedal lever down through the toe panel to releasing the clutch TRUCK SUPP SERVICE 7M 2 CLUTCH AND MANUAL TRANSMISSIONS V 8 ENGINE L 6 ENGINE Fig 1T Clutch Linkage Assembly G Models TRUCK SUPP SERVICE CLUTCH AND MANUAL TRANSMISSIONS 7M 3 MANUAL TRANSMISSIONS SERVICE OPERATIONS The service procedures for the Tremec 3 speed will be the 3 Remove skid plate and crossmember supports as same as 3 speed listed in the 1974 Service Manual necessary 4 Disconnect rear prop shaft from transfer ca
175. CK SUPP SERVICE 1i Disconnect vacuum lines and electrical connectors Remove heater distributor duct assembly 12 Transfer duct and relays 13 To reassemble Reverse Seps 1 12 HEATER CORE CASE AND CORE G MODEL Replacement Follow Steps 1 10 of Heater Air Distributor and Extension Duct Replacement procedure 11 Remove battery 12 Disconnect heater hoses at heater core drain pan below hoses refill radiator upon completion 13 Remove air inlet valve assembly 14 Remove temperature door control cable at heater case 15 Remove heater assembly 16 Remove heater core Reseal heater case AIR INLET VALVE G MODEL Replacement Follow Steps 1 10 of Heater Air Distributor and Extension Duct Extension Duct Replacement procedure 11 Remove duct assembly Disconnect vacuum hose 12 Remove vacuum valve 13 To reassemble Reverse Steps 1 12 TEMPERATURE DOOR CABLE G MODEL Replacement Follow Steps 1 10 of Heater Air Distributor and Extension Duct Replacement procedure HEATER AND AIR CONDITIONING 14 9 Fig 10 Expansion Tube CK Model 11 Disconnect temperature door control cable at heater case 12 Disconnect temperature door control cable at control 13 Make up new cable 14 To reassemble Reverse Steps 1 13 EXPANSION TUBE CK MODEL FIG 10 new type expansion tube is incorporated into the air conditioning systems of 1976 CK series trucks Removal Fig 11 1 Purge the syst
176. Check power piston for free up and down movement 14 power piston is sticking check power piston and cavity for dirt or scores Check power piston spring for distortion Clean or replace as necessary Power system not operating Metering rod not adjusted to specification Adjust metering rod per carburetor overhaul section Float level too low 1 Check and reset float level to specification per carburetor overhal section Float not dropping far enough into float bowl Check for binding float hanger and for proper float align ment in float bowl Main metering jet or metering rod dirty pluaged or incorrect 1 If the main metering jets are plugged or dirty and exces part sive dirt is in the fuel bowl Carburetor should be com pletely disassembled and cleaned 2 Check the jet or rod for being the correct part Consult the parts list for proper usage The last two digits stamped on the jet face are the same as the last two digits of the part number Air valves binding stuck closed or wide open Free up air valve shaft and align air valves 2 Torque air horn screws evenly using proper tightening sequence 3 Check air valve spring for closing tension If defective replace with spring Problem ENGINE STARTS HARD WHEN HOT Choke valve not opening completely 1 Check for binding choke valve and or linkage Clean and free up or replace parts as necessary Do not oil choke linkage 2 Check and
177. D DOWN LEFT SIDE Fig 2 C 10 03 w F44 C 10 06 amp 18 and K 10 L 6 LD4 Engine Wiring CYLINDER ASM c FWD LP HARN TEMPERATURE SWITCH NOTE INSTALL GENERATOR LEAD POINTING B INBOARD SO THAT CONDUIT WILL NOT LEFT SIDE INTERFERE WITH THERMAC HEAT TUBE RIGHT SIDE Fig 3 C K 10 thru 30 Truck V 8 LF4 LG9 LS9 Engine Wiring TRUCK SUPP SERVICE DISTRIBUTOR ASM m REAR LP HARN OIL PRESS SW OIL PRESS SW VIEW A VIEW B LEFT SIDE PARKING BRAKE CABLE SPEEDO CABLE NOTE ROUTE HARN REARWARD OF PUMP BRACE NOTE PRESS BOOT TERMINAL WITH SMALL END DOWN VIEW amp 253 LEFT SIDE ENGINE ELECTRICAL 6Y 3 iac D GENERATOR m FWD NOTE PRESS BOOT OVER TERMINAL WITH SMALL END UP TO FUEL METER 7 f 1 45 AN PURPLE NOTE THIS CONNECTION MUST BE POSITIONED AS SHOWN VIEW D COOLANT RECOVERY TANK VIEW B HEATER BLOWER OIL SENDER ASM amp 253 RIGHT SIDE Fig 5 G 10 thru 30 Truck 1 6 LD4 Engine Wiring TRUCK SUPP SERVICE 6 4 ENGINE ELECTRICAL CARB SOL y tum A Z 248 BULKHEAD CONN lt fe quis SO N PARKING BRAKE CABLE gt SPEEDO CABLE L TEMP SWITCH FWD VIEW NOTE PRESS BOOT OVER TERMINAL WITH SMALL END DOWN DASH PANEL 4 e 517 VIEW LEFT SIDE VIEW C TEMP SWITCH 7777 2 MODULATOR PIPE 7A LEF
178. DUALS Tire Load Tire Load Limits at Various Inflation Pressures Tire Load and Inflation Pressure Notes 1 The cold tire inflation pressure rating applies to the tire pressure when the vehicle has not been driven for three hours or more or driven less than one mile 2 It is normal for tire pressures to increase 4 8 PSI or more when the tires become hot from driving Do not bleed or reduce tire inflation pressures after driving your vehicle Bleeding serves to reduce cold inflation pressure and increase tire flexing which can result in tire damage and failure 3 For sustained driving over 75 mph with passenger car type tires or when using passenger car type snow tires cold inflation pressures should be increased 4 PSI above the recommended cold inflation pressures in the Tire Wheel Load and inflation Pressure Chart for the load being carried up to a maximum of 32 PSI for load range B tires 36 PSI for load range C and 40 PSI for load range D Sustained speeds above 75 mph are not recommended when the 4 PSI adjust ment exceeds the maximum pressures stated above 4 For sustained driving over 65 mph with truck type tires or when using truck type snow tires cold inflation pressures should be increased 10 PSI above those specified in the Tire Wheel Load and Inflation Pressure charts for the load being carried Where the 10 PSI pres sure increase is limited by the maximum whe l capacity shown in the Wheel Code and Limits Ch
179. E PLASTIC MAIN METERING MAIN WELL JET INSERT METERING ORIFICE PART THROTTLE ADJUSTMENT SCREW MAIN VENTURI THROTTLE MAIN WELL VALVE Fig 23 Main Metering System through the main well air bleeds is mixed with fuel through calibrated holes in the main well tube The mixture moves up and out of the main discharge nozzles into a mixture high speed passage where more air is added The mixture then travels down through the mixture passage to the small venturi where it is delivered to the air stream and on into the engine intake manifold On some models an additional fuel circuit called pull over enrichment P O E has been provided which supplements the main metering system of the carburetor unit In order to provide sufficient enrichment to the main metering system at higher air flows two additional fuel feeds are located in the air horn just above the choke valve They connect directly to the fuel in the float bowl through channels which lead directly into a tube that extends into the fuel just above the main metering jets At approximately 8 pounds of air per minute and above the extra fuel enrichment is added to supplement the main metering system With the addition of the pull over enrichment system leaner mixtures can be maintained during the part throttle or cruising ranges and extra fuel supplied at higher air flows to meet engine demands POWER ENRICHMENT SYSTEM Fig 24 The conventional
180. EARING AGAINST HUB THRUST BEARING Fig 51 Installing 1st A 6 Piston Assembly Into Front Cyiinder Half REAR THRUST RACES AND BEARING BALL AND SHOE FRONT AND REAR FRONT THRUST RACES AND BEARINGS Fig 52 Installing 2nd A 6 Piston complete drawing the cylinder halves together 9 Generously lubricate all moving parts with clean 525 viscosity refrigerant oil and check for free rotation of the parts 10 Replace the suction cross over cover Fig 56 Compress the cover as shown to start it into the slot and then press or carefully tap it in until flush on both ends AIR CONDITIONING COMPRESSOR 1 21 O Ring Discharge Crossover Tube Bushing Fig 53 Service Type A 6 Discharge Cross Over Tube Discharge Crossover Tube Fig 54 Installing Discharge Crossover Tube PISTONS IN STAIR STEP POSITION 3 l REAR THRUST ji Va RACES AND BEARING Fig 55 A 6 Pistons Positioned in Stair Step Arrangement TRUCK SUPP OVERHAUL 1 22 AIR CONDITIONING COMPRESSOR Fig 56 Installing Suction Cross over Cover A 6 COMPRESSOR INTERNAL MECHANISM Re Install 1 Place internal mechanism on Internal Assembly Support Block J 21352 with rear end of shaft in block hole Now install new O ring and bushing on front end of discharge cross over tube Fig 57 The O ring and bushing are Service parts only for internal mechanisms that have been disassembled in the field see Fig 53
181. ED MUNCIE Clutch Gear Retainer to Case Bolts Side Cover to Case Bolts Extension to Case Bolts Shaft Lever to Shifter Shaft Bolts Lubrication Filler Plugs Transmission Case to Clutch Housing Bolts Crossmember to Frame Nuts Crossmember to Mount Bolts Transmission Drain Plug 2 3 Cross Over Shaft Bracket Retaining Nut 18 ft 1 Rev Swivel Attaching Bolt Mount to Transmission Bolt Rear Bearing Retainer Cover Bolts Filler Plug Drain Plug Clutch Gear Bearing Retainer Bolts Universal Joint Front Flange Nut Power Take Off Cover Bolts Parking Brake Countergear Front Cover Screws Rr Mainshaft Lock Nut 4 Whl Drive Mdls 100 ft Transmission To Clutch Housing Bolts Crossmember to Mount Mount to Transmission THREE SPEED TREMEC Clutch Gear Retainer to Case Bolts Top Cover to Case Bolts Extension to Case Bolts Shift Lever to Shifter Shaft Bolts Lubrication Filler Plug sssaaCn m s n ar Transmission Case to Clutch Housing Bolts 75 ft Crossmember to Frame Nuts 25 ft Crossmember to Mount Bolts 40 ft 2 3 Cross Over Shaft Bracket Retaining Nut 18 ft 1 Rev Swivel Attaching Bolt Mount to Transmission Bolt Idler Shaft Lock 200 ft lbs Idler Shaft Cover Bolts 18 ft Ibs Front Output Shaft Front Bearing Retainer 6 30 ft Ibs Front Output Shaft Yoke Lock Nut 200 ft lbs Rear Output Shaft Bearing Retainer Bolts 30 ft
182. EL JUMPER TEST LIGHT OFF CHECK LAMP BULB CONNECT SHORT TESTER TO LAMP CIRCUIT YELLOW AT JUNCTION OF YELLOW AND BLACK WIRES POINT AND TO BODY GROUND REPAIR YELLOW WIRE REMINDER LIGHT BUZZER NEVER ON 1 CHECK FUSE 2 CHECK INSTRUMENT PANEL JUMPER GROUND TEST LIGHT OFF CONNECT SHORT TESTER TO TIMER FEED CIRCUIT TIMER REPAIR PINK WIRE CONNECTOR AND TO BODY GROUND TEST LIGHT OFF REPLACE TIMER TEST LIGHT ON WITH SHORT TESTER CHECK CONTINUITY BETWEEN GROUND TERMINAL AND BOOY GROUND TEST LIGHT OFF REPAIR GROUND CONNECTION CHECK LIGHT AND WHEN DIAGNOSING A WARNING SYSTEM FAILURE AND SYSTEM AUTOMATICALLY SHUTS OFF BECAUSE OF THE 4 8 SECOND A MINIMUM OF 3 MINUTES BE ALLOWED BETWEEN THE DIAGNOSTIC STEPS TO ALLOW THE TIMER TO RESET IKEY IN OFF POSITION DURING THIS PERIOD LIGHT AND BUZZER ON CONTINOUSLY BUCKLING BELT WILL TU TEST LIGHT ON AN OFF B THE PINK AND BLACK WIRE TEST LIGHT ON CONN REPAIR BLACK WIRE REPLACE TIMER VECTOR CONNECT SHORT TESTER BETWEEN REPAIR BLACK WIRE REMINDER LIGHT NORMAL BU ER NEV DISCONNECT HARNE BUCKLE SWITCH AT ON 85 TO DRIVER JUNCTION INSTRUMENT PANEL JUMPE TEST LIGHT ON TURN IGNITION CONNECT SHORT TESTER TO OUTPUT CIRCUIT BHOWN AND YELLOW WIRESI AND 10 BODY GROUND BUZZER INOPERATIVE CHECK BUZZER BY APPLYING 12 VOLT POWER SOURCE
183. EMATIC Fig 3i High Energy Ignition Basic Wiring module which determines from RPM when to start current building in the primary windings of the ignition coil Each time the timer core teeth align with the pole piece teeth the pick up coil magnetic field is changed creating a different voltage The pick up coil sends this different voltage signal the electronic module which electronically shuts off the ignition coil primary circuit This in turn collapses the coil magnetic field induces high secondary voltage and fires one spark plug The electronic module delivers full battery voltage to the ignition coil which is limited to five to six amperes There is no primary resistance wire in the HEI system The electronic module triggers the closing and opening of the primary circuit instantaneously with no energy lost due to breaker point arcing or capacitor charging time lag The capacitor in the HEI unit functions only as a radio noise suppressor This instantaneous and efficient circuit triggering enables the HEI system to deliver up to approximately 35 000 volts through the secondary wiring to the spark plugs Because of the higher voltage the HEI system has larger diameter 8 millimeter spark plug wires with silicone insulation The silicone wire is orange in color more heat resistant than standard black wire and less vulnerable to deterioration Silicone insulation is soft however and must not be mishandled TRUCK SUPP SERV
184. EMS AND OR COULD RESULT IN MAJOR REPAIR EXPENSE IT MUST BE REPLACED WITH ONE OF THE SAME PART NUMBER OR WITH AN EQUIVALENT PART IF REPLACEMENT BECOMES NECESSARY DO NOT USE A REPLACEMENT PART OF LESSER QUALITY OR SUBSTITUTE DESIGN TORQUE VALUES MUST BE USED AS SPECIFIED DURING REASSEMBL Y TO ASSURE PROPER RETENTION OF THIS PART CONTENTS OF THIS SECTION Brake System Identification sss 5 1 Standard Brakes epe 5 5 Vacuum Power Brakes 5 e eret irt a D 5 10 Hydro boost 0 6000 5 10 BRAKE SYSTEM IDENTIFICATION The following charts are included as a guide in determining and their basic differences The remaining charts outline vehicle brake system The first chart describes brake systems system to vehicle application BRAKE SYSTEM DESCRIPTION SYSTEM JB1 JB3 JB5 JB6 JB7 JB8 JB9 FRONT BRAKES Disc 11 86 x 1 28 Disc 11 86 x 1 28 Disc 11 86 x 1 28 Disc 12 50 x 1 28 Disc 12 50 x 1 28 Disc 12 50 x 1 53 Disc 14 25 x 1 53 REAR BRAKES Drum 11 00 x 2 00 Drum 11 00 x 2 00 Drum 11 00 x 2 75 Drum 11 15 x 2 75 Drum 13 00 x 2 50 Drum 13 00 x 3 50 Drum 15 00 x 4 00 BRAKE ASSIST None Manual Brakes Vacuum Single Diaphragm Vacuum Dual Diaphragm Vacuum Dual Diaphragm Vacuum Dual Diaphragm Hydraulic Hydroboost Hydraulic Hydroboost TRUCK SUPP SERVICE
185. ENGAGES WITH AUDIBLE THUNK PARK START ENGINE AND SWITCH HALF WAY WITH CAR IN DEPRESS ENGAGE CHECK BROWN WHITE FOLLOWING METHODS STRIPE WIRE BY EITHER THE 1 FOR OMMMETER SYSTEM CHECKOUT CHECK REFER TO ELECTRICAL WITH IGNITION BATTERY VOLTAGE AT BROWN WHITE WIRE CONNECTOR VOLTMETER THE TERMINAL AT MUST READ DISCONNECTED REGULATOR Fior REPLACE ARE OK REGULATOR VACUUM REMOVE ENGINE MANIFOLD VACUUM SUPPL Y HOSE AT REGULATOR CHECK FOR VACUUM AT HOSE vacuum NO VACUUM CHECK VACUUM SUPPLY HOSE VACUUM FITTING AT ENGINE REPLACE REGULATOR Fig NO THUNK IS HEAR CHECK FUSE AND BRAKE SWITCH ADJUSTMENT CHECK GROUND WIRE FROM REGULATOR ON A CAR ISEE ELECTRICAL SYSTEM CHECKOUT CHECK REGULATOR CIRCUIT BLADE TERMINAL AND GROUND BETWEEN HOLD IT SHOULO READ 46 5 CHECK ENGAGEMENT CHECKOUT SWITCH SEE ELECTRICAL SYSTEM CHECK WHITE WIRE AT REGULATOR ASSEMBLY FOR BATTERY VOLTAGE 12 VOLTS WITH ENGAGEMENT SWITCH DEPRESSED HALF WAY IGNITION SWITCH ON IF ALL ABOVE CONDITIONS ARE AND NO REPLACE REGULATOR THUNK I5 HEARD ENGINE DOES NOT ACCELERATE DISCONNECT ORIFICE TUBE HOSE AT REGULATOR AND PLUG IT ENGINE RUNNING ENGAGE SWITCH DEPRESSED HALF WAY ENGINE DOES NOT ACCELERATE VACUUM LEAK RESTRICTION 15 INDICATED DISCONNECT LARGE HOSE CONNECTED TO THE REGULATOR AND CHECK FOR VACUUM REGULATOR FITTING IENGAGE SWITCH DEPRESSED HALF WAY
186. ENSION PROPSHAFT AND AXLE GENERAL INFORMATION Rear suspension design is basically similar to 1974 The axle chart figure 1 shows the application of specific axles to the various truck models Except for the items on the following pages all information n Section 4 of the 1974 Light Truck Service Manual is applicable to 1976 Light Trucks MAINTENANCE ITEM K MODEL CV JOINT LUBRICATION while Propshaft CV joints can be lubricated on the vehicle with the use of J 25512 1 and adaptor J 25512 2 Access to the joint is limited and can best be accomplished by the following procedure Figure 2 shows how the joint conceals the lube fitting A when it is in the downward position and how it opens B when the fitting is in the upward position Access to the lube fitting can only be gained from above the opened joint This require a flex hose that can bend between the propshaft and the underbody Install the rigid needle tip J 25512 2 on the end of the flexhose Use the tip to depress the ball into the lube fitting then pump grease into the fitting as shown in figure 3 ECCE e o roe m 0 semen e gt oe m gt Except C20 Crew Chevrolet Salisbury 5700 10 1 2 Cab C20 Crew Cab Salisbury 7500 10 1 2 Wheel Chevrolet Camper Dual C30 Wheel Dana Salisbury 7500 10 1 2 Camper ith rn G30 Wheel Salisbury 6200 9 3
187. ER TYPE TIRES FOR LIGHT TRUCKS USED IN HIGHWAY SERVICE Tire Range Tire Load Limits at Various Inflation Pressures Ld o 22 2 3o s2 3a 3 4 1 L k cc RHET 78 15 970 1030 1080 1130 1180 1230 1270 78 15 1060 1110 1160 1220 1270 1320 1370 678 15 B 1140 1190 1260 1310 1370 1420 1470 G78 15 D 1140 1190 1260 1310 1370 1420 1470 1530 1570 1620 1670 GR78 15 B 1140 1190 1260 1310 1370 1420 1470 H78 15 B 1240 1310 1370 1440 1500 1560 1610 H78 15 D 1240 1310 1370 1440 1500 1560 1610 1670 1720 1770 1830 178 15 1300 1370 1440 1500 1570 1630 1690 JR7B 15 B 1300 1370 1440 1500 1570 1630 1690 L78 15 B 1380 1460 1530 1590 1670 1730 1790 LR78 15 C 1380 1460 1530 1590 1670 1730 1790 1860 1910 L78 15 C 1380 1460 1530 1590 1670 1730 1790 1860 1910 L78 15 D 1380 1460 1530 1590 1670 1730 1790 1860 1910 1970 2030 8 25 15 D l 1140 1190 1260 1310 1370 1420 1470 1530 1570 1620 1670 TIRES FOR LIGHT TRUCKS USED IN HIGHWAY SERVICE TIRES USED AS SINGLES Tire Load Tire Load Limits at Various Inflation Pressures Size Range 30 35 40 45 59 55 66 65 60 75 TUBE TYPE TIRES MOUNTED ON 5 TAPERED BEAD SEAT RIMS 6 50 16 C 1270 1390 1500 1610 7 00 15 C 1350 1480 1610 1720 7 00 15 D 1350 1480 1610 1720 1830 1940 2040 7 00 16 C 1430 1560 1680 1800 7 50 16 C 1620 1770 1930 2060 7 50 16 1620 1770 1930 2060 2190 2310 2440 7 50 16 1620 1770 1930 2060 2190 2310 2410 2560 26
188. ERATOR PEDAL Check for correct opening and closing positions by operating accelerator pedal and if any binding is present check routing Refer to figures 5C through 8C for removal and installation of accelerator pedal INNER SPRING QUI R SPRING OUTER NOTE With Inner Spring inside INNER SPRING Spring anchor both Springs thru nylon bushing in Carb Lever and hole in Carb Bracket T RETAINER CAUTION Cable is not SEALER to be kinked or damaged in Be any woy during assembly y DA operation gt CARB LEVER CABLE FASTENER RETAINER Fig 1C Accelerator Controls L6 Light Duty Emissions Fig 2C Accelerate Controls L6 Heavy Duty Emissions CAUTION Flexible components hoses wires conduits etc must not be routed within 2 inches of moving parts of accelerator linkage forward of Support unless routing is positively controlled ENGINE SUPPORT CABLE ASSEMBLY NOTE Cable is not to be kinked or damaged in any way during assembly Dt SPRING OUTER ios SPRING INNER NOTE With Inner Spring inside Outer Spring anchor both Springs thru hole in Carburetor Lever and holes in Support and Bracket e Fig 3C Accelerator Controls V8 2Bbl TRUCK SUPP SERVICE 6M 66 ENGINE FUEL CAUTION Flexible components hoses wires conduits etc must not be routed within 2 inches of moving parts of accelerator linkage forward of Support unless rout
189. ERVICE 6Y 18 ENGINE ELECTRICAL HIGH ENERGY IGNITION SYSTEM 1 6 engines SEQUENCE RESULT CONNECT oo OHMMETER READS ABOVE 1 OHM SCALE REPLACE DISCONNECT ke A READS 0 TO 1 OHM CONNECTOR f X1 SCALE READS 6 000 TO 30 000 OHMS READS MORE THAN 30 000 REPLACE OHMS OR LESS THAN COIL 6 000 OHMS CONNECT lt p A f OHMMETER NAA J STARTS e LESS c dor l THAN INFINITY REPLACE COIL O NO START READS INFINITE X 1000 SCALE 521655 e THAN INFINITY REPLACE COIL x 1000 SCALE IPICK UP REMOVE GREEN amp WHITE LEADS FROM MODULE CONNECT OHMMETER FROM CONNECT OHMMETER REPEAT STEPS 8 AND 9 ACROSS 2 LEADS WHILE MOVING READS 500 TO SCREWET 1500 OHMS E ADING IS STILL OK n on DOES NOT READ 500 1500 0HMs REPLACE COIL PICK UP IF NOT OK CHECK MODULE i WITH TESTER REMOVE AND REPLACE MODULE TRUCK SUPP SERVICE ENGINE ELECTRICAL 6Y 19 HIGH ENERGY IGNITION SYSTEM L 6 engines GH CU RESULT PLUGS amp PLUG WIRES REPAIR OR y REPLACE Je I Z2 4 2 lt CHECK SPARK A UGH REMOVE CAP ASSY VISUALLY INSPECT FOR MOISTURE DUST NECESSARY CRACKS BURNS ETC OFF n RUNS ROUGH CONNECT READS 6 000 TO OHMMETER 30 000 OHMS READS MORE THAN 30 000 REPLACE OHMS OR LESS THAN
190. ERVICE ENGINE ELECTRICAL 6Y 25 SEQUENCE RESULT REPAIR GENERATOR CLUSTER CONNECTOR f 0 BULKHEAD FUSE BLOCK CONNECTOR SEQUENCE RESULT 2 REPAIR SHORT BETWEEN LIGHT ON NO 1 BROWN WIRE DISCONNECT M GENERATOR LIGHT OFF PROBLEM generator light ON ignition OFF AND NO 2 RED WIRE REPLACE RECTIFIER BRIDGE TRUCK SUPP SERVICE 6Y 26 ENGINE ELECTRICAL Chart 4 BATTERY PROBLEM battery UNDERCHARGED GENERATOR BELT 8 CARBURETOR GENERATOR 1 F SEQUENCE DISCONNECT CONNECT TEST LIGHT BETWEEN REPLACE IF NECESSARY ADJUST TENSION TO 80 LBS GENERATOR BELT 2 POST CONNECT JUMPER TERMINAL AND GROUND RECONNECT NEGATIVE CABLE 4 CHECK VOLTAGE ACROSS POST WHILE CRANKING 5 REPLACE BATTERY TAP CABLE AGAINST TEST LIGHT 1 DISCONNECT FEED WIRE IF READING IS WITHIN 5 VOLT OF VOLTAGE AT GEN IF READING IS NOT WITHIN 5 VOLT OF READING AT GEN CHECK FOR BATTERY CABLE AND STARTER TO DELCOTRON CIRCUIT RESISTANCE CABLE amp BATTERY TRACE amp CORRECT CONTINUOUS DRAIN ON BATTERY CONNECT VOLTMETER TERMINAL AND GROUND CRANK ENGINE LONG ENOUGH FOR STABILIZED READING TEST BATTERY USING BATTERY LOAD TEST PROCEDURE RESULT GO TO STEP 2 TEST LIGHT ON TEST LIGHT OFF NO DRAIN ON BATTERY GO TO STEP 3 D NEEDLE ABOVE 9 0 V
191. Equal 1 Average 2 and 4 Readings Equal 1 Average Also if one area is regularly used to aim headlamps the floor slope adjustment procedures can be eliminated by using tape or paint to indicate on the floor the center line for the rear wheel of all vehicles Then check the floor level for several vehicles with varying wheelbase measurements Indicate on the floor a front wheel center line for each wheelbase along with the plus or minus reading for that position Thereafter each time the headlamps are aimed merely place the rear wheels of the vehicle on the rear wheel center line and transfer the plus or minus reading of the front wheel center line to the floor slope dial of the aiming unit 7 Remove floor slope adapters from each unit and attach a headlamp adapter fig 5 as determined by type of headlamps on the vehicle There is an adapter for all standard size and shape sealed beam units LEVEL VIAL USED ONLY FOR CALIBRATION Fig 2 Floor Slope Adapter J 25300 6 H pest steps hino Yat otker die 8 Position aimer with headlamp adapter attached so that the three guide points of the lamp are in contact with NOTE Unless the floor is abnormally sloped it is not the three steel inserts inside the headlamp adapter necessary to obtain floor slope readings for both sides Secure aimer to headlamp by pushing locking handle of the vehicle If for some reason floor is abnormally fig 3 forward to engage rubber suction cap an
192. Fixture J 9396 in a vise and clamp the compressor in the Holding Fixture 2 Keep clutch hub from turning with Clutch Hub Holder J 25030 or J 9403 and remove locknut from end of shaft using Thin Wall Socket J 9399 Fig 3 CAUTION 7o avoid internal damage to the compressor DO NOT DRIVE OR POUND on the Clutch Plate and Hub assembly OR on the end of the shaft If proper tools to remove and replace clutch 4 parts are not used it is possible to disturb the position of the axial plate keyed to the ma n shaft resulting in compressor damage seal leakage due to shifting of the crankshaft 3 Thread Clutch Plate and Hub assembly Remover J 9401 6 into hub Hold body of Remover with a wrench and tighten center screw to remove Clutch Plate and Hub assembly Fig 4 Fig 3 Removing Shaft Lock Nut Remove square drive key from shaft or drive plate hub Remove hub spacer retainer ring using Snap Ring Pliers J 5403 21 and then remove hub spacer Fig 5 Inspect driven plate for cracks or stresses in the drive surface Do not replace driven plate for a scoring condition Fig 6 TRUCK SUPP OVERHAUL 1 4 AIR CONDITIONING COMPRESSOR 4 as CLUTCH PLATE AND HUB ASSEMBLY REMOVER J 9401 CLUTCH PLATE AND HUB ASSEMBLY SNAP RING PLIERS 21 J 5403 2 RETAINER RING Fig 5 Removing or Installing Retainer Ring in A 6 Clutch Drive Plate If the frictional surface shows signs o
193. GINE FUEL FIXED IDLE AIR BY PASS IDLE CHANNEL RESTRICTION IDLE TUBE LOWER IDLE AIR BLEED TIMED BLEED CANISTER PURGE CALIFORNIA ONLY fi OFF IDLE METERING PORT JET IDLE LIMITER gt IDLE THROTTLE DISCHARGE VALVE PURGE TUBE HOLE CANISTER Fig 3Q Idle System extend down into the well After passing up the idle tube the fuel is mixed with air at the top of each tube through an idle air bleed The fuel mixture then crosses over to the idle down channels where it passes through a calibrated idle channel restriction It then passes down the idle channel past the lower idle air bleed holes and off idle discharge ports just above the throttle valves where it is mixed with more air The air fuel mixture then moves down to the idle needle discharge holes where it enters the carburetor bores and mixes with air passing the slightly open throttle valves The venturi system is very sensitive to air flow and on applications where large amounts of idle air are needed to maintain higher idle speeds the fixed idle air by pass system is used This consists of air channels which lead from the top of each carburetor bore in the air horn to a point below each primary throttle valve At normal idle extra air passes through these channels supplementing the air passing by the slightly opened throttle valves The purpose of the idle air by pass system is to allow reduction in the amount of air going past
194. Hand Side of Cylinder Block at Rear of Distributor e 8 Cylinder Engine Unit Number Located on Pad at Front Right Hand Side of Cylinder Block GENERAL INFORMATION AND LUBRICATION 0 3 Delcotrons Delcotron Unit Serial Number Located at Top of Rear Housing Batteries Battery Code Number Located on Cell Cover Top of Battery Starters Starter Serial Number and Production Date Stamped on Outer Case Toward Rear SERVICE PARTS IDENTIFICATION NES V LN VEHICLE IDENTIFICATION NUMBER NOTE THE SPECIAL EQUIPMENT LISTED BELOW BEEN INSTALLED ON THIS VEHICLE FOR PROPER IDENTIFICATION OF REPLACEMENT PARTS SURE TO SPECIFY THE APPLICABLE OPTION NUMBERS OPTION DESCRIPTION DESCRIPTION IMPORTANT RETAIN THIS PLATE AS A PERMANENT RECORD Fig 3 Service Parts Identification Plate SERVICE PARTS IDENTIFICATION PLATE The Service Parts Identification Plate fig 3 is provided on all Truck models On most series it will be located on the inside of the glove box door or on Forward Control series it will be located on an inner body panel The plate lists the vehicle serial number wheelbase and all Production options or Special Equipment on the vehicle when it was shipped from the factory including paint information ALWAYS REFER TO THIS INFORMATION WHEN ORDERING PARTS KEYS AND LOCKS Two keys are provided with each vehicle Different lock cylinders operated by a separate key are available as an opt
195. ICE 6Y 12 ENGINE ELECTRICAL SERVICE OPERATIONS Routine Maintenance The HEI system is designed to be free from routine maintenance If component part replacement should become necessary however several items specific to the HEI system should be noted Electronic Module The electronic module is serviced by complete replacement only When replacing the module a liberal coating of special silicone grease MUST be applied to the metal mounting surface on which the module will be installed If this grease is not applied the module will not cool properly which can cause the module to malfunction A tube of this special silicone grease is supplied with each replacement module Spark Plug Wires Figs 4i bi The 8 millimeter silicone insulation spark plug wire boots seal more tightly to the spark plugs Twist the boot about a half turn in either direction to break the seal before pulling on the boot to remove the wire WARNING Do Not remove spark plug wires with the engine running The higher secondary voltage is capable of jumping an arc of greater distance and could cause an electric shock Fig 4i 8 Cylinder HEI Ignition Wiring Timing Light Connections Timing light connections should be made in parallel using an adapter at the distributor number one terminal CYL NO 6 5 CYL NO 4 CYLNO 3 CYL NO 2 CYL NO 1 DISTRIBUTOR C Fig 5i 6 Cylinder HEI Ignition Wiring Tachometer Connections In the d
196. ICE 9 4 STEERING Fig 3A Checking Idler Movement Caution should be used in assuming shimmy complaints are caused by loose idler arms Before suspecting suspension or steering components technicians should eliminate shimmy excitation factors such as dynamic imbalance run out or force variation of wheel and tire assemblies and road surface irregularities TIE RODS Service procedures for the 1976 tie rod assemblies are identical to those outlined in the 1974 Light Duty Truck Service Manual Section 9 Figure 5 shows the updated tie rod clamp relationships for 1976 models POWER STEERING PUMP Figs 6 12 Removal 1 Disconnect hoses at pump When hoses disconnected secure ends in raised position to prevent drainage of oil Cap or tape the ends of the hoses to prevent entrance of dirt On models with remote reservoir disconnect reservoir hose at pump and secure in raised position Cap hose pump fittings 2 Install two caps at hose fittings to prevent drainage of oil from pump 3 Loosen bracket to pump mounting nuts 4 Remove pump belt 5 Remove pump from attaching parts and remove pump from vehicle Installation 1 Position pump assembly on vehicle Fig 6 and install attaching parts loosely 2 Connect and tighten hose fittings 3 Fill reservoir Bleed pump by turning pulley backward counter clockwise as viewed from the front until air bubbles cease to appear 4 Install pump belt over p
197. ING COMPRESSOR 1 5 DRIVE PLATE SCORING OF DRIVE AND DRIVEN PLATES IS NORMAL DO NOT REPLACE FOR THIS CONDITION Fig 6 Clutch Driven Plate and Drive Plate KEY KEYWAY IN SHAFT Xs HOLDING FIXTURE J 9396 Fig 7 Aligning Drive Plate Key Replace 1 If original pulley and bearing assembly is to be reinstalled wipe frictional surface of pulley clean If frictional surface of pulley shows any indication of damage due to overheating the pulley and bearing should be replaced 2 Check bearing for brinelling excessive looseness noise and lubricant leakage If any of these conditions exist bearing should be replaced See Compressor Pulley Bearing Replacement Procedure 3 Press or tap pulley and bearing assembly on neck of compressor until it seats using Pulley and Bearing Installer J 9481 with Universal Handle J 8092 Fig 12 The Installer will apply force to inner race of bearing DRIVE PLATE INSTALLER J 9480 01 Fig 8 Installing Drive Plate and prevent damage to bearing Check pulley for binding or roughness Pulley should rotate freely Install retainer ring using Snap Ring Pliers J 6435 26 Install absorbent sleeve in compressor neck Install absorbent sleeve retainer in neck of compressor Using sleeve from Seal Seat Remover Installer J 23128 install retainer so that outer edge is recessed 1 32 from compressor neck face Install clutch plate and hub assembly as
198. INNER SHELL Fig 13 Catalytic Converter Inner Shell d SEALING A COMPOUND RETAINING CHANNEL Fig 15 Installing Bottom Cover Retaining Channels Fig 14 Installing Bottom Cover Replacement TRUCK SUPP SERVICE FUEL TANK AND EXHAUST SYSTEM 8 7 Fig 16 Installing Bottom Cover Clamps TRUCK SUPP SERVICE ET 8 8 FUEL TANK AND EXHAUST SYSTEM DIAGNOSIS EXHAUST SYSTEM CONDITION POSSIBLE CAUSE CORRECTION Leaking Exhaust Gases Exhaust Noises Loss of engine power and or internal rattles in muffler Loss of engine power Leaks at pipe joints Damaged or improperly installed seals or packing Loose exhaust pipe heat tube extension connections Burned or rusted out exhaust pipe heat tube extensions Leaks at manifold or pipe connections Burned or blown out muffler Burned or rusted out exhaust pipe Exhaust pipe leaking at manifold flange Exhaust manifold cracked or broken Leak between manifold and cylinder head Dislodged turning tubes and or baffles in muffler Imploding inner wall collapse of exhaust pipe C Truck Tighten U bolt nuts at leaking joints to 30 foot pounds Replace seals packing as necessary Replace seals or packing as required Tighten stud nuts or bolts to specifications Replace heat tube extensions as required Tighten clamps at leaking connections to specified torque Replace gasket or packing as r
199. KA 000 P o o8 f CC EDEEAAUAM S898 teeletueluelwelwuw AE ENGINE FUEL 6M 29 Problem POSSIBLE CAUSE Fuel Restriction Dirt or water in fuel system Fuel level Main metering jet defective loose or incorrect part Power system in carburetor not functioning properly Power valve sticking in down position Vacuum leakage Problem POOR FUEL ECONOMY Engine needs complete tune up Choke valve not fully opening Fuel leaks Power system in carburetor not functioning properly Power valve sticking in up position High fuel level in carburetor or carburetor flooding Fuel being pulled from accelerator system into venturi through pump jet Air bleeds or fuel passages in carburetor dirty or plugged ENGINE RUNS UNEVEN OR SURGES CORRECTIVE ACTION Check all hoses and fuel lines for bends kinks or leaks Straighten and secure in position Check all fuel filters If plugged or dirty replace Clean fuel tank and lines Remove and clean carburetor Adjust float as specified in carburetor overhaul section Check for free float and float needle valve operation Replace as necessary Free up or replace as necessary It is absolutely necessary that all vacuum hoses and gaskets are properly installed with no air leaks The carburetor and manifold should be evenly tightened to specified torque Check engine compression Examine spark plugs if dirty or improperly gapped clean
200. L6 Engine the fan switch in any of the other three positions Fan Switch The blower FAN switch provides a means of selecting the amount of airflow from the system by regulating the speed of the blower motor There are however limitations to the HEATER AND AIR CONDITIONING 1A 5 control of blower speed To provide constant ventilation the blower motor electrical circuitry prevents the blower motor from being shut off when the ignition switch is on Therefore the blower speeds available are HI LO and two medium speeds The control panel also has a recirc override switch part of the master switch which overrides the blower speed switch and automatically provides HI blower speed when the system selector lever is MAX and the temperature lever is set to full COLD System Operation CK Truck System operation is as illustrated in Fig 7 Vacuum Schematic CK Truck The CK Truck air conditioning vacuum schematic is illustrated in Figure 8 Rear A C Blower Motor C69 G Van When air circulation only is desired the rear A C blower motor may be operated independent of the front A C blower motor and without the cooling function The rear blower motor resistor has been relocated to a position on the blower shroud at the rear of the vehicle See Section 12 of this manual for A C blower motor and heater blower motor A C equipped vehicles only wiring diagram revisions for 1976 TRUCK SUPP SERVICE o nnm nn
201. LUTCH GEAR BEARING LOCK RING CLUTCH GEAR BEARING ASSEMBLY CLUTCH GEAR EXPANSION PLUG FILLER PLUG TRANSMISSION CASE MAGNET CASE SEREBSSSSSIFFLSRASSRSSRESRASSBSAB MANUAL TRANSMISSION 7M 3 EXTENSION HOUSING TO CASE GASKET SPEEDOMETER DRIVER GEAR RETAINING CLIP TRANSMISSION REAR BEARING LOCK RING MAINSHAFT BEARING ASSEMBLY SPEEDOMETER DRIVE GEAR EXTENSION TO CASE WASHER EXTENSION TO CASE BOLT TRANSMISSION EXTENSION VENTILATOR ASSEMBLY EXTENSION HOUSING ASSEMBLY EXTENSION HOUSING BUSHING EXTENSION HOUSING OIL SEAL ASSEMBLY COUNTERGEAR THRUST WASHER COUNTERGEAR SPACER COUNTERGEAR ROLLET BEARINGS COUNTERGEAR SHAFT COUNTERGEAR SPRING PIN COUNTERGEAR 2ND amp 3RD SHIFTER FORK SHIFT FORK LOCKING SCREW IST amp 2ND SHIFTER INTERLOCK SPRING SHIFTER INTERLOCK PIN 1ST amp REVERSE SHIFT RAIL IST amp REVERSE SHIFT FORK 2ND amp 3RD SHIFTER INTERLOCK SPRING 2ND amp 3RD SHIFT RAIL REVERSE IDLER GEAR THRUST WASHER REVERSE IDLER GEAR SHAFT SPRING PIN IDLER GEAR SHAFT REVERSE IDLER GEAR BUSHING REVERSE IDLER GEAR REVERSE IDLER GEAR ASSEMBLY SEAL TRANSMISSION SHIFTER TRANSMISSION SHIFTER SHAFT amp LEVER ASSEMBLY Fig 2R Exploded View Tremec 3 Speed TRUCK SUPP OVERHAUL 7M 4 MANUAL TRANSMISSION Fig 3R Drain Transmission UPPER DETENT SPRING LONG Fig 4R Location of Upper Detent Spring Bearing Rollers clutch gear and countergear bearing rollers should be inspected
202. Light Duty Truck are basically carryover except for the G model truck bumper procedures listed below FRONT BUMPER Fig 1 Removal 1 Remove nuts securing bumpers to brackets and braces from left and right side Remove bumper 2 Remove the license plate support nut and bolts 3 If necessary to remove the braces and brackets remove screws securing brackets and braces to sheet metal NOTE The bumper may be removed with the brackets and braces attached 4 If equipped with bumper guards Fig 1 they may be removed from the face bar at this time Installation Reverse removal steps to install bumpers Refer to torque specifications for proper torque values REAR STEP BUMPER Fig 2 Removal 1 Remove nuts securing bumper to brackets and braces and remove bumper 2 Remove bracket and braces from vehicle NOTE The bumper may be removed with brackets and braces attached if necessary Installation Install in reverse order of removal Refer to torque specification for correct torque values Fig 2 G Model Rear Step Bumper TRUCK SUPP SERVICE SECTION 15 ACCESSORIES NOTE Except for the following changes all information listed in Section 15 of the 1974 Light Duty Truck Service Manual is applicable to 1976 light duty trucks Refer to 1974 Light Duty Truck Service Manual for any service procedure not contained herein CRUISE MASTER INDEX General DescHptlOni s rerit tet tete ee ae 15 1 Regulato
203. M Power Steering Fluid or II automatic Transmission Fluid or equivalent as necessary to bring level into proper range on filler cap indicator depending upon fluid temperature If at operating temperature approximately 150 F hot to the touch fluid should be between HOT and COLD marks HOT MARK COLD MARK Fig 5 Power Steering Filler Cap Indicator mm s Yn If at room temperature approximately 70 F fluid should be between ADD and COLD marks Fluid does not require periodic changing STEERING LINKAGE AND SUSPENSION Maintain correct front end alignment to provide easy steering longer tire life and driving stability Check control arm bushings and ball joints for wear Lubricate tie rods upper and lower control arms and ball joints at fittings with water resistant EP chassis lubricant which meets General Motors Specification GM 6031 M every 7 500 miles or 6 months Lubricate every 3 000 miles or 3 months whichever occurs first under the following conditions e Driving in dusty or muddy conditions e Extensive off road use NOTE Ball joints must be at 10 F or more before lubricating Keep spring to axle U bolts and shackle bolts properly tightened see Specifications Section for torque recommendations Check U bolt nuts after the first 1 000 miles of operation if the U bolt or
204. ND BEARING ASM 7 T pum FIXTURE E J 25008 1 HOLDING Fig 84 Installing Rotor and Bearing Assembly Dip new front head seal ring in 525 Viscosity oil and install seal in seal groove of front head Fig 87 Position oil hole in front head to be up when assembled to compressor cylinder to correspond with up position of compressor Install front head on compressor shaft Be sure seal ring stays in place and front head seats correctly to cylinder Tighten front head mounting screws to 18 22 foot pounds Install a new compressor shaft seal Install clutch rotor and bearing assembly clutch coil and pulley rim assembly to front head Fig 84 Before fully seating the assembly on front head be sure clutch coil terminals are in the proper location in relation to compressor and that the three protrusions on rear of clutch coil align with the locator holes in front head Install rotor and bearing assembly retaining ring and reassemble clutch plate and hub assembly Leak test compressor as described under Leak Testing the Compressor and correct any leaks found TRUCK SUPP OVERHAUL 1 34 AIR CONDITIONING COMPRESSOR HOLDING FIXTURE J 25008 1 OIL HOLE TO SHAFT SEAL AREA FRONT HEAD SEAL RING Fig 85 Alternate Installation of R 4 Rotor and Bearing Assembly THRUST AND BELLEVILLE WASHER REPLACEMENT 1 Remove two thrust and one belleville washer from compressor shaft Note the assemble
205. NG CONDENSER OUTLET HOSE AND TUBE Fig 9 Condenser Installation C K Models Replacement Fig 9 1 10 Disconnect battery ground cable 2 Purge the system of refrigerant 3 4 5 Remove the grille assembly Remove the radiator grille center support Remove the left grille support to upper fender support 2 screws Disconnect the condenser inlet and outlet lines and the outlet tube line at the right end of the condenser Cap or plug all open connections at once Remove the condenser to radiator support screws Bend the left grille support outboard to gain clearance for condenser removal Remove the condenser assembly by pulling it forward and then lowering it from the vehicle To install a new condenser reverse Steps 1 9 above Add one fluid ounce of clean refrigeration oil to a new condenser NOTE Use new rings coated with clean refrigeration oil when connecting all refrigerant lines Evacuate charge and check the system THERMOSTATIC SWITCH CK TRUCK The location of the thermostatic switch has been changed to provide more accurate sensing of refrigerant temperature and as a result improved system response and control The sensing element is attached by means of a clamp to the inlet tube of the evaporator The switch body is mounted on the bracket which supports the inlet tube in position at the evaporator case Replacement Disconnect the battery ground cable Disc
206. NGAGE TERMINAL TERMINAL OUTPUT TO SPEEDOMETER i TO TEE FITTING INPUT FROM TRANSMISSION LOCKNUT ORIFICE TUBE amp CONNECTOR ASSEMBLY FROM ENGINE VACUUM AIR FILTER amp SOLENOID HOUSING COVER Fig 2C Regulator Unit ACCESSORIES 15 3 4 The Cruise Brake Release Switch which is mounted on the brake pedal bracket disengages the system electrically when the brake pedal is depressed 5 The Cruise Brake Release Valve which is mounted on the brake pedal bracket disengages the system pneumatically when the brake pedal is depressed 6 The Cable and Casing Assemblies drive the regulator and speedometer MAINTENANCE AND ADJUSTMENTS The components of the Cruise Master System are designed to be replaced should they become inoperative The Regulator is cali brated in such a manner during manufacturing that overhaul operations are impractical However one adjustment may be made to the Regulator to correct speed drop or increase at the time of engagement REGULATOR FIG 3C One regulator adjustment is possible Engagement Cruising Speed Zeroing to remove any difference between engagement and cruising speed No regulator adjustment should be made however until the Servo Cable adjustment has been checked and vacuum hoses are checked for leaks kinks or other restrictions If the vehicle cruises at a speed a few mph above or below the engagement speed this error can be corrected w
207. NGLE DIAPHRAGM BOOSTER POWER PISTON GROUP ASSEMBLY The assembly procedure is the same as outlined in the 1974 Overhaul Manual however when assembling the support plate to the power piston be sure to press down and rotate the support plate clockwise until the locking lugs of the DELCO SINGLE AND DUAL STAKING FRONT AND REAR CYLINDER HOUSINGS Delco single and dual diaphragm booster cylinder housings are staked in two places 180 apart fig 1 When reassembling cylinder housings be sure the housings are A STAKED TABS 2 PLACES 180 APART B OPTIONAL STAKING LOCATIONS Fig 1 Delco Booster With Staked Tabs power piston come against the stops on the support plate GAUGING 1976 master cylinders incorporate shallow socket primary pistons therefore all gauging procedures should incorporate the use of Gauge J 22647 DIAPHRAGM BOOSTERS fully locked Using a 1 8 diameter rod or equivalent tool stake the two housings in two places 180 apart CAUTION 77e interlock tabs should not be used for staking a second time stake two of the remaining tabs When all tabs have been staked once the housing must be replaced UNSTAKED TAB SOCKET STAKING TAB SOCKET Fig 2 Staking Booster Tabs TRUCK SUPP OVERHAUL 5 2 BRAKES BENDIX HYDRAULIC BRAKE BOOSTER HYDRO BOOST INDEX Disassembly tees Cleaning and Inspection Assembly iie dd c etn OVERHAUL O
208. NT SERVO Removal 1 Remove rear servo cover attaching screws servo cover and gasket Discard gasket 2 Remove rear servo assembly from case fig 1B 3 Remove rear servo accumulator spring Hear Band Apply Pin Selection Model CL 4 Make band apply pin selection check to determine possible cause of malfunction B e NOTE There are six selective pins identified as shown in figure 3B Selecting proper pin is equivalent to adjusting band Attach band apply pin selection gauge J 21370 9 and J 21370 6 to transmission case lever pivot pin to rear with rear servo cover attaching screws fig 2B Attach tool attaching screws finger tight and check freeness of selective pin Torque attaching screws to 15 foot pounds and recheck pin to make certain it does not bind Apply 25 foot pounds torque to the lever on Tool J 21370 6 fig 2B Selection of the proper rear band apply pin is determined by the relation of the flat on Tool J 21370 9 to the flat machined area around the TRUCK SUPP OVERHAUL 7 4 AUTOMATIC TRANSMISSION hole on Tool J 21370 6 d Before removing gauging tool make note of the proper band apply pin to be used during assembly of the transmission as determined by the six selective pins identified as shown in figure 3B REAR SERVO ASSEMBLY s J 21370 6 J 21370 9 Fig 2B Checking Rear Band Apply Pin Model CL All Models Except CL a Attach band apply pin selection Gauge J 21
209. OCKOUT LEVER CHOKE VALVE CHOKE SECONDARY ENGINE FUEL 6M 39 FRONT VACUUM BREAK ADJUSTING SCREW PLUNGER CAM PULL OFF TANG FRONT VACUUM BREAK DIAPHRAGM ELECTRIC CHOKE ASSEMBLY UNLOADER TANG Ts FAST IDLE CAM FOLLOWER FAST IDLE ADJUSTING SCREW CHOKE SYSTEM ELECTRIC CHOKE T YPE Fig 43A Choke System the thermostatic coil and a large outer section for additional rapid heating of the thermostatic coil The ceramic resistor functions as follows AIR TEMPERATURE BELOW 50 F Electric current applied to the small section of the ceramic resistor causes the section to heat up and warm the thermestatic coil which allows gradual opening of the choke valve for good cold engine warm up performance As the small section of the ceramic resistor continues to produce heat a temperature sensitive bi metal disk causes a spring loaded contact to close also applying electric current to the large section of the ceramic resistor causing the large section to heat up Heat from the larger section of the ceramic resistor increases the rate of heat flow to the thermostatic coil for more rapid opening of the choke valve AIR TEMPERATURE 70 F AND ABOVE Electric current is applied directly to both the small section and through the spring contact to the large section of the ceramic resistor to provide a rapid heating of the thermostatic coil for greater choke valve opening when leaner air fuel mixt
210. OLTS NEEDLE BELOW 9 0 VOLTS STEP6 BATTERY OK CHARGE AS SPECIFIED BY TRUCK SUPP SERVICE ENGINE ELECTRICAL 6 27 SEQUENCE RESULT PLACE CARB ON HIGH STEP FAST IDLE CAM CONNECT VOLTMETER ACROSS BATTERY DISCONNECT COIL JUMPER a START ENGINE OR RECONNECT AU I DO NOT TOUCH HEI FEED WIRE ACCELERATOR PEDAL 7 IF VOLTAGE READS LOWER HEADLIGHTS H A THAN PREVIOUS AIC HI s T RADIO 49 IF VOLTAGE VOLTAGE T Im BLOWER TYPE IN DEFOGGER M READING CHECK VOLTAGE READING IUNDER 12 5 VOLTMETER RADIATOR INLET AND NEEDLE STOPS IS HOT GROUND GENERATOR TEST VOLTAGE REGULATOR WITH REPLACE APPROVED TESTER VOLTAGE REGULATOR OVERHAUL GENERATOR NOTE IF NOTHING HAS BEEN FOUND RE EDUCATE OWNER ON EXCESSIVE IDLING SLOW OR SHORT DISTANCE DRIVING WITH ALL ACCESSORIES ON TRUCK SUPP SERVICE 6Y 28 ENGINE ELECTRICAL PROBLEM battery OVERCHARGED uses too much water TEST BATTERY d USING BATTERY A LOAD TEST PROCEDURE CONNECT VOLTMETER ACROSS 3 WAIT UNTIL UPPER RADIATOR INLET CHECK FOR GROUNDED BRUSH LEAD LIP CHECK FOR SHORTED FIELD OHMMETER WINDINGS SEE SERVICE MANUAL FOR SPECIFICATIONS GENERATOR 1 BATTERY OK BATTERY REPLACE NOT OK BATTERY PLACE CARB ON HIGH STEP FAST IDLE CAM VOLTMETER NEEDLE STOPS IF NOT SHORTED CARBURETOR START ENGINE DO NOT TOUCH A
211. OR DAMAGED VACUUM HOSES ALSO CHECK VACUUM FITTINGS CHECK SPEEDOMETER CABLE ROUTING IT MUST NOT BE KINKED OR HAVE TOO SHARP A TURNING RADIUS NOT LESS THAN 6 RADIUS CHECK DRIVE CABLE FOR DISTORTED OR BENT TIPS FERRULES MUST BE SNUG CHECK FOR A BINDING THROTTLE LINKAGE CONDITION CHECK ADJUSTMENT OF BRAKE RELEASE SWITCH amp VACUUM RELEASE VALVE SEE SERVICE amp ADJUSTMENTS CHECK FOR PROPER OPERATING PROCEDURE OF THE ENGAGE SWITCH SEE FIG 1 IF STEPS 1 THROUGH 6 DO NOT SOLVE THE PROBLEM PROCEED WITH CHECK II SPECIAL NOTE PERTAINING ENGAGEMENT CRUISING SPEED ZEROING IF THE CAR CRUISES BELOW ENGAGEMENT SPEED SCREW THE ORIFICE TUBE OUTWARD IF THE CAR CRUISES ABOVE THE ENGAGEMENT SPEED SCREW THE ORIFICE TUBE INWARD EACH 1 4 TURN WILL CHANGE THE CAR SPEED APPROXIMATELY ONE MPH ENGAGEMENT ACCURACY TESTING TO BE DONE AT 60 MPH SNUG UP LOCK NUT AFTER EACH ADJUSTMENT CAUTION DO NOT REMOVE ORIFICE TUBE FROM CASTING Fig 8C System Diagnosis Chart No 1 TRUCK SUPP SERVICE 15 10 ACCESSORIES PRELIMINARY PROBLEM UNPLUG TWO TERMINAL RECONNECT INSPECTION NNECTOR AS PER FIG 9 CHECK II COMPLETE CHECK PROCEED IF CHECK 1 DOES NOT SOLVE THE CONNECTOR REGULATOR WHITE WIRE PLUGGED TO HOLD TERMINAL BROWN WHITE WIRE NOT CONNECTED TURN ON IGNITION KEY DO NOT START ENGINE AND DEPRESS ENGAGE SWITCH HALFWAY AND HOLD THUNK 15 NORMAL RESULT REGULATOR
212. PERATIONS The Bendix Hydraulic Brake Booster utilizes the hydraulic 2 pressure supplied by the power steering pump to provide power assist for brake applications fig 3 The dual master 3 cylinder is mounted to the output push rod end of the booster The procedures below include removal of the mounting bracket even though it is not necessary to remove the bracket for overhaul of the internal assembly Disassembly Fig 4 1 Secure the booster in a vise bracket end up and use a hammer and chisel to cut the bracket nut that secures the mounting bracket to the power section cut the nut at the open slot in the threaded portion of the housing Be careful to avoid damage to the threads on the booster hub Spread the nut and remove it from the power section Then remove the mounting bracket PRESSURE PORT RETURN PORT 10 11 GEAR PORT MOUNTING BRACKET OUTPUT PUSH BOOSTER POWER SECTION 12 Fig 3 Bendix Hydro Boost Brake Booster PEDAL ROD 8 Remove the pedal rod boot if equipped by pulling it off over the pedal rod eyelet Place Tool J 24569 around the pedal rod and resting on the input rod end as shown in Figure 5 Place a punch or similar tool through the pedal rod from the lower side of Tool J 24569 Push the punch on through to rest on the higher side of the tool Lift up on the punch to shear the pedal rod retainer remove the pedal rod Remove the remnants of the rubber grommet from th
213. Q Check choke mechanism for free operation Any binding caused by petroleum gum formation on choke shaft or from damage should be corrected 1 Remove thermostatic coil rod from choke coil lever 2 Rotate coil lever counterclockwise until the choke valve is closed 3 Hold down on choke coil rod with rod against stop 4 Rod should fit notch in choke coil lever 5 Bend coil rod if necessary to adjust 6 Install rod to lever CHOKE VALVE COMPLETELY S THERMOSTATIC COIL ROD FROM LEVER 2 ROTATE COIL LEVER COUNTERCLOCKWISE UNTIL CHOKE VALVE IS CLOSED ROD SHOULD FIT IN NOTCH IN LEVER ES BEND ROD TO ADJUST 3 HOLD DOWN ON Ex ROD AGAINST STOP Fig 15Q Choke Coil Rod Adjustment SECONDARY THROTTLE VALVE LOCK OUT ADJUSTMENT Secondary Lock Out Lever Clearance 1 Hold choke valve and secondary throttle valves closed 2 Using 015 plug gauge measure clearance between lock out pin and lock out lever as shown 3 If necessary bend lock out pin at point shown to obtain 015 clearance Opening Clearance 4 Hold choke valve wide open by pushing down on tail of fast idle cam 5 Hold secondary throttle valves slightly open 6 Using 015 plug gauge measure clearance between end of lock out pin and toe of lock out lever as shown 7 If necessary file off end of lock out pin to obtain 015 clearance SECONDARY CLOSING ADJUSTMENT FIG 160 Pre set
214. R ASSM t N HOT AIR PIPE LINKAGE Fig 9C Air Cleaner Operation TRUCK SUPP SERVICE 6M 68 ENGINE FUEL This system is designed to improve carburetor operation and engine warm up characteristics It achieves this by keeping the air entering the carburetor at a temperature of at least 85 F Heavy Duty Emissions 100 F Light Duty Emissions except at wide open throttle The thermostatic air cleaner system includes a temperature sensor a vacuum motor and control damper assembly mounted in the air cleaner vacuum control hoses manifold heat stove and connecting pipes The vacuum motor is controlled by the temperature sensor The vacuum motor operates the air control damper assembly to regulate the flow of hot air and under hood air to carburetor The hot air is obtained from the heat stove on the exhaust manifold AIR CLEANER ELEMENT REPLACEMENT Paper Element 1 Remove air cleaner cover 2 Remove and discard air cleaner element 3 Clean bottom section of air cleaner and inspect cover seal for tears or cracks Replace seal if damaged 4 Install new element in bottom section of air cleaner with either end up 5 Install air cleaner cover Do not over torque wing nut s Polywrap Element Remove air cleaner cover 2 Remove element 3 Remove polywrap band from paper element and discard element fig 10C 4 WING NUT e T ORQUE AT 20 LBS IN T 1 NOTE Polyurethane Band must wrap
215. R ON HIGHEST STEP OF CAM Fig 51 Automatic Choke Coil Adjustment Hot Air of choke coil lever pick up arm 2 Place fast idle cam follower on the highest step of the fast idle cam 3 Rotate cover and coil assembly counterclockwise until choke valve just closes 4 Align index point on cover with specified index point on choke housing 5 Tighten retaining screws Electric Fig 52 3 SET MARK ON ELECTRIC CHOKE TO SPECIFIED POINT ON CHOKE COR ME 2 PLACE FAST IDLE CAM FOLLOWER ON HIGH STEP OF CAM LOOSEN THREE RETAINING SCREWS Fig 52 Automatic Choke Coil Adjustment Electric 1 Install the electric choke assembly in choke housing making sure coil tang contacts bottom side of inside choke coil lever pick up arm 2 Place fast idle cam follower on high step of cam 3 Rotate cover and coil assembly counterclockwise until choke valve just closes 4 Align index point on cover with specified mark on housing 5 Install cover retainers and screws and tighten securely TRUCK SUPP SERVICE 6M 44 ENGINE FUEL NOTE Ground contact for the electric choke is provided by a metal plate located at the rear of the choke assembly DO NOT INSTALL A CHOKE COVER GASKET BETWEEN THE ELECTRIC CHOKE ASSEMBLY AND THE CHOKE HOUSING CAUTION Do not immerse the electric choke assembly n any cleaning solution or severe damage can result Electric Choke Diagnosis and Checking Procedure In o
216. RIVE ON HOIST m BUMPER JACK LIFTING FLOOR JACK OR HOIST LIFT Fig 6 Model Lifting Points TRUCK SUPP SERVICE GENERAL INFORMATION AND LUBRICATION 0 19 p 04 x Y OVO bey e Lubricati Type of Lower Control Arms 7 500 Miles Chassis Lubricant Upper Control Arms 7 500 Miles Chassis Lubricant L5 6 7 Intermediate Steering 7 500 Miles Chassis Lubricant 2 places as required Shaft PA10 m Tie Rod Ends 7 500 Miles Chassis Lubricant 30 000 Miles Whl Brg Lubricant i 2 pper and Lower Control 7 500 Miles Chassis Lubricant 4 places as required wa rere fe i wi METERS EN Wheel Bearings Steering Gear Do not Lubricate Maintenance Schedule Check add fluid when necessary Keep even w filler plug See Lubrication Section 30 000 Miles Air Cleaner Element 30 000 Miles Delco Supreme required No 11 or DOT 3 fluids GL 5 Dexron JI or equivalent Master Cylinder As required As required Transmission Manual Automatic 7 500 Miles 7 500 Miles Engine As required Carburetor Linkage V 8 7 500Miles EngineOil Asrequred o oOo y Brake and Clutch Pedal 7 500 Miles As required 55565 Springs Universal Joints 7 500 Miles Chassis Lubricant As required fee ue e a L
217. RMEDIATE CLUTCH The procedure for disassembly inspection and assembly remains the same with the exception of these changes or additions Disassembly Disassembly procedure step number 4 and 5 should read 4 Remove direct clutch backing plate 5 Remove direct clutch plates as follows a Model CA Remove four 4 composition faced and four 4 flat steel clutch plates from the direct clutch housing b Models CG CJ CM CP CR and CT Remove five 5 composition faced and five 5 flat steel clutch plates from the direct clutch housing Models CL and CZ Remove 6 composition faced and six 6 flat steel clutch plates from the direct clutch housing NOTE The production built transmissions use a direct clutch piston without a check ball The forward and direct clutch pistons look almost the same Make sure the direct clutch piston is identified during disassembly so it will be re assembled into the direct clutch housing The service replacement direct clutch piston contains a check ball Models CL and CZ contain 2 check balls The production built direct clutch piston will be aluminum or stamped steel Inspection Inspection procedure add steps number 6 7 and 8 which will read 6 Inspect clutch piston for cracks 7 Inspect fourteen 14 release springs for collapsed coils or signs of distortion NOTE The 14 direct clutch release springs are not serviced If one or more of these springs require
218. SOLENOID BATTERY PA NEUTRAL SAFETY amp j lt BACKING LAMP SW TRANS SOLENOID gh CABLE STARTING MOTOR ZZ SOLENOID G 10 FUEL METER LEFT SIDE RIGHT SIDE VIEW A Fig 11 30 Truck V 8 LF8 Engine Wiring TRUCK SUPP SERVICE CHARGE INDICATOR VENT 2 TERMINAL Fig 1b Freedom Battery FREEDOM BATTERY The Freedom Maintenance Free Battery fig 1b has more electrolyte in the cells than regular vent cap type batteries With the reduced water usage water never needs to be added Actually water can not be added There are no vent plugs in the cover The battery is completely sealed except for 2 small vent holes on the side These vent holes allow what small amount of gases that are produced in the battery to escape The special chemical composition inside the battery reduces the production of gas to an extremely small amount at normal charging voltages A charge indicator located in the cover indicates state of charge This feature will be fully explained in the following paragraph Testing Freedom Battery Visual Inspection Check for obvious damage such as a cracked or broken case or cover that could permit loss of electrolyte If obvious physical damage is noted replace battery Also determine cause of damage and correct as required Charge Indicator Dark Green Dot Visible Fig 2b If the charge indicator is dark and has a green dot in the center the battery is
219. SUPP SERVICE 6M 48 ENGINE FUEL DIAGNOSIS GENERAL When carburetor troubles are encountered they can usually be diagnosed and corrected with an adjustment as outlined below and under Maintenance and Adjustments Before diagnosing the carburetor as the trouble area check and diagnose the following 1 Fuel Supply 2 Fuel pump pressure and volume 3 Plugged fuel filter or fuel lines 4 Linkage and emission control systems 5 Engine compression 6 Ignition system firing voltage 7 Ignition spark timing 8 Spark plugs 9 Secure intake manifold 10 Engine temperature Use the following tables to diagnose carburetor Problem ENGINE IDLES ROUGH AND STALLS idle speed setting Manifold vacuum hoses disconnected or improperly in stalled Carburetor loose on intake manifold Intake manifold is loose or gaskets are defective Carburetor flooding NOTE Also check carburetor flooding when engine cranks turn over but will not start or starts hard when cold Dirt in idle channels Poor secondary throttle valve alignment Re set idle speed under maintenance and adjustment Check all vacuum hoses leading into the manifold or carburetor base for leaks or being disconnected install or replace as necessary Torque carburetor to manifold bolts Using a pressure oil can spray light oil or kerosene around manifold legs and carburetor base If engine RPM changes tighten or replace the manifold gaskets
220. Spring Bracket Nut Spacer Plug O Ring Linkage Bracket Check Valve Ball Spool Plug Booster Cover Accumulator Check Valve Snap Ring Cover to Housing Seal Ring Seal Piston Return Spring Input Rod Seals Piston Seal Spring Retainer Input Rod and Piston Assy Booster Housing Housing to Cover Bolts Spool Assembly Tube Seat Inserts Fig 4 Booster Components Typical 13 Remove the input rod seals from the input rod end and Cleaning and Inspection the piston seal from the piston bore in the housing discard the sedis 1 Clean all metal parts in a suitable solvent Be careful to avoid losing small parts 14 Remove the plunger seat spacer and ball from the accumulator valve bore in the flange of the booster housing Remove the O ring from the seat discard the O ring 2 Inspect the valve spool and the valve spool bore in the booster housing for corrosion nicks scoring or other damage Discoloration of the spool or bore particularly M in the grooves is not harmful and is no cause for 15 Thread a screw extractor into the opening in the check concern valve in the bottom of the accumulator valve bore and remove the check valve from the bottom of the bore Discard the check valve and O ring 3 If the valve spool or the valve spool bore has nicks or scoring that can be felt with a fingernail particularly on the lands the entire boo
221. T SIDE HEATER BLOWER 2 VIEW C Fig 7 6 10 thru 30 Truck V 8 LF4 LG9 LS9 Engine Wiring TEMP SWITCH COOLANT RECOVERY HEATER BLOWER 4 WIRE ASM i RIGHT SIDE Z FWD BAT CABLE ENG HARN 12H NOTE THIS CONNECTION MUST BE POSITIONED AS SHOWN A NOTE PRESS BOOT OVER f TERMINAL WITH SMALL END DOWN COOLANT RECOVERY TANK ENG HARN RIGHT SIDE TRUCK SUPP SERVICE ENGINE ELECTRICAL 6Y 5 PCV HOSE NOTE PRESS BOOT OVER TERMINAL WITH SMALL END DOWN RIGHT SIDE BACKING LAMP switcH 20 VEW AA FUEL METER WIRE STARTING MOTOR SOLENOID FUEL PIPE NOTE PRESS BOOT OVER TERMINAL WITH SMALL END DOWN STARTING MTR SOLENOID NEUTRAL SAFETY BACKING LAMP SWITCH BAT CABLE amp BACKING LAMP SWITCH LEFT SIDE RIGHT SIDE Fig 9 P 10 thru 30 Truck Except 32 Truck V 8 159 Engine Wiring TRUCK SUPP SERVICE MEN e OA E 6Y 6 ENGINE ELECTRICAL GENERATOR TO JUNCTION rw NEUTRAL SAFETY amp BACKING LAMP CONNECTOR lt NOTE PRESS OVER TERMINAL WITH SMALL END DOWN TEMP SWITCH LEAD BATTERY CABLE NEUTRAL SAFETY amp BATTERY CABLE BACKING LAMP WIRE ASM 7A LEFT SIDE TO DASH PANEL TO IDLE s aA x c STOP SOL IM 9 x N A BATTERY CABLE SWITCH ASM X 7 va y STARTING PURPLE MOTOR VIEW B
222. TAKE Refer to figure 21C for carburetor air intake used on CK trucks DRILL 7 64 HOLE IN CENTER POSITION OF STRAP SPOTWELDS VACUUM DIAPHRAGM INSTALL REPLACEMENT RETAINING SENSOR ASSM IN SAME STRAP POSITION AS ORIGINAL ASSM Fig 19C Vacuum Diaphragm Replacement TRUCK SUPP SERVICE 6M 72 ENGINE FUEL Fig 20C Removing Sensor Unit Y I AIR INLET DUCT Ray AIR INLET AX ss Aa A ENGINE N F f f SS 8 ENGINE Fig 21C Carburetor Air Intake CK FUEL PUMP GENERAL The fuel pump is a diaphragm type The pump is actuated by an eccentric located on engine camshaft On in line engine the eccentric actuates the rocker arm On V 8 engines a push rod located between camshaft eccentric and fuel pump actuates the pump rocker arm Because of design this pump 15 serviced as an assembly only INSPECTION The fuel pump figs 22C through 25C should be checked to make sure mounting bolts and inlet and outlet connections are tight TEST Always test pump while it is mounted on engine and be sure there is gasoline in tank The line from the tank to the pump is the suction side of system and the line from pump to carburetor is the pressure side of system A leak on pressure side therefore would be made apparent by dripping fuel but a leak on the suction would not be apparent except for its effect of reducing volume of fuel on pressure side 1 Tighten any l
223. THROTTLE FAST IDLE CAM CHOKE COIL HOUSING CANISTER CHOKE HEAT INLET PURGE TUBE Fig 19 2GC Carburetor Front ENGINE FUEL 6M 19 CLEAN AIR TUBE 9 CHOKE CLOSING ASSIST SPRING CHOKE VACUUM 7 d BREAK DIAPHRAGM 4 FULL ipee SPARK PORT EXHAUST GAS RECIRCULATION THERMOSTATIC E VACUUM PORT COIL Fig 20 2GC Carburetor 3 4 View THEORY OF OPERATION FLOAT SYSTEM Fig 21 The float system controls the level of the fuel in the carburetor bowl Fuel level is very important because it must be maintained to give proper metering through all operating ranges As fuel is used from the carburetor bowl the plastic float drops moving the float needle off its seat allowing more fuel to enter the bowl thereby keeping the fuel level constant The fuel bowl is internally vented by a large drilled hole which leads from inside the air horn bore to a vapor dome above the fuel in the float bowl The internal vent provides a balance in air pressure to maintain constant air fuel mixture ratios Also the large internal hole vents fuel vapors that form during periods of hot engine operation for improved hot idle and restart IDLE LOW SPEED SYSTEM Fig 22 The idle system is used to provide the proper mixture ratios required during idle and low speed operation of the engine The idle system consists of the idle tubes idle passages idle air bleeds idle mixture needles off idle discharge ports and idle needle dis
224. TTLE RETURN 27 S CONTROL VALVE _ Bc bo G20 amp 30 400 8 CAL We gt G gt PA PURPLE STRIP P ACTUATOR 7 DJ PURPLE STRIP P x 350 V8 4 BBL EGR VALVE DIVERTER gt N 75 LZ EFE we ACTUATOR SS SPARK DIVERTER VALVE Fig 4 Emission Hose Routings G VALVE AIR lt CLEANER q N G10 350 V8 4 BBL CAL THROTTLE RETURN CONTROL D PURPLE STRIP THROTTLE RETURN CONTROL VALVE G20 amp 30 350 400 V8 CAL TRUCK SUPP SERVICE EMISSION CONTROL SYSTEMS ST 5 EARLY FUEL EVAPORATION SYSTEM EFE GENERAL The early fuel evaporation EFE system improves cold engine warm up by routing hot exhaust gases under the base of the carburetor which results in better atomization of fuel Fig 5 EFE System L6 in a cold engine and helps reduce exhaust emissions during cold drive away The EFE system consists of a vacuum controlled actuator which is linked to a stainless steel exhaust heat valve and a method of controlling vacuum source When a cold engine is started full vacuum pulls the spring loaded diaphragm in the actuator and actuator rod closes the exhaust heat valve This causes hot gases to be routed to the base of the carburetor On six cylinder engine the vacuum to the EFE actuator is controlled by an oil temperature thermal vacuum switch TCS located in t
225. Tighten bolts 20 to 25 foot pounds torque If removed install backup light switch in extension housing and TCS switch in case Tighten switches to 15 to 20 foot pounds torque TRUCK SUPP OVERHAUL SPECIAL TOOLS f 2 1 J 24433 FRONT BEARING INSTALLER 2 1 22609 REAR BEARING INSTALLER 3 1 25232 COUNTER GEAR DUMMY SHAFT 4 1 8433 1 FRONT BEARING REMOVER 5 J 6654 1 FRONT BEARING REMOVER 6 J 25233 BEARING RETAINER OIL SEAL INSTALLER 7 1 5154 EXTENSION HOUSING SEAL INSTALCER 34 5778 EXTENSION HOUSING BUSHING INSTALLER J 8157 01 REAR BEARING REMOVER Fig 25R Tremec Special Tools MANUAL TRANSMISSION 7M 11 TRUCK SUPP OVERHAUL 7M 12 MANUAL TRANSMISSION FOUR SPEED MUNCIE TRANSMISSION CH 465 INDEX Transmission Assembly Mainshaft Assembly ASSEMBLY Fig 1X 1 In reassembling the transmission cover care must be used in installing the shifter shafts They should be installed in the order shown in Fig 2X namely reverse 3rd 4th and Ist 2nd Figure 1X illustrates difference between shafts Place fork detent ball springs and balls in position in holes in cover Start shifter shafts into cover depress dentent balls with small punch and push shafts on over balls See Fig 2X Transmission Cover Interlock Balls 3rd 4th Shifter Shaft Reverse Shifter Shaft Fork Retaining Pin Plugs Detent Ball Detent Spring 3rd 4th Shifte
226. To remove the pump plunger stem from the inner pump lever it will be necessary to break off the swedged or flattened end of the pump plunger stem This should not be done unless pump assembly replacement is necessary such as during overhaul The service pump assembly uses a grooved pump plunger stem and retaining clip After removing the inner pump lever and pump assembly remove the outer pump lever and shaft assembly from air horn Remove the plastic washer on pump plunger shaft 12 Remove air horn gasket from air horn 13 Remove fuel inlet baffle next to needle seat 14 Remove two choke valve attaching screws then remove choke valve Care should be taken when removing attaching screws so that the choke shaft will not be bent It may be necessary to file off staked ends on choke valve screws before removing 15 Remove choke valve shaft from air horn 16 Remove the fast idle cam rod and lever from the choke shaft Float Bowl 1 Remove pump plunger return spring from inside pump well Then remove aluminum check ball from bottom of pump well by inverting bowl Fig 5C 2 Remove main metering jets power valve and gasket from inside float bowl 3 Remove three screws holding venturi cluster to float bowl and remove cluster and gasket Then remove the plastic main well inserts in the main well cavity 4 Using a pair of long nosed pliers remove pump discharge spring retainer Fig 6C Then spring and check ball may als
227. Tools uuu wa TRUCK SUPP OVERHAUL 6M 6 CARBURETOR GENERAL Flooding stumble on acceleration and other performance complaints are in many instances caused by the presence of dirt water or other foreign material in the carburetor To aid in diagnosing the cause of complaint the carburetor should be carefully removed from the engine without draining fuel from the bowl The contents of the fuel may then be examined for dirt or water problems as the carburetor is disassembled The following is a step by step sequence by which the model 2GC carburetor Fig 1C may be completely disassembled and reassembled Adjustments may be made and various parts of the carburetor may be serviced without completely disassembling the entire unit Refer to service section for external adjustments AIR HORN ACCELERATOR PUMP ROD THROTTLE FAST IDLE CAM CHOKE COIL HOUSING CANISTER CHOKE HEAT INLET PURGE TUBE Fig 1C Rochester 2GC Carburetor DISASSEMBLY Air Horn 1 Remove fuel inlet filter nut and gasket and remove filter and spring 2 Disconnect lower end of pump rod from throttle lever by removing spring clip Fig 2C 3 Remove upper end of pump rod from pump lever by rotating rod out of hole in lever 4 Remove the vacuum break diaphragm hose from tube on throttle body and tube on vacuum break diaphragm unit Then remov
228. U bolt nuts are changed in service HOOD LATCH AND HOOD HINGE Every 7 500 miles or 6 months whichever occurs first lubricate hood latch assembly and hood hinge assembly as follows 1 Wipe off any accumulation of dirt or contaimination on latch parts 2 Apply lubriplate or equivalent to latch pilot bolt and latch locking plate 3 Apply light engine oil to all pivot points in release mechanism as well as primary and secondary latch mechanisms 4 Lubricate hood hinges 5 Make hood hinge and latch mechanism functional check to assure the assembly is working correctly BODY LUBRICATION Normal use of a truck causes metal to metal movement at certain points in the cab or body Noise wear and improper operation at these points will result when a protective film of lubricant is not provided For exposed surfaces such as door checks door lock bolts lock striker plates dovetail bumper wedges etc apply a thin film of light engine oil Where oil holes are provided in body parts a dripless oil can be safely used but any lubricant should be used sparingly and after application all excess should be carefully wiped off TRUCK SUPP SERVICE The seat adjusters and seat track ordinarily overlooked should be lubricated with water resistant EP chassis lubricant which meets General Motors Specification GM 6031 M There are other points on bodies which may occasionally require lubrication and which are difficult to serv
229. UL 4 2 REAR AXLE DIFFERENTIAL Salisbury 3750 8 7 8 Chevrolet Salisbury 3750 8 7 8 Chevrolet Satisbury 4000 8 7 8 Chevrolet Salisbury 3500 8 7 8 Chevrolet Chevrolet Salisbury 3100 8 7 8 Salisbury 3100 8 1 2 Except C20 Crew Chevrolet Salisbury 5700 10 1 2 Cab C20 Crew Cab Chevrolet Salisbury 75003 10 1 2 o Chevrolet Salisbury 5700 10 1 2 G20 Chevrolet Chevrolet Salisbury 5700 10 1 2 Salisbury 3500 8 7 8 Except Dual C30 Chevrolet Salisbury 7500 10 1 2 Camper Dual Salisbury 7500 10 1 2 C30 Wheel Dana fox Chevrolet Salisbury 7900 10 1 2 Chevrolet Camper CH Chevrolet Salisbury 5700 10 1 2 Dual Dana Salisbury 6200 9 3 4 Salisbury 75003 Fig 1 Axle Chart Chevrolet Banjo 11 000 124 47 Dual G30 Wheel Dana ZERO THE INDICATOR WITH THE PROBE ON THE HIGH POINT OF THE GAUGING SURFACE SWING THE PROBE OFF THE GAUGE PLATE THE INDICATOR NEEDLE 7 X WILL MOVE TOWARD THE PROPER NUMBER WHICH INDICATES THE REQUIRED SHIM FOR A NOMINAL PINION THIS NUMBER IS THE Z CORRECT SHIM THICKNESS FOR A NOMINAL PINION Fig 2 Correct Use of Dial Indicator TRUCK SUPP OVERHAUL SECTION 5 BRAKES The 1976 brake boosters are essentially the same as those described in the 1974 Overhaul Manual with the following exceptions DELCO SI
230. UNT OF OIL CONTAMINATED OIL DRAINED ANY AMOUNT DRAIN AS MUCH OIL AS POSSIBLE FROM SYSTEM FROM SYSTEM FLUSH SYSTEM WITH REFRIGERANT 11 REPLACE DRIER DESSICANT AND INSTALL NEW 525 VISCOSITY OIL IN NEW COMPRESSOR A 6 COMP 10 1 2 075 R 4 COMP 6 025 Fig 5 Compressor Oil Charge for 6 R 4 Unit Replacement TRUCK SUPP SERVICE HEATER AND AIR CONDITIONING 1A 7 UND p ECONOMY E NORM VENT HEATER Fig 6 Heater Air Conditioning Control Assembly CK Truck SYSTEM OPERATION CK TRUCK SELECTOR BLOWER AIR AIR HEATER A C HEATER LEVER SPEEDS SOURCE ENTERS DOOR DEFROSTER POSITION VEHICLE OPEN TO DOOR OPEN TO OUTSIDE FLOOR OUTLETS HEATER HEATER MAX AIC INSIDE OUTLETS HEATER NORM A C OUTSIDE DASH OUTLETS HEATER iC mane o lt _ HTA C A outst DEEROST OUTLETS HEATER DEFROST NOTE 100 Inside air is not available some bleed through of outside air is allowed Fig 7 System Operation CK Truck TO VACUUM TEE it BLACK EVAP amp BLWR ASM VACUUM TANK FRONT OF DASH HTR amp DEF 5 e tul VACUUM HOSE A C CONTROL e VACUUM ACTUATOR Fig 8 Air Conditioning Vacuum Schematic CK Truck TRUCK SUPP SERVICE 1A 8 HEATER AND AIR CONDITIONING SERVICE OPERATIONS CONDENSER CK MODEL NOTE INSTALL UPPER ATTACHMENTS FIRST WHEN INSTALLI
231. YSTEM OF REFRIGERANT as outlined earlier in the Service Manual Remove 1 After first purging the system of refrigerant remove the clutch plate and hub assembly and shaft key as described in Compressor Clutch Plate and Hub Asm Removal procedure 2 Pry out the sleeve retainer and remove the absorbent sleeve Remove the shaft seal seat retaining ring using Snap Ring Pliers J 5403 21 See Fig 18 3 Thoroughly clean inside of compressor neck area surrounding the shaft the exposed portion of the seal seat and the shaft itself This is absolutely necessary to prevent any dirt or foreign material from getting into compressor 4 Place Seal Protector J 22974 over the end of the shaft to prevent chipping the ceramic seat Fully engage the knurled tangs of Seal Seat Remover Installer J 23128 into the recessed portion of the seal seat by turning the handle clockwise Lift the seat from the compressor with a rotary motion Fig 19 CAUTION DO NOT tighten the handle with a wrench or pliers however the handle must be hand tightened securely to remove the seat AIR CONDITIONING COMPRESSOR 1 9 SEAL SEAT REMOVER J 23128 O RING REMOVER J 9553 7 Fig 19 Removing Shaft Seal Seat and O Ring 5 With Seal Protector J 22974 still over the end of the shaft engage the tabs on the seal assembly with the tangs on Seal Installer J 9392 by twisting the tool clockwise while pressing the tool down Then lift the seal ass
232. a short period of time 2 Pedal application through run out will not necessarily be smooth due to the internal 4 On a spike brake application a slight pedal ratio change It is possible to push the pedal kick back may be felt past run out because of the higher pedal ratio At run out of the vacuum booster the pedal 5 If the vehicle is started with the pedal de just becomes hard pressed the pedal will fall away slightly then return back to approximately the original position NO BOOST HARD PEDAL Preliminary Check With the engine stopped depress the brake pedal several times ta eliminate all accumulator reserve from the system Hold the brake pedal depressed with medium pressure 25 to 35 Ibs start the engine If the unit is operating correctly the brake pedal will fall slightly and then push back against the driver s foot remaining at about the same position If the booster is not operating correctly the trouble may be one of the following causes Probable Cause Remedy 1 Loose or broken power steering 1 Tighten or replace the belt pump belt 2 No fluid in power steering reservoir 2 Fill reservoir and check for external leaks 3 Leaks in power steering booster or 3 Replace defective parts accumulator hoses 4 Leaks at tube fittings power steering 4 Tighten fittings or replace tube booster or accumulator connettions seats if defective 5 External leakage at accumulator 5 Replace booster 6 Faulty booster piston
233. ace size PROPER SELECTION OF THRUST RACES AND BALL SEATS IS OF EXTREME IMPORTANCE 15 16 Measure clearance between rear ball of No 1 Piston and axial plate in following manner a Select a suitable combination of well oiled Feeler Gage leaves to fit snugly between ball and axial plate b Attach a spring scale reading in 1 increments to the feeler gage A distributor point checking scale or Spring Scale J 544 may be used c Pull on Spring Scale to slide Feeler Gage stock out from between ball and axial plate and note reading on Spring Scale as Feeler Gage is removed Fig 40 Reading should be between 4 and 8 ounces d If reading in Step c above is under 4 OR over 8 ounces reduce or increase thickness of Feeler Gage leaves and repeat Steps a through c above until a reading of 4 to 8 ounces is obtained Record clearance between ball and axial plate that results in th 4 to 8 ounce pull on Spring Scale Now rotate shaft 120 and repeat Step 15 between same ball and axial plate Record this measurement If shaft is hard to rotate install shaft nut onto shaft and turn shaft with wrench Rotate shaft another 120 and again repeat Step 15 between these same parts and record measurements Select numbered shoe disc corresponding to minimum feeler gage reading recorded in the three checks above See example in Fig 42 Place shoe discs in Parts Tray J 9402 compartment corresponding to Pis
234. acer 9 From the next bore down remove the 1 2 accumulator valve train as follows a Models CA CG CP and CR remove the grooved retaining pin bore plug 1 2 accumulator valve and spring b Models CJ and CL Remove the grooved retaining pin bore plug 1 2 accumulator valve c Models CT CM and CZ Remove the grooved retaining pin bore plug 1 2 accumulator secondary spring and 1 2 accumulator valve Inspection Q Q N NOTE See figure 9B Do not remove the teflon oil seal ring from the front accumulator piston unless the oil seal ring requires replacement For service the oil seal ring is cast iron Inspect all valves for scoring cracks and free movement in their respective bores Inspect bushings for cracks scratches or distortion Inspect body for cracks or scored bores Check all springs for distortion or collapsed coils Inspect accumulator piston and oil seal ring for damage Assembly l 2 3 Install front accumulator spring and piston into valve body Install Special Tools J 22269 and J 24675 and compress spring and piston and secure with retaining E ring Install the 1 2 accumulator valve train into the lower left hand bore as follows a Model CA CG CP and CR Install the 1 2 accumulator spring and 1 2 accumulator valve stem end out into bore Place the bore plug into valve bore and install grooved retaining pin from cast surface side of the valve body
235. aft lockout clutch and drive sprocket assembly in the range box aligning tab on bearing retainer with notch in gasket 5 Connect lockout clutch shift rail to the connector link Fig 6F Removing Rear Output Shaft From Bearing and position rail in housing bore Rotate shifter shaft lowering shift rail into the housing to prevent the link and rail from being disconnected 6 Install drive chain in chain housing positioning the chain around the outer wall of the housing 7 Install the chain housing on the range box engaging the shift rail channel of the housing to the shift rail Position chain on the input drive sprocket 8 Install the front output sprocket in the case engaging the drive chain to the sprocket Rotate clutch drive gear to assist in positioning chain on the drive sprocket 9 Install the shift fork on the clutch assembly and the shift rail then push the clutch assembly fully into the drive sprocket Install roll pin retaining shift fork to shift rail 10 Install front output shaft bearing 11 Install front output shaft bearing retainer gasket and retaining bolts 12 Install the front output shaft flange gasket seal washer and retaining nut Tap dust shield back in place after installing bolts in flange 13 Install front output shaft rear bearing retainer gasket and retaining bolts NOTE If rear bearing was removed position new bearing to outside face of cover and press into cover until bearing is
236. aft or from damage should be corrected Check fuel pump for leaks and proper operation Correct as necessary Check operation of starter motor and solenoid Repair or replace as necessary Inspect park or neutral safety switch Adjust or replace as necessary Check operation of EFE valve as outlined in Section 6T of this manual Repair or replace as necessary Check for air or vacuum leaks Correct as necessary TRUCK SUPP SERVICE ENGINE 6 5 ENGINE LOPES WHILE IDLING a Check for vacuum leaks and correct as necessary b Check for blown head gasket and repair as necessary Inspect condition of camshaft timing chain and or sprockets Replace as necessary Check engine operating temperature and correct as necessary Check the PCV system for satisfactory operation Correct as necessary Check fuel pump for leaks and proper operation Correct as necessary Check operation of Exhaust Gas Recirculation valve Repair or replace as necessary Check ignition timing and operation of the H E I system as outlined in Section 6Y of this manual Correct as necessary i Check carburetor for incorrect idle speed defective altitude compensator sticking choke or enrichment system and adjust repair or replace as necessary j Check operation of EFE valve as outlined in Section 6T of this manual Repair or replace as necessary Check inspect and regap spark plugs Replace if
237. ain with petrolatum Fig 13B Teflon Rings REACTION CARRIER ROLLER CLUTCH AND OUTPUT CARRIER ASSEMBLY The procedure for inspection remains the same with the following addition Inspection procedure step number 1 should read 1 If the reaction carrier has a spacer ring in an undercut at the bottom of the roller cam ramps inspect it for damage Fig 14B CoI D MMH Ee eee ee RSS RE NOTE The reaction carrier with the undercut and spacer ring is used optionally and interchangeably with the reaction carrier which does not have an undercut and spacer ring REACTION CARRIER SPACER RING Fig 14B Inspecting Spacer Ring FRONT AND REAR BANDS SUPPORT TO CASE SPACER Inspection 1 Inspect lining for cracks flaking burning or looseness 2 Inspect bands for cracks or distortion 3 Inspect end for damage at anchor lugs or apply lugs 4 Inspect support to case spacer for burrs or raised edges if present remove with stone or fine abrasive CASE EXTENSION EXCEPT CL MODEL Inspection The procedure for inspection remains the same with the following exception Inspection procedure Step number 1 should read 1 Inspect bushing for excessive wear or damage If replacement is necessary remove rear seal and with extension housing properly supported remove bushing as follows a All except CA and CB Models Using Tool J 21465 17 with Dr
238. al CASE ASSEMBLY The procedure for inspection remains the same with the following addition REAR OIL BALL BEARINGS SEAL BEARING SPACER CASE EXTENSION Fig 15B Model CL Case Extension AUTOMATIC TRANSMISSION 74 11 Inspection Inspection procedure step number 4 and 5 should read 4 On model CL inspect studs for thread damage and make sure they are tight NOTE The two 2 studs at 9 o clock and 11 o clock when viewed from the rear of case and transmission in vehicle are approximately 1 4 longer than the other four 4 studs These two longer studs are required to accommodate the parking brake actuating cable bracket 5 Inspect intermediate clutch driven plate lugs for age or brinneling NOTE If the case assembly requires replacement remove the nameplate from the old case and re install it on the new case using the truss head nameplate attaching screw that is serviced with the case REAR UNIT The procedure for assembly remains the same with the following addition Assembly 11 Install reaction carrier to output carrier metal or non metal thrust washer with tabs facing down in pockets of output carrier and retain with petrolatum NOTE The production built transmissions use a non metal washer here However the service replacement washer is made of metal ASSEMBLY OF UNITS TO TRANSMISSION CASE The procedure for assembly remains the same with the following exception Assembly procedu
239. al as follows a All except CA and CL Models use a non hardening sealer on outside of seal body and using Tool J 21359 drive seal in place fig 17B b Model CL use a non hardening sealer on outside of seal body and using Tool J 24057 drive seal in place fig 17B c Model CA use a non hardening sealer on outside of seal body and using Tool J 21426 drive seal in place fig 17B CHECK BALLS CONTROL VALVE SPACER PLATE AND GASKET DETENT SOLENOID FRONT SERVO ASSEMBLY AND ELECTRICAL CONNECTOR The procedure for assembly remains the same with the following additions Assembly Assembly procedure steps number 3 and 4 should read 3 Install control valve spacer plate to case gasket gasket with extension for detent solenoid and a C near front servo location 4 Install control valve spacer plate and control valve to spacer plate gasket gasket identified with a a VB near front servo Fig 17B Installing Extension Oil Seal Typical MODULATOR VALVE AND VACUUM MODULATOR Installation 1 Install modulator valve into case stem end out 2 Install O ring seal on vacuum modulator 3 Install vacuum modulator into case NOTE Models and CZ use a modulator that is different than the modulator used on the other models Refer to parts catalog book for correct usage 4 Install modulator retainer and attaching bolt Torque bolt 18 ft Ibs CONVERTER ASSEMBLY Installation With the trans
240. all bolts Tighten bolts alternately to 144 pound inches Connect downshift cable and adjust as required Connect accelerator linkage Connect fresh air hose and choke hose to choke system Connect fuel and vacuum lines Install air cleaner Oo C Refer to Maintenance and Adjustment and check idle speed FUEL FILTER REPLACEMENT A plugged fuel filter will shut off fuel flow into carburetor Disconnect fuel line connection at inlet fuel filter nut Remove inlet fuel filter nut from carburetor Remove filter element and spring Install element spring and filter element in carburetor Q Install new gasket on inlet fitting nut and install nut in carburetor and tighten securely 6 Install fuel line and tighten connector AIR HORN TIGHTENING SEQUENCE Refer to figure 20Q for proper air horn tightening sequence Fig 20Q Air Horn Tightening Sequence TRUCK SUPP SERVICE ENGINE FUEL 6M 65 DIAGNOSIS Refer to MAMC MAME Quadrajet section of this manual for diagnosis of the 4MV Quadrajet ACCELERATOR CONTROL GENERAL of cable The accelerator control system is cable type There are no ACCELERATOR CONTROL CABLE linkage adjustments reference between the bottom of Refer to figures 1C through 4C for removal and installation accelerator pedal and floor pan should be used only as a of accelerator control cable check for bent bracket assembly Check torque references ACCEL
241. all Refer to figure 35 for proper air horn tightening sequence bolts Tighten bolts simultaneously to 145 in 18 Connect detent cable and adjust as required Connect accelerator linkage Connect fresh air hose and choke hose to choke system Connect fuel and vacuum lines Install air cleaner nunu O tA Refer to Maintenance and Adjustment and check idle speed FUEL FILTER REPLACEMENT Fig 34 A plugged fuel filter will restrict fuel flow into carburetor and will result in a loss of engine power 1 Disconnect fuel line connection at inlet fuel filter nut Remove inlet fuel filter nut from carburetor Remove filter element and spring Install element spring and filter element in carburetor Ww N Install new gasket on inlet fitting nut and install nut in carburetor and tighten securely 6 Install fuel line and tighten connector Fig 35 Air Horn Tightening Sequence TRUCK SUPP SERVICE 6M 26 ENGINE FUEL s ee DIAGNOSIS GENERAL When carburetor troubles are encountered they can usually be diagnosed and corrected with an adjustment as outlined below and under Maintenance and Adjustments Before diagnosing the carburetor as the trouble area check and diagnose the following 1 Fuel Supply 2 Fuel pump pressure and volume 3 Plugged fuel filter or fuel lines 4 Linkage and emission control systems 5 Engine compression 6 Ignition system firing voltage
242. all coil and set to proper index Fig 52 If coil is cooled off suficiently the choke valve will close when throttle is opened slightly Attach a jumper wire between the positive battery terminal and choke coil terminal Choke coil should warm up and the choke blade can be observed opening indicating a good and properly grounded choke coil assembly At room temperature the choke blade should be wide open in approximately 90 seconds If the choke does not operate properly after the coil has been proven satisfactory check out the other possibilities that prevent current from getting to the choke coil UNLOADER ADJUSTMENT Fig 53 1 Install choke thermostatic coil and cover assembly with gasket in choke housing no gasket is used on M4ME and align index mark on cover with specified point on housing see Automatic Choke Coil Adjustment Figures 51 and 52 4 GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND AIR HORN WALL 3 ON WARM ENGINE CLOSE CHOKE VALVE BY PUSHING UP ON TANG ON VACUUM BREAK LEVER HOLD IN POSITION WITH RUBBER 1 INSTALL CHOKE THERMOSTATIC COVER AND COIL ASSEMBLY IN HOUSING ALIGN INDEX MARK WITH SPECIFIED POINT ON HOUSING 5 BEND TANG TO ADJUST 2 HOLD PRIMARY THROTTLE VALVES WIDE OPEN Fig 53 Unloader Adjustment 2 With choke valve completely closed hold throttle valves wide open NOTE On warm engine close choke valve by pushing up on tang of intermediate choke lever that contacts
243. alling Input Rod and Piston Assembly into Booster Typical Whenever the booster is disassembled all seals tube inserts and bracket nut should be replaced All of these parts are included a seal kit If any of the accumulator valve components are damaged or lost replace all valve components all are included charging valve Kit Position a NEW tube seat in each booster port and screw a spare tube nut in each port to press the seat down into the port Do not tighten the tube nuts in the port as this may deface the seats Remove the spare tube nuts and check for aluminum chips in the ports Be sure that any foreign matter is removed Coat the piston bore and the piston seal with clean power steering fluid and assemble the NEW seal in the bore The lip of the seal must be toward the rear away from the master cylinder mounting flange Be sure the seal is fully seated in the housing Lubricate the input rod end NEW input rod seals and Seal Installer Tool J 24553 with clean power steering fluid Slide the seals on the tool with the lip of the cups toward the open end of the tool fig 6 Slide the tool over the input rod end and down to the second groove then slide the forward seal off the tool and into the groove Assemble the other seal in the first groove Be sure that both seals are fully seated Lubricate the piston and Piston Installing Tool J 24551 with clean power steering fluid Insert
244. alytic cJ DIVERTER VALVE Fig 1 A LR Pipe Installation C10 and 350 V8 Cal converter Refer to figures 1 and 2 for pipe installation on C10 and G10 with 350 V8 in California and light duty emissions EXHAUST did d 2 Fig 2 A I R Pipe Installation 610 and 350 V8 Cal TRUCK SUPP SERVICE EMISSION CONTROL SYSTEMS 6 3 EMISSION HOSE ROUTINGS Refer to figures 3 and 4 for emission hose routing on V8 engines EGR C YELLOW STRIP VALVE B CT AAP 2 N tay UPS EFE cen ASA PURPLE BW PURPLE STRIP C10 350 8 2 BBL STRIP Cio 350 V8 4 BBL W O 0 2 GIEANER f Dar SPARK CONTROL ac SWITCH v lt fox M CONG s gt 400 V8 W O A I R 54 Ao THROTTLE LEVER ACTUATOR V ERE CN lt C10 350 V8 4 BBL Unt RTER VALVE PURPLE STRIP C10 20 30 amp P30 454 8 CAL THROTTLE LEVER F M us 7 TO AIR _ CLEANER f f nori RETURN CK10 20 30 7 Z CONTROL VALVE a 350 400 8 CAL B T NN 7 THROTTLE RETURN P20 amp 30 350 V8 CAL T amp 20 400 V8 CAL 7 CONTROL VALVE Fig 3 Emission Hose Routings CKP TRUCK SUPP SERVICE 6 4 EMISSION CONTROL SYSTEMS EGR VALVE U STRIP ACTUATOR Hs G10 350 V8 2 BBL THROTTLE RETURN CONTROL CLEANER r Ka Sg THRO
245. and High Blower prior to discharging the system Add additional oil as indicated in Section 1A of this manual Oil Charge Compressor Replacement 1 Gravity drain oil from a new compressor Position compressor with shaft end up and drain compressor suction discharge ports compressor should gravity drain for 10 minutes Add additional oil as indicated in Section 1A of this manual When necessary to flush system with R 11 drain assembly and blow dry with air prior to the installation of a new compressor It is not necessary to drain oil from the replacement compressor The refrigerant 12 R 12 is to be slowly discharged from the system 3 Remove original compressor from vehicle gravity drain the oil from compressor as in Step 1 and determine the amount of oil drained from the original compressor Refer to the oil usage chart in the service section of this manual for proper amount of oil to be added SYSTEM PERFORMANCE EVALUATION When system performance efficiency and proper oil charge is in doubt and must be evaluated accurately it is recommended that the system be flushed with R 11 and the exact oil charge 6 ounces of 525 viscosity oil be added to the compressor prior to any further checks of the system TRUCK SUPP OVERHAUL 1 38 AIR CONDITIONING COMPRESSOR 18 19 J 8393 J 24095 J 5453 J 9459 J 25499 J 5420 J 25498 J 6084 J 8433 J 9395 4 23595 J 6271 01 20
246. and re gap or replace Check ignition point dwell condition readjust ignition points if necessary and check and reset ignition timing Clean or replace air cleaner element if dirty Check for restricted exhaust system and intake manifold for leakage make sure all vacuum hoses are connected correctly 1 Clean choke and free up linkage 2 Check choke coil rod for proper adjustment Reset to specifications Check fuel tank fuel lines and fuel pump for any fuel leakage Free up or replace as necessary 1 Check for dirt in the needle and seat Test using suction by mouth or needle seat tester If defective replace needle and seat assembly with factory matched set 2 Check for loaded float 3 Re set carburetor float as specified in carburetor overhaul section 4 14 excessive dirt is present in the carburetor bowl the carburetor should be cleaned Run engine at RPM where nozzle is feeding fuel Observe pump jet If fuel is feeding from jet check pump discharge ball for proper seating by filling cavity above ball with fuel to level of casting No leak down should occur with discharge ball in place Restake or replace leaking check ball defective spring or retainer Clean carburetor or overhaul as necessary TRUCK SUPP SERVICE 6M 30 ENGINE FUEL Problem ENGINE HESITATES ON ACCELERATION Defective accelerator pump system 1 Remove air horn and check pump cup If cracked NOTE A quick check of the pum
247. anger of being burned do not remove radiator cap while engine and radiator are hot because scalding fluid and steam will be blown out under pressure 2 Open drain cock and drain radiator 3 Disconnect upper and lower radiator hoses and transmission oil cooler lines or heater hose if equipped 4 Disconnect coolant recovery system hose 5 If shroud installed remove shroud to radiator screws and lift shroud out of lower clips and carefully hang Fig 4 Radiator Shroud G Series TAUCK SUPP SERVICE shroud over engine fan assembly to provide clearance for radiator removal 6 Remove finger guard G Series L6 engine only Remove radiator upper mounting panel retainers on G Series from radiator support Remove upper mounting pads Lift radiator out of the lower mountings and remove from vehicle Lift shroud out of vehicle if applicable Installation 1 Inspect mounting pads and mounting panel or retainers and replace as required With fan shroud positioned over fan lower radiator into lower mountings and install radiator upper mounting panel On G Series with L6 engine install finger guard Install fan shroud if so equipped Connect upper and lower radiator hoses Connect coolant recovery system hose Inspect hose clamps and all hoses Replace hoses whenever swollen checked or otherwise deteriorated Connect transmission oil cooler lines and heater hose if so equipped Remo
248. anister on vehicle with light duty emissions Disconnect fuel tank hose at vapor canister on vehicle with heavy duty emissions 4 Disconnect vacuum advance hose at distributor and plug hose 5 Start engine check timing and adjust as required 6 On engine with full vacuum advance connect vacuum advance hose otherwise leave hose disconnected and plugged 7 On vehicle with heavy duty emissions turn air conditioning ON 8 Position manual transmission in Neutral Position automatic transmission in Drive with light duty emissions or in Neutral with heavy duty emissions TURN 1 amp HEX SCREW TO ADJUST LOW IDLE G ENGINE WARM SOLENOID NOT ENERGIZED CHOKE VALVE OPEN FAST IDLE CAM FOLLOWER OFF STEPS OF CAM SET CURB IDLE TO SPECIFICATIONS TURN ASSEMBLY IN OR OUT TO ADJUST SOLENOID ENERGIZED Fig 9 Low and Curb Idle Speed Adjustment 9 Turn solenoid in or out to set curb idle speed to specified rpm 10 Disconnect electrical connector at idle stop solenoid and turn air conditioning OFF 11 Turn 1 8 hex screw located in end of solenoid body to set low idle speed to specified rpm 12 Reconnect electrical connector to solenoid and crack throttle slightly 13 Check fast idle speed referring to fast idle adjustment procedure 14 Shut off engine and remove tachometer TRUCK SUPP SERVICE 6M 8 ENGINE FUEL 15 Unplug and connect carburetor and PCV hoses at vapor canister on light duty emissions
249. ap aligned with notch in housing and secure with four latches Connect wiring harness connector to terminals on side of distributor cap Connector will fit only one way Adjust ignition timing as described in Specification Section of this manual Distributor Disassembly Figs 1 2 Remove distributor as described above Remove rotor from distributor shaft by removing two Screws Remove two advance springs weight retainer and advance weights Remove two screws holding module to housing and move module to a position where connector may be removed from B and C terminals 5 Remove wires from W and G terminals of module Remove roll pin from drive gear CAUTION Distributor gear should be supported in such a way that no damage will occur to distributor shaft while removing pin Remove gear shim and tanged washer from distributor shaft Remove any burrs that may have been caused by removal of pin 8 Remove distributor shaft from housing 10 11 12 13 Remove washer from upper end of distributor housing Remove lock ring at top of housing and remove pole piece and plate assembly and felt washer NOTE No attempt should be made to service the shaft bushings in the housing Remove vacuum advance mechanism by removing two Screws Disconnect capacitor lead and remove capacitor by removing one screw Remove wiring harness from distributor housing Assembly Fi
250. ar lubricant SAE 80W in Canada Delco Supreme No 11 3 fluids Engine oil Chassis grease meeting requirements of of GM 6031 M Engine oil Shift linkage floor shift Hood Latch assembly a Pivots and spring anchor b Release pawl Hood hinges Automatic transmission shift linkage Chassis lubrication Constant Velocity Universal Joint Automatic transmission Engine oil Engine oil Chassis grease Engine oil Engine oil Chassis grease meeting requirements of GM 6031 M GM Lubricant Part No 1050670 or grease meeting requirements of GM 6040 M DEXRON automatic transmission fluid Parking brake cables Front wheel bearings Body door hinge pins fuel door hinge tailgate hinges Chassis grease Wheel bearing lubricant GM Part No 1051344 or equivalent Engine oil Windshield washer solvent GM Optikleen washer solvent Part No 1051515 or equivalent Battery Engine coolant Mixture of water and a high quality Ethylene Glycol base type anti freeze conforming to GM Spec 1899 M Colorless odorless drinking water TRUCK SUPP SERVICE 0 18 GENERAL INFORMATION AND LUBRICATION BH En Tx L1 um AD 4 I VA i 4 4 y IE i D
251. are used in Production compressors a 1 2 size and a 5 8 size The bearings ARE interchangeable Service replacement bearings are all 1 2 Wash all parts to be re used with trichlorethylene stoddard solvent kerosene or a similar solvent Air dry parts using a source of clean dry air Compressor internal components may be identified by referring to Fig 1 and Fig 2 INTERNAL MECHANISM Gaging Operation 1 Install Compressing Fixture 1 9397 on Holding Fixture J 9396 in vise Place front cylinder half in Compressing Fixture flat side down Front cylinder half has long slot extending out from shaft hole Secure from Service parts stock four ZERO thrust races and three ZERO shoe discs Install a ZERO thrust race thrust bearing and a second ZERO thrust race on front end of compressor shaft Lubricate races and bearing with petrolatum Insert threaded end of shaft through needle bearing in front cylinder half and allow thrust race and bearing assembly to rest on hub of cylinder Now install a ZERO thrust race on rear end of compressor shaft Fig 36 so that it rests on hub of axial plate Then install thrust bearing and a second ZERO thrust race Lubricate races and bearing with petrolatum TRUCK SUPP OVERHAUL Front C ylinder Half Compressing Fixture J 9397 Fig 37 Installing FRONT Shoe Disc 6 Lubricate ball pockets of the No Piston with 525 viscosity refrigerant oil and p
252. aring Retaining Ring J 25031 1 LOCKING WASHER Fig 78 Installing Rotor and Bearing Puller Guide rotor hub to remove the bearing See Figure 81 Installation 1 Place rotor and hub assembly face down on a clean flat and firm surface Fig 83 2 Align new bearing squarely with hub bore and using pulley and bearing installer J 9481 with Universal Handle J 8092 drive bearing fully into hub The tool will apply force to outer race of bearing AIR CONDITIONING COMPRESSOR 1 31 Fig 79 Installing Rotor and Bearing Puller Fig 80 Clutch Coil and Housing Assembly Stake bearing in place with a 45 angle punch Fig 81 but do not stake too deep 045 055 inch and possibly distort the outer race of bearing Use new stake locations 120 apart Do not use old stake locations Recommended Method Press rotor and bearing assembly onto the front head of the compressor using Rotor and Bearing Assembly Installer J 25029 Fig 84 The Installer will apply force to the inner race of the rotor bearing when installing the TRUCK SUPP OVERHAUL 1 32 AIR CONDITIONING COMPRESSOR BEARING STAKE LOCATIONS Fig 81 Bearing Stake Locations assembly onto the front head Alternate method Reassemble the rotor and bearing assembly to the front head of the compressor using Rotor Bearing Remover and Rotor Assembly Installer J 25029 With Installer assembled to the Universal Handle J 8092 as shown in Fig 85 force
253. art speed must be limited to 65 mph or the tire load reduced to the tire load limit indicated in the Tire Wheel Load and Inflation Pressure Chart for 10 PSI less cold inflation pres sure For special operating conditions such as carrying slide in cam pers or other high center of gravity loads cold inflation pressures may be increased up to 10 PSI above those shown in the table with no increase in loads The total increase in cold inflation pressures shall not exceed 10 PSI above the proper pressures for the load being carried and must not exceed the wheel inflation pressure and load capacity shown on the wheel code and limits chart shown in this section 5 Always use a tire pressure gauge a pocket type gauge is recom mended when checking inflation pressures Radial tires may have the appearance of being linderinflated when at recommended cold inflation pressures PROPERLY INFLATED PROPERLY INFLATED BIAS RADIAL TIRE OR BIAS BELTED TIRE 6 Be sure to reinstall the tire inflation valve caps if so equipped to prevent dirt and moisture from entering the valve core which could cause air leakage 1710 1800 1970 2070 1970 2070 2175 2260 2360 WHEEL CODE AND LIMITS WHEEL LIMITS SIZE OF WHEEL MAX MAX LOAD LBS PRESS PSI 15 x7 JJ 15 x 8JJ 15x7 JJ 15 x 8 00 JJ 15 x6 JJ 16 5 x 6 0 15 x6 JJ 16 x 5K 15x6 JJ 16 x 5K 19 5 x 5 25 16x5 50F 16 5 x 6 0
254. assis Engine Code LD4 250 Six 125 292 Six LF5 350 2 V8 159 350 4 V8 LF4 400 4 V8 LF8 454 4 V8 TRUCK SUPP SERVICE j MFD BY GENERAL MOTORS CORPORATION GVWR GAWR REAR GAWR FRONT WL CAMPER LOADING DATA CWR DIMA DIM B INFLATION DATA FOR TIRES FURNISHED WITH VEHICLE FRONT PRESSURE PRESSURE WARRANTY VOIDED IF LOADED IN EXCESS OF RATINGS SEE OWNERS MANUAL FOR OTHER LOADING AND INFLATION DATA if Fig 1 Vehicle Identification Number and Rating Plate Information ENGINE DESIGNATION L6 250 1 V8 350 4 16 292 1 V8 305 2 V8 350 2 V8 350 4 V8 400 4 V8 454 4 DIVISION CHEVROLET T GMT D L T Q Y U 5 Y MODEL YEAR 6 1976 for all i CHASSIS TYPE C 2 WHEEL DRIVE G LIGHT DUTY FORWARD CONTROL 4 WHEEL DRIVE L LIGHT UTILITY P FORWARD CONTROL ASSEMBLY PLANT A Lakewood V GM Truck Pontiac BODY STYLE B Baltimore 5 5 Louis 2 Forward Control U Lordstown chassis only J Janesville 3 Cab chassis Cutaway Oshawa 4 Cab and pickup box 3 GMAD Detroit 5 and Panel 4 Scarborough 6 Suburban body 7 Motor Home 8 Utility Blazer Fig 2 Vehicle Identification Number e The Turbo Hydra Matic Transmission 400 Serial Number is Located on the Light Blue Plate on the Right Side of the Transmission Engines e 6 Cylinder Engine Unit Number Located on Pad at Right
255. ated in the air horn casting above the fuel in the float bowl Vapor canister purge ports are located in the throttle body casting The ports connect by a channel to a tube pressed into the throttle body casting which leads directly to the vapor canister This provides adequate purge during engine operation to remove all fuel vapors from the vapor collection canister The pump system has a raised cast in boss on the floor of the float bowl which prevents entry of dirt into the accelerator pump power valve fuel inlet passage The pump plunger head has an expander spring beneath the pump cup to maintain good pump wall contact during pump operation The end of the pump plunger stem is upset in manufacturing to provide the clipless retaining feature The pump plunger assembly may be removed from the inner lever by twisting upset end with small pliers until it breaks The service pump assembly has a grooved end and is provided with a retaining clip Alphabetical code letters cast next to the vacuum and air tubes identify all hose connections mentioned the code letters are alphabetical and should be referred to during carburetor installation on the engine The carburetor part number is stamped on the flat section of the float bowl next to the fuel inlet nut When servicing the carburetor unit refer to the Adjustment section for proper procedures and specifications TRUCK SUPP SERVICE AIR HORN ACCELERATOR PUMP ROD
256. ation Any binding condition which may have developed due to petroleum gum formation on the choke shaft or from damage should be corrected Check carburetor choke hoses for proper connection cracking abrasion or deterioration and correct or replace as necessary 3 ENGINE IDLE SPEED Adjust engine idle speed accurately following the specifications shown on the label under the hood Adjustments must be made with test equipment known to be accurate 4 EARLY FUEL EVAPORATION EFE SYSTEM Check valve for proper operation A binding condition must be corrected Check switch for proper operation Check hoses for cracking abrasion or deterioration Replace parts as necessary TRUCK SUPP SERVICE 0 16 GENERAL INFORMATION AND LUBRICATION 5 CARBURETOR MOUNTING At 7 500 22 500 and 45 000 miles for V8 engines and 7 500 30 000 for L 6 engines torque carburetor attaching bolts and or nuts to compensate for compression of the gasket C 6 VACUUM ADVANCE SYSTEM AND HOSES Check system for proper operation and hoses for proper connection cracking abrasion or deterioration Replace parts as necessary C 7 FUEL FILTER Replace filter in carburetor at designated intervals or more frequently if clogged C 8 POSITIVE CRANKCASE VENTILATION SYSTEM PCV Check the PCV system for satisfactory operation at 12 month 15 000 mile intervals and clean filter Replace the PCV valve at 24 month 30 000 mile intervals and blow out PCV val
257. ator spring aligning spring in valve Install the 1 2 modulator bushing 14 Compress bushing against spring and install retaining pin 15 Install manual valve with detent pin groove to the right FORWARD CLUTCH The procedure for disassembly inspection and assembly remains the same with the exception of these changes Disassembly a Model CA Remove four 4 radial grooved composition faced three 3 thin 0775 flat steel and one 1 waved steel clutch plates from forward clutch housing b Models CJ CM CP CT and CZ Remove five 5 radial grooved composition faced four 4 thin 0775 flat steel and one 1 waved steel clutch plates TRUCK SUPP OVERHAUL 7A 8 AUTOMATIC TRANSMISSION REGULATOR DETENT VALVE VALVE PISTON Fig 10B Installing Detent Regulator Valve and Detent Valve NOTE The production built transmissions use a direct clutch piston without a check ball The forward and direct clutch pistons look almost the same Make sure the forward clutch piston is identified during disassembly so it will be reassembled into the forward clutch housing Fig 8B Installing Compressor Tool to Front Accumulator Piston The production built forward clutch piston will be aluminum or stamped steel Assembly Assembly procedure step number 10 should read 10 Install forward clutch plates a Model CA Install one 1 waved steel plate with RETAINING RING OIL SEAL RING TEFLON
258. ays remove plug used in inlet hole after completing idle adjustment otherwise the compensator will not operate MAIN METERING SYSTEM Fig 4 The main metering system supplies fuel to the engine from off idle to wide open throttle operation It feeds at all times when air flow through the venturi is great enough to maintain efficient fuel flow from the main discharge nozzle The triple venturi stack up used in the Monojet carburetor 1s very sensitive to air flow which results in a finer and more stable metering control from light to heavy engine loads The main metering system consists of a main metering jet mechanical and vacuum operated metering rod main fuel well main well air bleeds fuel discharge nozzle and triple venturi The main metering system operates in the following manner As the throttle valve is opened beyond the off idle range allowing more air to enter the engine manifold air velocity increases in the carburetor venturi This causes a drop in pressure in the main venturi which is increased many times in the double boost venturi Since the lower pressure vacuum is now in the smallest venturi fuel flows from the main discharge nozzles in the following manner Fuel in the float bowl passes between the tapered metering rod and the main metering jet where it is metered and flows on into the main fuel well In the main well the fuel is mixed with air from the air bleed at the top of the well and another air bleed
259. be rotated by hand Back off adjustment ten notches and check drum for free rotation 5 Place parking brake lever in fully released position Take up slack in brake linkage by pulling back on cable just enough to overcome spring tension Adjust clevis of pull rod or front cable to line up with hole in relay levers a Insert clevis pin and cotter pin then tighten clevis locknut b Install a new metal hole cover in drum to prevent contamination of brake c Lower rear wheels Remove jack and wheel blocks CAUTION See Caution on Page 1 of this section PARKING BRAKE PROPELLER SHAFT INTERNAL EXPANDING Removal 1 Remove the propeller shaft see Section 4 of the 1974 Light Duty Truck Service Manual 2 Remove the brake drum NOTE It may be necessary to back off the shoe adjustment before removing the drum TRUCK SUPP SEAVICE BRAKES 5 7 C100 16 C200 C300 C100 03 amp LF8 EXC C100 03 amp F44 ya aa s 2 C100 03 amp LD4 OR 159 EXC F43 C100 03 amp LF5 OR LG9 C100 06 amp LD4 C MODELS G MODELS P MODELS Fig 4 Parking Brake System Typical TRUCK SUPP SERVICE 5 8 BRAKES P300 42 amp M40 amp JB9 Fig 5 Parking Brake System Propshaft TRUCK SUPP SERVICE On automatic transmission models the exhaust crossover pipe may be in the way If so loosen the transmission rear mounting bolts and jack the transmissi
260. bly ASSEMBLY Throttle Body 1 Install idle speed screw and spring assembly in throttle body if removed Fig 7C If it was necessary to remove the idle mixture needles install the idle mixture needles and springs into the throttle body until finger tight and seated Back out screws four turns as a preliminary idle adjustment Install new rubber dust seal into cavity inside choke housing Fig 9C Lip on seal faces towards carburetor after the housing 15 installed Install inner choke coil lever and shaft assembly into choke housing With the choke coil lever and shaft assembly installed into housing install the intermediate choke lever on flats of intermediate choke shaft and retain with screw Tighten securely Install new choke housing to carburetor gasket Position choke housing on throttle body and retain with two attaching screws Tighten securely Fig 8C Before installing the choke cover coil and baffle plate assembly refer to intermediate choke rod adjustment Service to adjust intermediate choke rod so that with the choke valve closed the lever inside the choke housing lines up with gauge Install choke thermostatic coil and cover assembly with new gaskets and end of coil below plastic tang on the inner choke housing lever Refer to automatic choke coil adjustment Service to index cover Install three choke thermostatic coil retainers and screws Tighten securely Fig 7C
261. bly the shoe with the short lining should be to the left with the lever assembled to it automatic transmission to the right manual transmission Pull brake shoes apart and install strut lever and spring between them The loop on the strut spring should be in the up position Install hold down pins washers springs and cups from flange plate to shoes Place guide plate on anchor pin Install pull back springs Remove the knock out plug if necessary and install a new metal plug in the brake drum adjusting hole Install the brake drum Install the propeller shaft TRUCK SUPP SERVICE 5 10 BRAKES o Mon e sc o wmHl M ni i canman Pp ee Le Lupe euasit aa VACUUM POWER BRAKES POWER BOOSTER REPAIR OR REPLACE CAUTION Any time the power brake vacuum booster is removed for repair or replacement be sure to install a NEW check valve HYDRO BOOST POWER BRAKES All 1976 hydro boost vehicles will incorporate accumulator which is integral with the booster fig 6 INTEGRAL ACCUMULATOR BOOSTER The booster power section includes three ports fig 6 1 Pressure Port 11 16 18 thread the high pressure line from the power steering pump is connected to this port 2 Gear Port 5 8 18 thread the high pressure line leading to the power steering gear is connected to this port 3 Return Port for 3 8 I D H
262. bowl insulator gasket Install throttle body on bowl gasket so that all holes in throttle body are aligned with holes in gasket Install two throttle body to bowl attaching screws and lockwashers Tighten even and securely to 15 ft Ibs Float Bowl l 2 Install idle stop solenoid if removed A T only Install seal into recess in idle compensator cavity in float bowl then install compensator assembly Install idle compensator cover retaining with two attaching screws Tighten securely Install main metering jet into bottom of fuel bowl Tighten securely Install needle seat and gasket Install idle tube flush with bowl casting Install pump ball spring and T into pump discharge hole Push down on pump discharge T until flush with bowl casting Fig 4 Install fuel filter spring filter inlet nut and gasket Install accelerator pump return spring 11 12 13 14 15 18 19 20 Install power piston return spring into piston cavity in the bowl Install power piston actuating rod right angle end into slot in the power piston Install piston metering rod and actuating rod assembly into the float bowl End of actuating rod must enter hole in bowl Locate metering rod into jet orifice Install pump plunger assembly into pump well with actuating lever protruding through bottom of bowl casting Push downward on pump and install pump assembly driv
263. by pushing upward on the choke coil lever inside the choke housing AIR VALVE COMPLETELY CLOSE 5 Gauge between the UPPER edge of the choke valve and inside air horn vertical wall Gauge dimension should be as specified SEAT CHOKE VACUUM DIAPHRAGM USE OUTSIDE 6 Bend adjusting tang on fast idle cam to obtain the dimension Make sure tang lays against cam after Aena HERE ROR bending AND END OF SLOT IN LEVER 7 Reinstall coil assembly into choke housing Be sure that the coil tang picks up the choke coil lever and closes the choke valve when rotating the cover LOADED PLUNGER counterclockwise MUST BE HELD INWARD AND SEATED DO NOT 8 Install the screws and retainers after indexing the coil ome SE to specifications Secure the cover to the housing at the proper index by tightening the three screws Fig 48 Air Valve Dashpot Adjustment NOTE Always check fast idle adjustment on vehicle by setting engine speed to specification listed 4 Push inside choke coil lever counterclockwise until tang underhood Vehicle Emission Control Information on vacuum break lever contacts tang on vacuum break label stem AIR VALVE DASHPOT ADJUSTMENT Fig 48 8 Holding gauge vertically place gauge between upper edge of choke valve and inside air horn wall Dimension 1 Seat front vacuum break diaphragm using outside should be as specified vacuum source 6 To obtain correct specification tu
264. can be timed for precise metering of exhaust gases to the intake manifold dependent upon location of the ports in the carburetor bore and degree of throttle valve opening As the throttle valves are opened further in the part throttle range the upper port ceases to function as an air bleed and is gradually exposed to manifold vacuum to supplement the vacuum signal at the lower port and maintain correct E G R valve position The upper and lower vacuum ports connect to a cavity in the throttle body which in turn through a passage supply the vacuum signal to an E G R tube pressed into the front corner of the throttle body casting The tube in the throttle body is connected by a hose to the E G R valve located on the intake manifold The E G R valve remains closed during periods of engine idle and deceleration to prevent rough idle which could be caused from excessive exhaust gas contamination in the idle air fuel mixtures CANISTER PURGE Fig 38 In that the fuel tank is not vented to atmosphere and fuel vapors are collected in the vapor canister a purge port is provided in the carburetor throttle body The purge port leads through passages to a common chamber in the throttle body to a purge tube which connects by a hose to the vapor canister The purge port consists of a separate timed canister purge Timed Bleed Purge The timed bleed purge port is located in each bore next to the off idle discharge ports The timed purge op
265. carburetor bore limited amount of canister purge is also provided by a separate tube which leads from the canister to the PCV valve hose connection An exhaust gas recirculation E C R system is used on all models to control oxides of nitrogen emissions The E G R valve is operated by a vacuum signal taken from the carburetor throttle body A vacuum supply tube installed in the carburetor air horn connects by a passage through the float bowl to the timed vertical port in the throttle body bore This provides a vacuum signal to the E G R valve in the off idle and part throttle operation of the carburetor The purpose of the E G R system is to supply a metered amount of exhaust gases to the combustion mixtures and lower combustion temperatures thereby reducing oxides of nitrogen during these ranges of engine operation Hot Idle Compensator The hot idle compensator Figure 3 with automatic transmission and air conditioning only is located in a chamber on the float bowl casting adjacent to the carburetor bore on the throttle lever side of the carburetor Its purpose is to offset enrichening effects caused by changes in air density and fuel vapors generated during hot engine operation The compensator consists of a thermostatically controlled valve a bi metal strip which is heat sensitive a valve holder and bracket The valve closes off an air channel which leads from a hole inside the air horn to a point below the throttle va
266. ce if necessary m Inspect mis match of oil ring expander and rail and correct as necessary TRUCK SUPP SERVICE ENGINE 6 9 NO OIL PRESSURE WHILE IDLING Check faulty oil gauge sending unit and correct as necessary Check for oil pump not functioning properly Regulator ball stuck in position by foreign material and correct as necessary c Inspect for excessive clearance at main and connecting rod bearings and correct as necessary d Inspect for loose camshaft bearings and correct as necessary e Inspect leakage at internal oil passages and correct as necessary NO OIL PRESSURE WHILE ACCELERATING Check low oil level in oil pan and correct as necessary Inspect leakage at internal oil passages and correct as necessary Check oil pump suction screen loose or fallen off and correct as necessary BURNED STICKING OR BROKEN VALVES Check for weak valve springs and replace as necessary b Check for improper valve lifter clearance and adjust as necessary Check for improper valve guide clearance and or worn valve guides and correct as necessary Check for out of round valve seats or incorrect valve seat width and correct as necessary Check for deposits on valve seats and or gum formation on stems or guides and correct as necessary Check for warped valves or faulty valve forgings and correct as necessary Check for exhaust back pressure and correct as nece
267. center screw into J 9401 remover to remove clutch plate and hub assembly Fig 71 4 Remove the shaft key Installation 1 Install shaft key into hub key groove Fig 72 Allow key to project approximately 3 16 out of keyway Shaft key is curved slightly to provide an interference fit in shaft key groove to permit key projection without falling out 2 Besure frictional surface of clutch plate and clutch rotor are clean before installing clutch plate and hub assembly 3 Align shaft key with shaft keyway and assemble clutch plate and hub assembly on compressor shaft CAUTION 7o avoid internal damage to compressor do not drive or pound on clutch hub or shaft 4 Place spacer bearing J 9480 2 on hub and insert end of clutch plate and hub assembly installer J 9480 1 through spacer J 9480 2 and thread tool onto end of compressor shaft Fig 73 5 Hold hex portion of tool body with a wrench and tighten center screw to press hub onto shaft until there is a 020 to 040 inch air gap between the frictional surfaces of clutch plate and clutch rotor Fig 6 1 25030 152506 CLUTCH ASSEMBLY J 25008 1 Fig 70 Removing Shaft Locknut 6 Install a new shaft nut with the small diameter boss of nut against crankshaft shoulder using special thin wall socket J 9399 Hold clutch plate and hub assembly with clutch hub holding tool J 25030 and tighten to 8 12 foot pounds torque COMPRESSOR SHAFT SEAL ASSEMBLY Removal
268. ch lets the choke valve open quickly As the thermostatic coil warms up to the fully hot position the choke coil lever allows the fast idle cam to drop down so that the cam follower is completely off the steps of the fast idle cam MAINTENANCE AND ADJUSTMENT IDLE SPEED ADJUSTMENT Refer to Vehicle Emission Control Information label on vehicle for latest certified specification information which may differ from specifications in manual 1 With engine at normal operating temperature air cleaner on choke open and air conditioning OFF for light duty emission vehicle or air conditioning ON for heavy duty emission vehicle except 454 engine connect a tachometer to engine 2 Set parking brake and block drive wheels 3 Disconnect vacuum advance hose at distributor and plug hose 4 Start engine check timing and adjust as required Connect vacuum advance hose 5 Position automatic transmission in Drive on light duty emission vehicle or in Neutral on heavy duty emission vehicle Position manual transmission in Neutral 6 Adjust carburetor idle speed to obtain specified rpm 7 Check fast idle speed referring to fast idle speed adjustment 8 Shut off engine and remove tachometer IDLE MIXTURE The idle mixture is factory preset and idle mixture screws are capped with plastic limiter caps The cap permits screw to be turned about one turn leaner clockwise without breaking cap The idle mixture is set to achieve the smooth
269. charge holes The idle mixture needle discharge holes provide fuel for curb engine idle As the throttle valve is opened further the off idle discharge ports are exposed to manifold vacuum These ports supply additional fuel mixture for off idle engine requirements The fuel vapor collection canister is purged by ports located in the carburetor throttle body Timed purge ports are connected from the carburetor bore to a common tube pressed into the throttle body casting The tube connects directly to the vapor canister through a hose Timed purge ports one in each bore located above the throttle valve near FILTER LARGE INTERNAL RELIEF BOWL VENT HOLE SPRING FUEL INLET FITTING Fig 21 Float System the off idle discharge ports purge the canister during off idle and part throttle ranges of operation An Exhaust Gas Recirculation system is used to control oxides of nitrogen A vacuum supply tube located just beneath the spark tube on the float bowl connects by a channel to purge ports located just above the throttle valve in the throttle body bore As the throttle valve is opened beyond the idle position the E G R ports are exposed to manifold vacuum which supplies a signal to the diaphragm in the E G R valve The two ports located in the throttle body bore are timed to provide just the right amount of vacuum to the E G R valve diaphragm to control exhaust gases introduced into the intake manifold air fue
270. closing the choke valve along with tension from the choke thermostatic coil for improved cold starting The choke closing assist spring only exerts pressure on the vacuum break rod to assist in closing the choke valve during engine starting When the engine starts and the choke vacuum diaphragm seats the closing spring retainer hits a stop on the plunger stem and no longer exerts pressure on the vacuum break rod A clean air purge feature is used on the vacuum break unit The purpose of the clean air purge is to bleed air into the vacuum break passage and purge the system of any fuel vapors or dirt which might contaminate and plug the check valve located inside the diaphragm unit The purge system TRUCK SUPP SERVICE 6M 22 ENGINE FUEL consists of a small bleed hole located in the end cover of the vacuum break diaphragm A ball check is encased in the vacuum inlet tube The ball seats when backfiring occurs to prevent contamination of filter Under normal engine operation the ball is pulled off its seat by manifold vacuum During engine operation vacuum acting upon the diaphragm unit pulls a small amount of filtered air through the bleed hole to purge the system Engine vacuum supplied through an orifice in the choke housing pulls heat from the manifold heat stove into the housing and gradually relaxes coil tension which allows the choke valve to continue opening through inlet air pressure pushing on the off set choke valve
271. combustible mixture so that the engine will start TRUCK SUPP SERVICE 6M 60 ENGINE FUEL MAINTENANCE AND ADJUSTMENT IDLE SPEED ADJUSTMENT The carburetor idle speed screw is used for adjusting curb idle speed according to specifications listed on the Vehicle Emission Control Information label on the vehicle 1 With engine at normal operating temperature air cleaner on choke open and air conditioning off connect a tachometer to the engine 2 Set parking brake and block drive wheels 3 Disconnect fuel tank hose from vapor canister on California vehicle 4 Disconnect and plug vacuum advance hose at distributor Set ignition timing at specified rpm Unplug and reconnect vacuum advance hose at distributor 5 Place transmission in Park or Neutral and on 350 400 V8 turn ON 6 Turn carburetor idle speed screw to obtain specified rpm 7 Check fast idle speed referring to fast idle adjustment 8 Shut off engine and remove tachometer 9 Connect fuel tank hose to vapor canister IDLE MIXTURE ADJUSTMENT The idle mixture 18 factory preset and idle mixture screws are capped with plastic limiter caps The cap permits screw to be turned about one turn leaner clockwise without breaking cap The idle mixture is set to achieve the smoothest idle while maintaining emission levels within standards prescribed by Federal Law At major carburetor overhaul the idle mixture may be adjusted Before susp
272. cond Third synchronizer assembly with flat portion of synchronizer hub facing rearward on output shaft Rotate Second gear until notches in blocking ring engages keys in Second Third synchronizer assembly NOTE It may be necessary to tap synchronizer with a plastic hammer to ease assembly 8 Install retaining snap ring on output shaft and measure end play between snap ring and Second Third synchronizer hub with feeler gauge fig 20R End play TRUCK SUPP OVERHAUL 7M 8 MANUAL TRANSMISSION SECOND GEAR BLOCKING RING Fig 19R Installing Second Gear Fig 20R Measuring Output Shaft End Play should be 0 004 to 0 0014 inch If end play exceeds 0 014 inch replace thrust washer and all snap rings on output shaft assembly ASSEMBLY OF TRANSMISSION 1 Coat transmission case reverse idler gear thrust washer surfaces with Vaseline or equivalent and position thrust washer in case NOTE Be sure to engage locating tabs on thrust washers in locating slots in case 2 Install reverse idler gear with helical cut gear towards front of case Align gear bore thrust washers case bores and install reverse idler gear shaft from rear of case NOTE Be sure to align and seat roll pin in shaft into counterbore in rear of case 3 Measure reverse idler gear end play by inserting feeler gauge between thrust washer and gear End play should be 0 004 to 0 018 inch If end play exceeds 0 018 inch remove idler gear and
273. cular projection on the locknut facing towards retainer ring Tighten the nut to 14 26 Ib ft torque Air gap between the frictional faces should now be 022 to 057 Fig 9 If not check for mispositioned key or shaft 7 The pulley should now rotate freely 8 Operate the refrigeration system under MAXimum load conditions and engine speed at 2000 RPM Rapidly cycle the clutch by turning the air conditioning on and off at least 15 times at approximately one second intervals to burnish the mating parts of the clutch PULLEY AND BEARING ASSEMBLY Remove 1 Remove clutch plate and hub assembly as described in Compressor Clutch Plate and Hub Asm Removal procedure 2 Remove pulley retainer ring using Snap Ring Pliers J 6435 26 Fig 10 3 Pry out absorbent sleeve retainer and remove absorbent sleeve from compressor neck 4 Place Puller Pilot J 9395 over end of compressor shaft CAUTION 4 is important that Puller Pilot J 9395 be used to prevent internal damage to compressor when removing pulley Under no circumstances should Puller be used DIRECTLY against drilled end of shaft 5 Remove Pulley and Bearing Assembly using Pulley Puller J 8433 Fig 11 Inspection Check the appearance of the pulley and bearing assembly See Fig 6 The frictional surfaces of the pulley and bearing assembly should be cleaned with a suitable solvent before reinstallation TRUCK SUPP OVERHAUL DRIVEN PLATE AIR CONDITION
274. cuum pull on the power piston and the tapered primary metering rod tip moves upward in the main metering jet orifice This smaller diameter of the metering rod tip allows more fuel to pass through the main metering jet and enrich the mixture flowing into the primary main wells and out the main discharge nozzles When manifold vacuum rises and mixture enrichment is no longer needed the vacuum overcomes the power piston spring tension and returns the larger portion of the metering rod into the metering jet orifice and back to normal economy ENGINE FUEL 6M 57 SECONDARY BAFFLE wan accruenaron WELL TUBE METERING ROD LEVER MAIN METERING RODS 2 POWER PISTON ECCENTRIC CAM DISCHARGE NOZZLE E FUEL WELL METERING MANIFOLD ORIFICE vacuum SECONDARY PLATES METERING RODS 12 SECONDARY THROTTLE VALVE Fig 5Q Power System ranges However as the engine speed and load increases further the primary side of the carburetor can no longer meet the engine air and fuel requirements When the engine reaches a point where the primary bores cannot meet engine air and fuel demands the primary throttle lever working through connecting linkage to the secondary throttle shaft lever begins to open the secondary throttle valves As air flows through the secondary bores creating a low pressure vacuum beneath the air valve atmospheric pressure on top of the air valve forces the air valve op
275. cylinder distributors install tanged washer shim and drive gear on distributor shaft On 6 cylinder distributors install drive gear distributor shaft Align holes of drive gear with hole of distributor shaft so that locating mark on drive gear is in line with tip of rotor Support distributor shaft on a wooden block or other suitable object and install roll pin Make sure distributor is supported in such a way that no damage will occur to distributor shaft while installing roll pin Fig 9i Roll Pin Installation ENGINE ELECTRICAL 6Y 15 14 Check to make sure shaft is not binding by spinning shaft a few times by hand 15 Install distributor as described previously in this section Ignition Coil 8 Cylinder Removal Fig 10i 1 Disconnect battery wire and harness connector from distributor cap 2 Remove three screws securing coil cover to distributor cap 3 Remove four screws securing ignition coil to distributor cap 4 Remove ground wire from coil 5 Push coil leads from under side of connectors and remove coil from distributor cap Installation Fig 10i 1 Position coil into distributor cap with terminals over connector at side of cap 2 Push coil lead wires into connector on side of cap as follows black ground in center brown next to vacuum advance unit pink opposite vacuum advance unit 3 Secure ignition coil with four screws Place ground wire under coil mounting screw 4
276. d 2 Inspect choke thermostatic coil for proper operation Replace and adjust as required 1 Remove fuel line at carburetor Connect hose to fuel line and rum into metal container Remove the high tension coil wire from center tower on distributor cap and ground Crank over engine if there is no fuel discharge from the fuel line check for kinked or bent lines Disconnect fuel line at tank and blow out with air hose reconnect line and check again for fuel dis charge If none replace fuel pump Check pump for adequate flow as outlined in service manual 2 If fuel supply is o k check the following a Inspect fuel filter If plugged replace b If filter is remove air horn and check for a bind in the float mechanism or a sticking float needle If o k adjust float as specified in carburetor overhaul section Check proper carburetor unloading procedure Depress the accelerator to the floor and check the carburetor to de termine if the choke valve is opening If not adjust the throttle linkage and unloader as specified NOTE Before removing the carburetor air horn use the following procedure which may eliminate the flooding 1 Remove the fuel line at the carburetor and plug Crank and run the engine until the fuel bowl runs dry Turn off the engine and connect fuel line Then re start and run engine This will usually flush dirt past the carbu retor float needle and seat 2 If dirt is in fuel system clean t
277. d non California 454 V8 vehicles of 6 000 pound gross vehicle weight G V W and above use the 4MV qudrajet carburetor The 4MV model Quadrajet carburetor Figure 1Q is a two stage carburetor of downdraft design The primary fuel inlet side uses the triple venturi system with 1 7 32 venturi with small 1 3 8 throttle valve bores The triple venturi stack up plus the smaller primary bores give excellent fuel control in the idle and economy stages of operation Fuel metering in the primary side is accomplished with metering rods operating in metering jets positioned by a power piston responsive to manifold vacuum The secondary side has two large bores 2 1 4 to supplement air and fuel flow from the primary bores Using the air valve principle in the secondary side fuel is metered in direct proportion to the air passing through the secondary bores The carburetor part number is stamped on a vertical section of the float bowl near the secondary throttle lever The primary side of the carburetor has six systems of operation They are float idle main metering power pump and choke The secondary side has one metering system which supplements the primary main metering system and receives fuel from a common float chamber TRUCK SUPP SERVICE CHOKE VALVE vt FUEL INLET IDLE MIXTURE SCREW ENGINE FUEL 6 55 ACCELERATOR PUMP ROD AIR VALVE PEE SECONDARY PE THROTTLE LEVER PRIMARY THROTTLE l LEVER
278. d Cables TRUCK SUPP SERVICE SECTION 1A HEATER AND AIR CONDITIONING CONTENTS OF THIS SECTION General Information Air Conditioning GENERAL INFORMATION Refer to the 1974 Light Duty Truck Service Manual for servicing the standard heater and auxiliary heater except as follows AUXILIARY HEATER WIRING DIAGRAM Refer to section 12 of this manual for auxiliary heater wiring diagram AIR CONDITIONING Refer to the 1974 Light Duty Truck Service Manual for servicing an air conditioning system with a V8 engine or six cylinder engine except as follows MAIN UNITS OF THE SYSTEM AXIAL SIX CYLINDER COMPRESSOR Fig 1 Teflon Piston Ring Type Pistons Axial six cylinder compressors used on 1975 and 1976 vehicles are equipped with a Teflon ring type piston Fig 2 instead of the former Carbon ring type The basic compressor mechanism remains unchanged The Teflon ring type piston is dimensionally the same as the carbon ring type except for the ring groove detail The replacement procedure for the Teflon ring type piston differs from that of the carbon ring type Refer to the Overhaul section of this manual for the proper method of replacing the Teflon ring type pistons or Teflon piston rings RADIAL FOUR CYLINDER COMPRESSOR A radial four cylinder compressor Fig 3 is used on a vehicle with a six cylinder engine The compressor is mounted to the engine by mounting bracke
279. d block drive wheels 3 Connect tachometer start and warm up engine to operating temperature 4 Position transmission in PARK or NEUTRAL PLACE CAM FOLLOWER ON PROPER STEP OF FAST IDLE CAM PER UNDERHOOD TUNE UP LABEL 2 TURN FAST IDLE SCREW TO PROPER RPM S PER SPEC ON UNDERHOOD TUNE UP LABEL Fig 9Q Fast Idle Adjustment 5 Place cam follower lever on highest step of fast idle cam 6 On California 454 V8 engine plug vacuum hose at EGR valve 7 Observe fast idle speed and if necessary turn fast idle screw to obtain specified fast idle rpm Return engine to normal idle 8 Shut off engine and remove tachometer CHOKE ROD FAST IDLE CAM ADJUSTMENT FIG 10Q 1 Make fast idle adjustment TRUCK SUPP SERVICE 2 Position cam follower lever on second step of fast idle cam held firmly against rise of high step 3 Rotate choke valve toward closed position by pushing upward on vacuum break lever 4 Place specified gauge between upper edge of choke valve and inside air horn wall 5 If choke valve opening is incorrect bend choke rod to obtain gauge dimension opening 6 Recheck fast idle adjustment and adjust if required PUMP ROD ADJUSTMENT FIG 110 1 Check primary throttle valves to be sure they are completely closed 2 With pump rod in inner hole of pump lever gauge from top of choke valve wall next to vent stack to top of pump stem GAUGE BETWEEN WALL AND UPPER EDGE OF CHOKE
280. d choke shaft from air horn The choke valve screws are held in place by Loctite or equivalent so it will be necessary to restake or use Loctite or equivalent during assembly 2 No further disassembly of the air horn is necessary The pressure relief valve disc need not be removed from the top of the air horn for cleaning purposes Float Bowl Fig 3 1 Remove air horn to float bowl gasket Gasket is slit next to metering rod lever so that it can be slid over lever for ease in removal 2 Remove float assembly from float bowl by lifting upward on float hinge pin Remove hinge pin from float arm Fig 4 3 Remove float needle from seat 4 Disconnect accelerator pump and power piston actuator lever from end of throttle shaft by removing lever attaching screw Fig 4 5 Hold down on power piston while removing lever Power piston spring and metering rod assembly may now be removed from float bowl Fig 4 6 Remove lower end of power piston link from actuator lever by rotating until tang on rod slides out of notch FUEL METERING ROD IDLE MIXTURE SCREW AND LIMITER CAP Fig 3 Float Bowl Assembly TRUCK SUPP OVERHAUL ACCELERATOR PUMP PLUNGER IDLE MAIN WELL TUBE BLEED Fig 4 Float and Accelerator Pump in lever 7 Remove actuator lever from lower end of accelerator pump link in same manner 8 Push down on accelerator pump and remove actuator link by rotating until tang on rod is aligned w
281. d in carburetor overhaul section Check proper carburetor unloading procedure Depress the accelerator to the floor and check the carburetor to de termine if the choke valve is opening If not adjust the throttle linkage and unloader as specified NOTE Before removing the carburetor air horn use the following procedure which may eliminate the flooding 1 Remove the fuel line at the carburetor and plug Crank and run the engine until the fuel bow runs dry Turn off the engine and connect fuel line Then re start and run engine This will usually flush dirt past the carbu retor float needle and seat 2 If dirt is in fuel system clean the system and replace fuel filter as necessary If excessive dirt is found re move the carburetor unit Disassemble and clean 3 Check float needle and seat for proper seal If a needle and seat tester is not available apply mouth suction to the needle seat with needle installed If the needle is defective replace with a factory matched set 4 Check float for being loaded with fuel bent float hanger or binds in the float arm NOTE Check float for fuel absorption by lightly squeezing between fingers 11 wetness appears on surface or float feels heavy Check with known good float replace the float assembly 5 Adiust float as specified in carburetor overhaul section TRUCK SUPP SERVICE Problem Engine does not have enough fast idle speed when cold Choke vacuum break unit
282. d position of the washers 2 Install a new thrust washer on compressor shaft with thrust washer tang pointing up Fig 88 3 Install the new belleville washer on shaft with the high center of the washer up Fig 88 4 Install the remaining thrust washer on shaft with the NE THRUST AND tang pointing down Fig 88 BELLEVILLE WASHERS 5 Lubricate the three washers with clean oil 525 Viscosity and assemble front head to cylinder MAIN BEARING REPLACEMENT Removal Fig 87 Installing Front Head 2 Align new bearing and bearing installer J 24895 squarely with bearing bore of front head and drive 1 Remove front head assembly bearing into front head Fig 90 The tool J 24895 must 2 Place front head assembly on two blocks Fig 89 and using main bearing remover J 24896 drive bearing out seat against front head to insert bearing to proper of front head clearance depth Installation 1 Place front head with neck end down on a flat solid 3 Assemble front head to cylinder and complete the surface assembly TRUCK SUPP OVERHAUL am Fig 89 Removing Main Bearing COMPRESSOR SHELL CYLINDER RING AND VALVE PLATE REPLACEMENT The clutch plate and hub assembly the clutch rotor and bearing assembly the clutch coil and pulley rim must be removed before compressor shell can be removed or replaced The location of clutch coil terminals should be marked for reference on reassembly Allow compressor
283. d then sloped it may require that different readings be used immediately pull locking handle rearward until it locks for each side of the vehicle In this instance determine in place Headlamp aimers must always be used in pairs the floor level for BOTH sides of the vehicle It is then and installed so that they face each other fig 6 necessary to set the floor slope offset dial of EACH HORIZONTAL DIAL VERTICAL DIAL FLOOR SLOPE DIAI VERTICAL KNOB HORIZONTAL KNOB VIEWING PORT LEVEL LOCKING HANDLE AIMER J 25300 2 SHOWN AIMER J 25300 1 SIMILAR Fig 3 Headlamp Aimer TRUCK SUPP SERVICE RIGHT SIDE SHOWN 10 11 12 13 14 15 AIMER J 25300 2 AIMER J 25300 1 VIEWING PORT SIGHT OPENING 4 AIMER J 25300 1 ELECTRICAL BODY AND CHASSIS 12 3 AIMER J 25300 2 FLOOR SLOPE ADAPTER J 25300 6 RIGHT SIDE SHOWN LEFT SIDE J 25300 2 GOES IN REAR AND J 25300 1 IN FRONT Fig 4 Floor Slope Adjustment Typical Check to make sure floor slope dials of the aimers obtained in step 5 has not been disturbed Make sure horizontal dial is at zero Look into top sight opening of the aimer to see that the split image target lines are visible in the viewing port If necessary rotate each aimer slightly to locate target Turn horizontal adjusting screw of headlamp fig 1 until split image of target line appears in sight opening as one solid line To remove backlash make
284. delivery trucks etc Extensive idling Short trip operation at freezing temperatures engine not thoroughly warmed up e Operation in dust storms may require an immediate oil change e Replace the oil filter at the first oil change and every second oil change thereafter AC oil filters or equivalent provide excellent engine protection The above recommendations apply to the first change as well as subsequent oil changes The oil change interval for the engine is based on the use of SE oils and quality oil filters Oil change intervals longer than those listed above will seriously reduce engine and may affect the manufacturer s obligation under the provisions of the New Vehicle Warranty A high quality SE oil was installed in the engine at the factory It is not necessary to change this factory installed oil prior to the recommended normal change period However check the oil level more frequently during the break in period since higher oil consumption is normal until the piston rings become seated NOTE Non detergent and other low quality oils are specifically not recommended Oil Filter Type and Capacity e Throwaway type 1 quart U S measure 75 quart Imperial measure e 250 cu in 292 cu Type PF 25 350 cu in 454 cu AC Type PF 35 Crankcase Capacity Does Not Include Filter e 292 L6 Engine 5 quarts U S measure 4 25 quarts Imperial measure e All other engines 4 quarts U S m
285. derhood lamp front and rear A C circuits C K models tWhen incorporated by body builder Do not use fuses of higher amperage than those recommended above The following wiring harnesses are protected by a fusible link which is a special wire incorporated in the circuit headlamp hi beam indicator horn and ignition circuits C K P models starter solenoid pull in and hold circuit C K models Should an electrical over load occur this wire will fail and prevent damage to the major harness G TRUCK TREE 25 amp Stop Solenoid Cruise Control Directional Signal Lamp Directional Signal Indicator Lamp Transmis sion Downshift M40 sss 10 amp Cigarette Lighter Dome Lamp Spot Lamp 15 amp Fuel Gauge Brake Warning Lamp Temperature Warn ing Lamp Generator Warning Lamp Oil Pressure Warning ESI aee beo EE a Pr ena 3 amp Stop Lamp Traffic Hazard 15 amp Auxiliary Battery Backing Lamp Radio Dial Lamp Radio Qhata ha eie istos e odas 15 amp Instrument Cluster Lamp Heater Dial Lamp Transmis sion Control Lamp with Tilt Wheel Cruise Control Lamp W S Wiper Switch Lamp Headlamp Buzzer 3 amp License Lamp Parking Lamp Side Marker Lamp Tail LIME corned e IN qeSepDme eim 15 amp Windshield Wiper etes et ee ese P 25 amp An in Line fuse is located in the Ammeter and the auxiliary heater circuits
286. distributor shaft Repair or replace as necessary Check inspect and regap spark plugs Replace as necessary Check carburetor for incorrect and or misadjusted idle speed float level leaking needle and seat air valve and sticking choke or enrichment system Adjust repair or replace as necessary Inspect carburetor fuel filter for presence of water and or impurities Correct as necessary Check fuel pump for leaks and proper operation Correct as necessary Check for sticking valves weak valve springs incorrect valve timing lifter noise and worn camshaft lobes Adjust repair or replace as necessary i Check for insufficient piston to bore clearance Correct as necessary j Check condition of cylinders for uneven compression and or blown head gasket Repair as necessary k Check power steering flow control valve operation Repair or replace as necessary 1 Check for clutch slippage vehicles with manual transmissions and adjust or replace as necessary m Check hydraulic brake system for proper operation Correct as necessary n Check engine operating temperature Correct as necessary Check pressure regulator valve automatic transmission for proper operation Repair as necessary p Check transmission fluid level Correct as necessary q Loss of power may be caused by using sub standard fuel Correct as necessary r Check operation of EFE valve as outlined in Section 6T of this ma
287. down through the main metering jets into the main fuel wells It is picked up in the main wells by the two idle tubes one for each bore which extend into the wells The fuel is metered at the lower tip of each idle tube and passes up through the tube The fuel is mixed with air at the top of each idle tube through an idle air bleed Then the fuel mixture crosses over to the idle down channels where it is mixed with air at the side idle bleed located just above the idle channel restriction The mixture continues down through the calibrated idle channel restrictions past the lower idle air bleeds and off idle discharge ports where it is further mixed with air The air fuel mixture moves down to the idle mixture needle discharge holes where it enters the carburetor bores and blends with the air passing the slightly open throttle valves The combustible air fuel mixture then passes through the intake manifold to the ENGINE FUEL 6M 33 engine cylinders The idle mixture needles are adjusted at the factory to blend the correct amount of fuel mixture from the idle system with the air entering the engine at idle Turning the idle mixture needles inward clockwise decreases the idle fuel discharge and turning the mixture needles outward counter clockwise enriches the engine idle mixture Idle mixture needles are adjusted at the factory and then limiter caps are installed to discourage idle mixture needle readjustment in the field M4MC
288. e groove near the end of the pedal rod and from the groove inside the input rod end With a small screwdriver pry the plastic guide out of the output push rod retainer Disengage the tabs of the spring retainer from the ledge inside the opening near the master cylinder mounting flange of the booster Remove the retainer and the piston return spring from the opening Pull straight out on the output push rod to remove the push rod and push rod retainer from inside the booster piston Press in on spool plug and using a small screwdriver remove the snap ring from the housing bore Use pliers to remove the spool plug from the bore Remove the O ring seal from the plug discard the O ring Remove the spool spring from the bore Place the booster cover in a vise equipped with soft jawed devices Using special socket J 25085 remove the five screws that secure the booster housing to the cover Remove the booster assembly from the vise and while holding the unit over a pan separate the cover from the housing Remove the large seal ring from the groove in the cover discard the seal Remove the input rod and piston assembly and the spool assembly from the booster housing TRUCK SUPP OVERHAUL BRAKES 5 3 28 27 26 25 24 23 ID ME 9 10 FX 766413 12 Pedal Push Rod Plunger Seat Output Push Rod Pedal Rod Retainer O Ring Seal Push Rod Retainer Boot Plunger Spool
289. e Propeller Shaft Slip Joint 7 500 Miles Chassis Lubricant Rear Axle 7 500 Miles As required Check See Lubrication section Fig 7 Lubrication Conventional Models Light Duty Emission Systems gt NI TRUCK SUPP SERVICE 0 20 GENERAL INFORMATION AND LUBRICATION Lubrication Points Control Arm Bushings and Ball Joints Lubrication Period 7 500 Miles Chassis Lubricant 12 places as required Type of Fig 8 Lubrication 1 2 Ton G Models Tie Rod Ends 7 500 Miles Chassis Lubricant 4 places as required 2 fittings each side Wheel Bearings 30 000 Miles Whl Brg Lubricant 2 places as required Steering Gear 30 000 Miles BEEN Clutch Cross Shaft 7 500 Miles Chassis Lubricant As required Trans Control Shaft 7 500 Miles Chassis Lubricant As required Air Cleaner Element 30 000 Miles See Vehicle Maintenance Schedule Transmission Manual 7 500 Miles GL 5 As required See Lubrication Section Automatic 7 500 Miles or Equivalent As required See Lubrication Section 9 Rear Axle 7 500 Miles GL 5 As required See Lubrication Section 10 Oil Filter Every Second Oil Change Brake Master Cylinder 7 500 Miles Delco Supreme As required Check Add fluid when No 11 or DOT 3 fluids necessary Parking Brake Linkage 7 500 Miles Chassis Lubricant Lubricate Linkage an
290. e Chart in Fig 41 22 Remove nuts from top plate of Compressing Fixture J 9397 and remove top plate Fig 43 Gaging Rear Thrust Race 23 Separate cylinder halves while unit is in Fixture It may be necessary to use a wood block and mallet or 090 race Place thrust race in right hand slot at bottom center of Parts Tray J 9402 24 Remove rear cylinder half and carefully remove one piston at a time from axial plate and front cylinder Fifteen 15 thrust races are provided in increments of half DO NOT LOSE THE RELATIONSHIP of the 0005 one half thousandths thickness and one ZERO front ball and shoe disc and rear ball Transfer each gage thickness providing a total of 16 sizes available for piston ball and shoe disc to its proper place in Parts TRUCK SUPP OVERHAUL 0 tt M M HE H 1 18 AIR CONDITIONING COMPRESSOR 25 Tray J 9402 Remove rear outer ZERO thrust race from shaft and install thrust race just selected The ZERO thrust race may be put aside for re use in additional gaging or rebuilding operations A 6 Teflon Piston Ring Replacement The Teflon piston ring installing sizing and gaging tools are shown in Fig 45 l Remove the old piston rings by CAREFULLY slicing through the ring with a knife or sharp instrument holding the blade almost flat with the piston surface Be careful not to damage the aluminum piston OR piston groove in cutting to remove the ring WARNING
291. e Disc Thrust Bearing Teflon Ring Type Piston Teflon Piston Ring Shaft Dowel Pins f T 26 Discharge Crossover Tube O Ring 3 Thrust Races Bushing Front Suction Reed Front Discharge Valve Plate Assembly TEFLON RING Fig 2 Teflon Ring Type Piston Clutch Coil The clutch coil is molded into the steel coil housing and must be replaced as a complete assembly Three protrusions on the rear of the housing fit into alignment holes in the compressor front head The coil is secured to the front head by a pressed fit between the coil housing and neck portion of the front head The coil has 3 65 ohms resistance at 80 F ambient and will require no more than 3 2 amperes at 12 volts D C The clutch coil has two terminals for the power and ground leads Clutch Pulley The movable part of the clutch drive plate is in front of and adjacent to the rotor and bearing assembly The armature plate the movable member is attached to the drive hub through driver springs riveted to both members The hub of the drive plate is pressed on the compressor shaft and keyed to the shaft by a square drive key A self locking nut threads on the end of the shaft and is tightened against the shaft The rotor and hub is a welded assembly and contains six threaded holes for mounting the pulley rim The pulley rim is secured to the rear portion of the rotor by six screws and six special lock washers A two row ball bear
292. e amount and level of the fuel in the carburetor float bowl Higher than specified fuel levels can cause flooding hard hot starting rich fuel mixtures causing poor economy nozzle drip at idle and stalling Therefore it is important that the float be set to recommended specifications The float system on the Monojet carburetor is located adjacent to the main venturi It is designed so that angular maneuvers such as steep hills and sharp turns will not affect proper operation by keeping an adequate supply of fuel in the bowl at all times The float system consists of the following a fuel inlet filter and pressure relief spring a solid single pontoon float made of special lightweight plastic a conventional needle and seat and a float hinge pin The float hinge pin fits in dual slots cast in the float bowl and is held in place by compression of the air horn gasket against the upper loop of the hinge pin The float operates as follows fuel from the engine fuel pump is forced through the paper fuel inlet filter located behind the fuel inlet nut passes from the filter chamber up through the float needle seat and spills into the float bowl as the float bowl fills with fuel it lifts the float pontoon upward until the correct fuel level is reached in the float bowl At this point the float arm forces the float needle against the float needle seat shutting off fuel flow As fuel is used from the float bowl the float drops downward allowing
293. e and install clamp around filler tube modulator pipe and detent downshift cable Locate clamp approximately 2 inches above filler tube bracket 4 Pass cable through bracket and engage locking tabs of snap lock on bracket 5 Connect cable to carburetor lever Adjustment With snap lock disengaged position carburetor to wide open throttle W O T position and push snap lock downward until top is flush with rest of cable TRUCK SUPP SERVICE AUTOMATIC TRANSMISSION 7 3 V 8 ENGINE SNAP LOCK L 6 ENGINE CAUTION Flexible components hoses wires conduits etc must not be routed within 2 inches of moving parts of accelerator linkage forward of the Bracket unless routing is positively controlled Fig 3G Detent Downshift Cable G Series MANUAL SHAFT RANGE SELECTOR INNER yoke on transmission output shaft It is essential that LEVER AND PARKING LINKAGE ASSEMBLIES the went h le is nor obstructed TRANSMISSION REPLACEMENT The procedure for removal and installation remains the same with the addition of this notation The procedure for transmission replacement remains the NOTE Bolo provellerchate Usate lubricate splines of the transmission yoke with a NOTE If necessary the catalytic converter may have Lithium soap base lubricant The lubricant should seep to be disconnected to provide adequate clearance for from the vent hole rear cap of yoke when installing transmission remo
294. e carburetor air horn use the following procedure which may eliminate the flooding 1 Remove the fuel line at the carburetor and plug Crank and run the engine until the fuel bowl runs dry Turn off the engine and connect fuel line Then re start and run engine This will usually flush dirt past the carbu retor float needle and seat 2 If dirt is in fuel system clean the system and replace fuel filter as necessary f excessive dirt is found re move the carburetor unit Disassemble and clean 3 Check float needle and seat for proper seal If a needle and seat tester is not available apply mouth suction to the needle seat with needle installed 1f the needle is defective replace with a factory matched set 4 Check float for being loaded with fuel bent float hanger or binds in the float arm NOTE Check float for fuel absorption by lightly squeezing between fingers If wetness appears on surface or float feels heavy Check with known good float replace the float assembly 5 Adjust float as specified in carburetor overhaul section TRUCK SUPP SERVICE r W ar Ts r wr 6M 52 ENGINE FUEL NO POWER ON HEAVY ACCELERATION Problem OR AT HIGH SPEED POSSIBLE CAUSE CORRECTIVE ACTION Carburetor throttle valve not going wide open Check Lubricate throttle linkage to obtain wide open throttle in by pushing accelerator pedal to floor carburetor Dirty or plugged fuel filter Replace with a new filter element
295. e clamped in a vise with shaft end of compressor in a vertical horizontal or down position for service depending on service to be performed TRUCK SUPP OVERHAUL Screw locking Washer Pulley Rim Coil and Housing Assy Rotor Bearing Rotor and Bearing Assy Retaining Ring Clutch Drive Assy Clutch Hub Key Shaft Nut Cap Retaining Ring Superheat Switch O Ring Pressure Relief Valve O Ring Screw Shipping Plate O Ring Retaining Ring Valve Plate Assy Cylinder and Shaft Assy Thrust Washer AIR CONDITIONING COMPRESSOR 1 27 7 8 35 i 10 x 6 Belleville Washer O Ring Shell Assy Ring Seal Main Bearing Front Head Assy Screw and Washer Assy O Ring Shaft Seal Seal Seat Retaining Ring Fig 68 Radial Four Cylinder Compressor Exploded View TRUCK SUPP OVERHAUL 1 28 AIR CONDITIONING COMPRESSOR DISCHARGE SUCTION PORT PORT SUPERHEAT HIGH PRESSURE RELIEF VALVE Fig 69 Installing Holding Fixture COMPRESSOR CLUTCH PLATE AND HUB ASSEMBLY Removal 1 Attach compressor to holding fixture J 25008 1 Fig 69 and clamp fixture in a vise 2 Keeping clutch hub from turning with clutch hub holding tool J 25030 remove and discard shaft nut using Thin Wall Socket J 9399 Fig 70 3 Thread clutch plate and hub assembly remover J 9401 into hub Hold body of tool with a wrench and turn
296. e fast idle cam so the high step is in line with the fast idle cam follower on the throttle lever As the throttle is released the fast idle cam follower comes to rest on the high step of the fast idle cam thus providing enough throttle valve opening to keep the engine running after cold start During cranking engine vacuum below the choke valve pulls fuel from the idle circuit main discharge nozzle This provides adequate enrichment for good cold starts When the engine starts manifold vacuum is transmitted through a vacuum channel to the primary vacuum break diaphragm unit mounted on the air horn casting This moves the diaphragm plunger until it strikes the cover which in turn opens the choke valve to a point where the engine will run without loading or stalling This is called the vacuum break position The auxiliary vacuum break unit Fig 8 is used to open the choke valve to a nearly wide open position during warmer temperatures above 80 F This prevents too rich a mixture when starting a cold engine during warm temperatures due VACUUM BREAK DIAPHRAGM THROTTLE VALVE MANIFOLD VACUUM THERMOSTATIC COIL amp ROD Fig 7 Choke System to choke coil cooling causing the choke valve to be too far closed The auxiliary diaphragm unit is controlled by a vacuum switch which is operated by engine coolant temperature When the engine is started at temperatures above 80 F the vacuum switch opens and allows mani
297. e following vacuum motor check a Turn off engine Disconnect diaphragm assembly vacuum hose at sensor unit b Apply at least 9 in Hg of vacuum to diaphragm assembly through the hose This can be done by mouth Damper door should completely close snorkel passage when vacuum is applied If not check to see if linkage is hooked up correctly Also check for a vacuum leak ENGINE FUEL 6M 69 GASKET POSITION COLORED SURFACE gt EXTENSION Fig 13C Air Cleaner L6 Non Intergrated Head c With vacuum applied bend or clamp hose to trap vacuum in diaphragm assembly Damper door should remain in position closed snorkel passage If it does not there is a vacuum leak in diaphragm assembly Replace diaphragm assembly 5 If vacuum motor check is found satisfactory replace sensor unit Vacuum Motor Replacement Removal 1 Remove air cleaner from engine 2 Drill out spot welds fastening vacuum motor retaining strap to snorkel tube 3 Remove vacuum motor by lifting and unhooking linkrod from damper door Replacement 1 Drill 7 64 hole in snorkel tube at center of vacuum motor retaining strap fig 19C 2 Connect vacuum motor linkage to damper door Fasten retaining strap to air cleaner with sheet metal screw 3 Replace air cleaner on engine and check operation of vacuum motor and control damper assembly Temperature Sensor Replacement Removal 1 Remove air cleaner from engine and disco
298. e for binding conditions If air valve is damaged air horn assembly must be replaced Check all throttle levers and valves for binds or other damage ASSEMBLY Throttle Body 1 If removed install idle mixture needles and springs until seated Back out the mixture needles 4 turns as a preliminary idle adjustment Final adjustment must be made on the engine using the procedures described under slow idle adjustment Install lower end of pump rod in throttle lever by aligning tang on rod with slot in lever End of rod should point outwards towards throttle lever Float Bowl Assembly l Install new throttle body to bowl gasket over two locating dowels on bowl Install throttle body making certain throttle body is properly located over dowels on float bowl then install throttle body to bowl screws and tighten evenly and securely Fig 18MQ Place carburetor on proper holding fixture J 8328 Install fuel inlet filter spring filter new gasket and inlet nut and tighten nut to 18 pounds feet Fig 17MQ NOTE Ribs on closed end of filter element prevent filter from being installed incorrectly unless forced CAUTION Tightening beyond specified torque can damage nylon gasket Choke 1 Install new cup seal into plastic insert on side of float bowl for intermediate choke shaft Lip on cup seal faces outward Install secondary throttle valve lock out lever on boss on float bowl with recess i
299. e for pipe repair within 4 inches of any part of the exhaust system 2 In repairable areas cut fuel hose 4 inches longer than Fig 1 Fuel Tank 50 Gal Meter and Filler Neck P30 Model the portion of pipe removed Use only hose stated for TRUCK SUPP SERVICE 8 2 FUEL TANK AND EXHAUST SYSTEM fuel usage by the manufacturer If more than a 6 inch length of pipe is removed use a combination of steel pipe and hose so that hose lengths will not be longer than 10 inches 3 The fuel hose should extend 2 inches on each pipe and be clamped at each end Pipes must be properly secured to the frame to prevent chafing EXHAUST SYSTEM GENERAL DESCRIPTION For alignment purposes the muffler outlet flange is notched and mates to a welded tab located on the outside diameter of the tailpipe The exhaust pipes and muffler use locater tabs for alignment The C10 with light duty emissions except 454 V8 and G10 vehicles have an exhaust system with a catalytic converter between the front exhaust pipe and the rear exhaust pipe The catalytic converter is an emission control device added to the exhaust system to reduce hydrocarbon and carbon monoxide pollutants from the exhaust gas stream The converter contains beads which are coated with a catalytic material containing platinum and palladium The catalytic converter requires the use of unleaded fuel only Periodic maintenance of the exhaust system
300. e idle mixture may be adjusted Before suspecting idle mixture as cause of poor idle quality check ignition system distributor timing air cleaner PCV system evaporation emission control and compression pressures lso check all vacuum hoses and connections for leaks and check torques of carburetor attachment bolts Adjustment is made using a tachometer Idle Mixture Adjustment 1 With engine at normal operating temperature air cleaner on choke open and air conditioning OFF connect a tachometer to engine 2 Set parking brake and block drive wheels 3 Disconnect vacuum advance hose at distributor and plug hose 4 Start engine check timing and adjust as required Reconnect vacuum advances hose 5 With engine at normal operating temperature not hot air conditioning off and air cleaner installed position transmission selector in Drive automatic transmission or Neutral manual transmission 6 Break off tab on mixture cap using needle nose pliers 7 Adjust idle rpm to the higher of the two idle speeds specified Example 650 600 8 Equally enrich turn out mixture screws until maximum idle speed is achieved Reset speed if necessary to the higher specified idle speed 9 Equally lean turn in mixture screws until the lower specified idle speed is achieved Example 650 600 PUMP ROD ADJUSTMENT Fig 27 1 Back out idle speed adjusting screw 2 Hold throttle valve completely closed 3 Gauge fr
301. e link into slot in lower end of shaft Ends of drive link point inboard toward carburetor bore Tang on upper end of link retains link to pump shaft Fig 4 Install lower end of pump link into actuator lever which fits on throttle shaft Install curved power piston actuator link into throttle actuator lever End protrudes outward away from throttle bore and has tang which retains link to lever Before fastening power piston and pump actuator lever to end of throttle shaft hold power piston assembly down and slide upper end of curved power piston actuator link into lower end of power piston actuator rod Install actuating lever on end of throttle shaft by aligning flats on lever with flats on shaft Install lever retaining screw and tighten securely Install float needle valve into needle seat Install float hinge pin into float arm Then install float and hinge pin into float bowl Float Level Adjustment Fig 7 l 2 Hold float retaining pin firmly in place and push down on float arm at outer end against top of float needle Use adjustable T scale and measure distance from top of float at index point on toe to float bowl gasket surface gasket removed GAUGE FROM TOP OF N CASTING TOTOPOF INDEX POINT TOE OF FLOAT HOLD FLOAT RETAINING PIN FIRMLY IN PLACE PUSH DOWN ON END OF FLOAT ARM AGAINST TOP OF FLOAT NEEDLE BEND HERE TO ADJUST FLOAT UP OR DOWN Fig 7 Float Level Adju
302. e of ring facing coil using Snap Ring Pliers J 6435 26 4 Install pulley and bearing assembly as described in Compressor Pulley and Bearing Asm Replacement procedure 5 Install clutch plate and hub assembly as described in Compressor Clutch Plate and Hub Asm Replacement Procedure JJ Clutch Coil and Housing Assembly Snap Ring Pliers WR J 6435 26 w T Se WE s cna K Retainer Ring gt Fig 16 Removing Coil Housing Retainer Ring TRUCK SUPP OVERHAUL 1 8 AIR CONDITIONING COMPRESSOR ELECTRICAL TERMINALS Fig 17 Installing Coil Housing MAJOR A 6 COMPRESSOR REPAIR PROCEDURES Service repair procedures to the Compressor Shaft Seal Pressure Relief Valve and Superheat Switch or disassembly of the Internal Compressor Mechanism are considered MAJOR SINCE THE REFRIGERATION SYSTEM MUST BE COMPLETELY PURGED OF REFRIGERANT before proceeding and or because major internal operating and sealing components of the compressor are being disassembled and serviced A clean workbench preferably covered with a sheet of clean paper orderliness in the work area and a place for all parts being removed and replaced is of great importance as is the use of the proper clean service tools Any attempt to use make shift or inadequate equipment may result in damage and or improper compressor operation These procedures are based on the use of the proper service tools and the conditio
303. e primary bores and then goes on into the engine manifold and on to the engine cylinders as a combustible mixture TRUCK SUPP SERVICE 6 58 ENGINE FUEL As the throttle valves are opened further and engine speeds increase increased air flow through the secondary side of the carburetor opens the air valve to a greater degree which in turn lifts the secondary metering rods further out of the orifice plates The metering rods are tapered so that fuel flow through the secondary metering orifice plates is directly proportional to air flow through the secondary carburetor bores In this manner correct air fuel mixtures to the engine through the secondary bores can be maintained by the depth of the metering rods in the orifice plates There are two other features incorporated in the secondary metering system which are as follows 1 The main well bleed tubes extend below the fuel level in the main well These bleed air into the fuel in the well to blend the fuel with air quickly for good atomization as it leaves the secondary discharge nozzles 2 A baffle plate is used in the secondary bore Its purpose is to provide good fuel distribution by preventing too much fuel from going to the front of the engine Air Valve Dashpot Operation Fig 60 The secondary air valve is connected to a vacuum break diaphragm assembly by a rod to control the opening rate of the air valve and prevent any secondary discharge nozzle lag Whenever mani
304. e road disconnect the front drive shaft TRUCK SUPP SERVICE e If rear wheels are on the road disconnect the rear drive shaft STEEL TUBING REPLACEMENT In the event that replacement of steel tubing is required on brake line fuel line evaporative emission and transmission cooling lines only the recommended steel replacement tubing should be used Only special steel tubing should be used to replace brake line That is a double wrapped and brazed steel tubing meeting G M Specification 123 M Further any other steel tubing should be replaced only with the released steel tubing or its equivalent Under no condition should copper or aluminum tubing be used to replace steel tubing Those materials do not have satisfactory fatigue durability to withstand normal vehicle vibrations steel tubing should be flared using the upset double lap flare method which 1s detailed in Section 5 of this Manual VEHICLE LOADING Vehicle loading must be controlled so weights do not exceed the numbers shown on the Vehicle Identification Number and Rating Plate for the vehicle A typical example of a truck in a loaded condition is shown in Figure 4 Note that the axle or GVW capabilities are not exceeded GENERAL INFORMATION AND LUBRICATION 0 5 LOADED MAXIMUM GVWR 6200 LBS FRONT GAWR 3250 LBS REAR GAWR 3582 LBS AW SH ee EXAMPLE ONLY Front Curb 2261 lbs Rear Curb 1549
305. e the piston ring area with 525 viscosity refrigerant oil and rotate the Piston and Ring Assembly into the Ring Sizer J 24608 6 at a slight angle Fig 49 Rotate the piston while pushing inward until the piston is inserted against the center stop of the Ring Sizer J 23608 6 J 24608 6 RING SIZING TOOL J 24608 1 PISTON RING GAGE Fig 45 Teflon A 6 Piston Ring Installing Sizing and Gaging Tools TRUCK SUPP OVERHAUL TEFLON PISTON RING J 24608 2 RING INSTALLER GUIDE Fig 46 Teflon Piston Ring Positioned on Ring Installer Guide CAUTION DO NOT push the Piston and Ring Assembly into the Ring Sizer J 24608 6 without proper positioning and rotating as described above as the ends of the needle bearings of the Ring Sizer may damage the end of the piston 7 Rotate the Piston and Ring Assembly in the Ring Sizer J 24608 6 several COMPLETE turns until the Assembly rotates relatively free in the Ring Sizer Fig 49 8 Remove the Piston and Ring Assembly wipe the end of the piston and ring area with a clean cloth and then push the Piston and Ring Assembly into the Ring Gage J 24608 1 Fig 50 The piston should go through the Ring Gage with a 6 16 force or less without lubrication If not repeat Steps 6 and 7 9 Repeat the procedure for the opposite end of the piston CAUTION DO NOT lay the piston down on a dirty sur ace where dirt or metal chips might become imbedded in the Teflon ring surface 10 Lubr
306. e the vacuum break diaphragm assembly from air horn by removing two attaching screws Remove diaphragm and link assembly from lever on end of choke shaft 5 Remove vacuum break lever from end of choke shaft by removing retaining screw in end of shaft Then remove the intermediate choke rod from the vacuum break lever and from the lever on the thermostatic coil housing 6 Remove fast idle cam attaching screw from side of float bowl Remove fast idle cam from end of choke rod by rotating rod out of hole in fast idle cam The upper end 10 SPRING CLIP Fig 2C Removing Pump Rod Spring Clip of the choke rod cannot be removed from the choke lever until after the air horn has been removed from the float bowl Remove eight air horn attaching screws lockwashers then lift air horn from float bowl Fig 3C Place air horn on flat surface Remove float hinge pin and lift float from air horn Float needle and pull clip if used may now be removed from float arm Fig 4C Remove float needle seat and gasket with a wide blade screwdriver Remove power piston by depressing stem and allowing it to snap free Use care not to bend the power piston stem Fig 3C Removing Air Horn TRUCK SUPP OVERHAUL ACCELERATING INNER PUMP PUMP ASSEMBLY LEVER HINGE PIN AND SEAT Fig 4C Air Horn 11 Remove the pump plunger assembly and inner pump lever from pump shaft by loosening set screw on inner lever
307. e to internal pump components Take care to avoid nicks or scratches on pump pulley shaft POWER STEERING GEAR INTEGRAL Adjuster Plug Disassembly 1 If the oil seal ONLY is to be replaced and not the needle bearing install the adjuster plug Fig 3 loosely in the gear housing Remove the retaining ring with Internal Pliers J 4245 With a screwdriver pry the dust seal and oil seal from the bore of the adjuster plug being careful not to score the seal bore Discard the oil seal TRUCK SUPP OVERHAUL 9 2 STEERING 490 Ring Retaining Seal Stub Shaft Dust Seal Stub Shaft Bearing Upper Thrust Bearing Needle 9 Plug Adjuster 10 Seal O Ring Adjuster 11 Spacer Thrust Bearing Retainer Bearing P Race Upper Bearing Large t Race Upper Thrust Bearing Small sxm EEUU A ee Fig 3 Adjuster Plug NEEDLE BEARING RETAINER SCREW DRIVER Fig 4 Removing Retainer If the thrust bearing ONLY is to be removed pry the thrust bearing retainer at the two raised areas with a small screwdriver Fig 4 Remove the spacer thrust bearing race thrust bearing and the flanged thrust bearing race If the needle bearing is to be replaced remove the retaining ring using Internal Pliers J 4245 Remove thrust bearing as outlined in Step 2 above Drive needle bearing dust seal and oil seal from adjuster plug using Bearing Remover J 8524
308. eak plunger head Then install rear vacuum break control and bracket assembly to float bowl using two attaching screws Fig 14MQ Tighten securely NOTE Do not attach vacuum break hose until after the vacuum break adjustment is complete Refer to Service Section for adjustment procedure All Models 3 If removed install air baffle in secondary side of float bowl with notches toward the top Top edge of baffle must be flush with bowl casting CHOKE ROD LEVER Fig 20MQ Installing Choke Rod Lever TRUCK SUPP OVERHAUL 6 18 CARBURETOR 10 If removed install baffle in pump well fill slot Install pump discharge check ball and retainer in passage next to pump well Tighten retainer securely Install primary main metering jets Fig 13MQ Install aneroid cavity insert into float bowl Install new needle seat assembly with gasket To make adjustment easier bend float arm upward at notch in arm before assembly Install needle by sliding float lever under needle pull clip correct installation of the needle pull clip is to hook the clip over the edge of the float on the float arm facing the float pontoon Fig 21 With float lever in pull clip hold float assembly at toe and install retaining pin from aneroid cavity side ends of retaining pin face the accelerating pump well CAUTION Do not install float needle pull clip into holes in float arm Adjust float lev
309. eal TRUCK SUPP OVERHAUL SECTION 4 REAR AXLE DIFFERENTIAL OVERHAUL GENERAL INFORMATION Except for one modification in the Dana 10 1 2 Axle all overhaul procedures found in section 4 of the 1974 Overhaul Manual are applicable to 1976 differentials Two items should be noted e Note the 8 1 2 axles on G10 models in figure 1 Procedures for these units are listed under Passenger Car 8 1 2 Ring Gear in the 1974 Overhaul manual e The 62003 Dana differential is overhauled in an identical manner to the 7500 Dana DANA 10 1 2 RING GEAR DIFFERENTIAL Modification The differential shown on page 4 55 of the 1974 Overhaul Manual has been modified or some vehicles For these modified units 1 The differential case item 14 on page 4 55 15 now a one piece design 2 The pinion spider item 21 is now a pinion shaft using two pinion gears rather than four PINION DEPTH SETTING USE OF DIAL INDICATOR It is important to use a dial indicator correctly when determining pinion depth requirements Be sure to record the number indicated by the indicator needle do not record the amount of travel of the needle After zeroing the dial indicator on the highest point of deflection on the gauge plate the indicator probe is swung off the gauge plate allowing the needle to move The number which the needle points toward is the correct shim thickness required for a nominal pinion See figure 2 TRUCK SUPP OVERHA
310. easure 3 25 quarts Imperial measure Recommended Viscosity Select the proper oil viscosity from the following chart The proper oil viscosity helps assure good cold and hot starting Checking Oil Level The engine oil should be maintained at proper level The best time to check it is before operating the engine or as the last step in a fuel stop This will allow the oil accumulation in the engine to drain back in the crankcase To check the level remove the oil gauge rod dipstick wipe it clean and reinsert it firmly for an accurate reading The oil gauge rod is marked i i es eieieienemmm r n m E REEEEEEEEEEEEEEEEEIIEa IMCCMC uuu GENERAL INFORMATION AND LUBRICATION 0 7 To help assure good cold and hot starting as well as maximum engine life fuel economy and oil economy select the proper viscosity from the temperature range anticipated from the following chart RECOMMENDED SAE VISCOSITY GRADES 20W 20 10W 30 10W 40 20W 40Ww 20W 50 TOW 5W 30 10W 30 10W 40 ere oca AIOA rn r Te 30 0 TEMPERATURE RANGE ANTICIPATED BEFORE NEXT OIL CHANGE NOTE SAE 5W 30 oils are recommended for all seasons in vehicles normally operated in Canada SAE 5W 20 oils are not recommended for sustained high speed driving SAE 30 oils may be used at temperatures above 40 F 4 C FULL and ADD OIL If the oil is at or below the ADD mark on the dipstick oi
311. eath the power piston hanger being careful not to distort springs holding the main metering rods Fig 8MQ 2 Remove pump plunger from pump well 3 Remove pump return spring from pump well 4 Remove power piston and metering rods by depressing piston stem and allowing it to snap free Fig 9 The power piston can be easily removed by pressing the piston down and releasing it with a snap This will cause the power piston spring to snap the piston up against the retainer This procedure may have to be repeated several times CAUTION Do not remove power piston by using pliers on metering rod hanger Remove the power piston spring from the well CAUTION The A P T metering rod adjustment screw is pre set at the factory and no attempt should Fig 6MQ Removing Air Horn be made to change this adjustment the field If float bowl replacement is required during service the new bowl assembly will be supplied with an A P T 1 Remove staking on two choke valve attaching screws metermz rod screw which willbe preset as required then remove choke valve and shaft from air horn 5 Remove metering rods from power piston by disconnecting tension spring from top of each rod then 2 Air valves and air valve shaft should not be removed rotate rod to remove from hanger Fig 10 3 valve CAUTION Use care when disassembling rods to necessary to repiaCe Valve e prevent d
312. ected directly to the throttle lever by a pump rod When the pump plunger moves upward in the pump well as happens during throttle closing fuel from the float bowl enters the pump well through a slot in the top of the pump well It flows past the synthetic pump cup seal into the bottom of the pump well The pump cup is a floating type which moves up and down on the pump plunger head When the pump plunger is moved upward the flat on top of the cup inseats from the flat on the plunger head and allows free movement of fuel through the inside of the cup into the bottom of the pump well This also vents any vapors which may be in the bottom of the pump well so that a solid charge of fuel can be maintained in the fuel well beneath the plunger head When the primary throttle valves are opened connecting linkage forces the pump plunger downward The pump cup seats instantly and fuel is forced through the pump discharge passage where it unseats the pump discharge check ball and passes on through the passage to the pump jets located in the air horn where it sprays into the venturi area of each primary bore It should be noted the pump plunger is spring loaded The upper duration spring is balanced with the bottom pump return spring so that a smooth sustained charge of fuel is delivered during acceleration PUMP PUMP SUCTION BREAKER PLUNGER DURATION SPRING DISCHARGE BALL RETAINER DISCHARGE PASSAGE Y CUP SEAL E
313. ecting idle mixture as case of poor idle quality check ignition system distributor timing air cleaner PCV system evaporation emission control and compression pressures Also check all vacuum hoses and connections for leaks and check torques of carburetor attachment bolts Adjustment is made using a tachometer Idle Mixture Adjustment 1 With engine at normal operating temperature air cleaner on choke open and air conditioning OFF connect a tachometer to engine 2 Set parking brake and block drive wheels 3 Disconnect fuel tank hose from vapor canister on California vehicle 4 Disconnect vacuum advance hose at distributor and plug hose 5 Start engine check timing and adjust as required Reconnect vacuum advance hose 6 With engine at normal operating temperature not hot air conditioning off and air cleaner installed position transmission in Neutral 7 Break off tab on mixture cap using needle nose pliers 8 Adjust idle rpm to the higher of the two idle speeds specified Example 650 600 9 Equally enrich turn out mixture screws until maximum idle speed is achieved Reset speed if necessary to the higher specified idle speed 10 Equally lean turn in mixture screws until the lower specified idle speed is achieved Example 650 600 11 Stop engine and remove tachometer 12 Connect fuel tank vent hose FAST IDLE ADJUSTMENT FIG 9Q 1 Check for correct idle speed 2 Set parking brake an
314. ee cle 9 9 9 es S el amp x lt lt S 1 5 2 z x x 9 919 m m st tis x eo lt lt x 9 cc e o n gt EH 32 Ee EE 5 5 lt lt lt ex eo se eo DO D i na Rum oni n eo t gt 50 gt 19 2 gt na Ur Exam e T ce ini E co co to I e i gt En rz B 3 4 o e 1 4 1 2 1 2 Fig 1 C K P Truck Reference Dimensions e e e a a a e e e e els x wo ce gt O gt lt ed e rz eo lt 21212 gt 5 Ww e S o e e e ex TRUCK SUPP SERVICE p UUUUUEM6MA 2 2 FRAME DIMENSIONS TO HOLES OR SLOTS ARE MEASURED TO THE CENTER OF HOLE OR SLOT GAUGE HOLES ARE 5 8 DIAMETER INDICATES THAT THE DIMENSION IS TO THE UNDERSIDE OF THE FRAME TOP SURFACE OR INSIDE OF THE FRAME OUTER SURFACE NOTE FRAME ILLUSTRATED IS TYPICAL FRAME DESIGN V
315. eene ette rte 9 4 Power Steering Gear sese 9 1 Power Steering Pump seen 9 4 Service Operations 9 3 Power Steering Hoses eee 9 4 Steering Wheel sese 9 3 Bleeding Power Steering Systems 9 4 Directional Signal Switch esse 953 Special Tools 06 i 9 12 GENERAL DESCRIPTION All 1976 truck models have basically the same steering systems as the 1974 models All service procedures outlined in the 1974 Light Duty Truck Service Manual apply as well to the 1976 truck steering systems except the following procedures MAINTENANCE AND ADJUSTMENTS POWER STEERING PUMP BELT ADJUSTMENT The effect of improperly adjusted worm thrust bearings or Power steering belt adjustment for 1976 truck models is identical to the procedure outlined in the 1974 Light Duty Truck Service Manual Section 9 Page 9 27 with the handling stability complaint exception of a 1 2 spuare hole in the support bracket on some engines to aid in belt adjustment as shown in Fig 8 Use a 1 2 drive ratchet or breaker bar handle inserted in the hole to assist on obtaining proper belt adjustment POWER STEERING GEAR Adjustment of the power steering gear in the vehicle is discouraged because of the difficulty involved in adjusting the worm thrust bearing preload and the confusing effects For removal of the power steering gear assembly follow the of the hydraulic
316. el Float Level Fig 22MQ 11 a Hold float retainer firmly in place b Push float down lightly against needle c With adjustable T scale gauge from top of float bowl casting air horn gasket removed to top of float gauging point 1 16 back from end of float at toe d Bend float arm as necessary for proper adjustment by pushing on pontoon Refer to adjustment chart for specification e Visually check float alignment after adjustment Install plastic filler block over float needle pressing downward until properly seated FLOAT NEEDLE PULL CLIP LOCATION HOOK CLIP OVER EDGE OF FLAT ON FLOAT ARM FACING FLOAT PONTOON lor N 29 HOOK PULL CLIP IN THESE HOLES S Fig 21MQ Pull Clip Location 12 13 Install air horn gasket by carefully sliding tab of gasket 15 Install power piston spring in power piston well If main metering rods were removed from hanger reinstall making sure tension spring is connected to top of each rod Fig 9MQ Install power piston assembly in well aligning pin on piston with slot in well with metering rods properly positioned in metering jets Press down firmly on plastic power piston retainer to make sure the retainer is seated in recess in bowl and the top is flush with the top of the bowl casting If necessary using a drift punch and small hammer tap retainer lightly in place Install pump return spring in pump well
317. eleased slowly from the fully depressed position it will engage the system at the existing speed and cruise at that speed above 30 mph NOTE See Fig Engage Switch Operation Speed Changes Override The accelerator pedal may be depressed at any time to override the cruise system Release of the accelerator pedal will return the vehicle to the previous cruise speed To Cruise At A Higher Speed Depress the accelerator pedal to reach the new desired speed Then fully depress and slowly release the cruise control engagement switch button The system re engages at the higher speed when the button is slowly released To Cruise At A Lower Speed Disengage the system by depressing the engagement switch button fully and holding it there until the vehicle has decelerated to the new desired speed then release the button slowly The system re engages at the lower speed when the button is slowly released CRUISE MASTER UNITS Figures 3C and 4C show the units in the installed position on the vehicles 1 The Engagement Switch which is located at the end of the directional signal lever or bottom on instrument panel is used to control the system and for upward and downward speed adjustments 2 The Regulator fig 2C is mounted in the speedometer cable line It is a combination speed sensing device and control unit When engaged it senses vehicle speed and positions the Servo Unit to maintain the selected speed 3
318. em of refrigerant 2 Disconnect the condenser to evaporator line at the evaporator inlet 3 Using needle nose pliers and gripping the plastic tip of the expansion tube remove the expansion tube and O ring from the core inlet line Installation l Insert the new expansion tube into insertion tool J 26549 as illustrated in figure 12 2 Coat a new expansion tube O ring with clean 525 viscosity refrigeration oil 3 While slightly compressing the fingers of the tool around the body of the expansion tube to facilitate entry into the inlet line insert the expansion tube into the core inlet line and push until the tube reaches a firm stop This will indicate proper seating of the O ring in the inlet line TRUCK SUPP SERVICE SECTION 1B TRUCK BODY NOTE Except for the items listed below all information found in section 1B of the 1974 Light Duty Truck Service Manual is applicable to 1976 Light Duty Trucks INDEX Fig 1 Cowl Vent Valves COWL VENT VALVES Two styles are shown in figure 1 Removing the attaching screws allows removal of the valve from the side panels Refer to page 1B 6 of the 1974 manual REAR SIDE DOOR MODELS 06 AND 03 Glass Run Channel Adjustment Figure 2 illustrates the front run channel At the lower end a slotted bracket provides for in and out adjustment The screw and locknut at that bracket allow fore and aft adjustment ADJUSTMENT SLOT IN BRACKET for in and out
319. embly out see Fig 20 6 Remove the seal seat O ring from the compressor neck using O Ring Remover J 9533 See Fig 19 7 Recheck the shaft and inside of the compressor neck for dirt or foreign material and be sure these areas are perfectly clean before installing new parts Inspection SEALS SHOULD NOT BE REUSED ALWAYS USE A NEW SEAL KIT ON REBUILD Be extremely careful that the face of the seal to be installed is not scratched or damaged in any way Make sure that the seal seat and seal are free of lint and dirt that could damage the seal surface or prevent sealing Replace 1 Coat new seal seat O ring with clean 525 viscosity refrigerant oil and install in compressor neck making certain it is installed in bottom groove Fig 20 and Fig 21 Top groove is for retainer ring Use O Ring Installer J 21508 2 Coat the O ring and seal face of the new seal assembly with clean 525 viscosity refrigerant oil Carefully mount the seal assembly to Seal Installer J 9392 by engaging the tabs of the seal with the tangs of the tool Fig 20 3 Place Seal Protector J 22974 Fig 20 over end of shaft and carefully slide the new seal assembly onto the shaft Gently twist the tool CLOCK WISE while pushing the seal assembly down the shaft until the seal assembly engages the flats on the shaft and is seated in place Disengage the tool by pressing downward and twisting tool counterclockwise 4 Coat the seal face of the new seal seat
320. ems requires new adjustment procedures Also refer to Section 6T Emission Control System for additional information The primary side of the carburetor has six systems of operation They are float idle main metering power pump and choke The secondary side has one metering system which supplements the primary main metering system and receives fuel from a common float chamber TRUCK SUPP SERVICE 6M 32 ENGINE FUEL Fig 36 M4MC Quadrajet Carburetor Fig 36A M4ME Quadrajet Carburetor THEORY OF OPERATION FLOAT SYSTEM Fig 37 The float system operates in the following manner Fuel from the engine fuel pump enters the carburetor fuel inlet passage It passes through the pleated paper filter element fuel inlet valve and on into the float bowl chamber As the incoming fuel fills the float bowl to the prescribed level the float pontoon rises and forces the fuel inlet valve closed shutting off fuel flow As fuel is used from the float bowl the float drops allowing the float valve to open when more fuel again fills the bowl This cycle continues maintaining a constant fuel level in the float bowl A new float assembly is used for improved fuel handling in the float bowl The float pontoon is solid and is made of a light weight closed cell plastic material This feature gives added buoyancy to allow the use of a single float to maintain constant fuel levels A float pull clip fastened to the float valve hooks over t
321. en against spring tension This allows the required air for increased engine speed to flow past the air valve When the air valve begins to open the upper edge of the air valve passes the accelerating well discharge port As the valve passes the port it exposes the port to manifold vacuum The port will immediately start to feed fuel from the accelerating wells The accelerating ports prevent a momentary leanness as the valve opens and the secondary nozzles have not begun to feed fuel Discharge from the ports stops after the edge of the valve has passed the port The secondary main discharge nozzles one for each secondary bore are located just below the air valve and above the secondary throttle valves Being in an area of low pressure they begin to feed fuel as follows When the air valve begins to open it rotates a plastic cam attached to the center of the main air valve shaft The cam pushes upward ona lever attached to the secondary metering rods raising the metering rods out of the secondary orifice plates Fuel flows from the float chamber through the secondary orifice plates into secondary main wells where it is mixed with air from the main well tubes at the bottom of the main wells The air blended fuel mixture travels from the main wells to the secondary discharge nozzles and into the secondary bores Here fuel mixture is mixed with air traveling through the secondary bores to supplement the air fuel mixture delivered from th
322. ening the nut 135 Ft Lbs when tightening the bolt TRUCK SUPP SPECS SPECIFICATIONS 8 Master Cylinder to Dash or Booster Booster to Dash or Frame Combination Valve Mounting Bolts Bracket to Frame Caliper Mounting Bolt Support Plate to Knuckle Brake Pedal Bracket to Dash Bracket to I P Pivot Bolt Nut Sleeve to Bracket Stoplamp Switch Bracket Push Rod to Pedal Push Hod Adiusting Nut 10 Dash to I P Kick Panel or Floorpan Cable Clips Screws Bolts Parking Brake Propshaft Parking Brake Adjusting Nut Bracket to Trans Cable Clip to Frame Cable Clip to Dash Cable Clip to Trans Flange Plate Drum Brkt BRAKES SECTION 5 TORQUE SPECIFICATIONS C 150 in Ibs 115 in 16 17 ft Ibs x Sc 256 K 25 ft 25 ft Ibs Ibs Wheel Cylinder to Flange Plate Bolt Rear Brake Anchor Pin Front Brake Hose io Caliper to Frame Nut Bracket Bolt to Axle Bracket Bracket to Axle Attaching Nuts Hear Brake Hose Brake Line Retaining Clips Screws Bolts Brake Bleeder Valves Hydro Boost Pedal Rod P30 32 Models Pedal Rod Boot P30 32 Models Pivot Lever Rod Retainer Pivot Lever Bolt Booster Brackets Booster Brace at Dash or Rad Supt Power Steering Pump to Booster Line Booster to Gear Line Return Line at Booster amp Gear Return Line Clamp Screw Line Clamp to Bracket
323. ent at the top of the main well and side bleeds The fuel in the main well is mixed with air from the main well air bleeds and then passes through the main discharge nozzle into the boost venturi At the boost venturi the fuel mixture then combines with the air entering the engine through the carburetor bores and passes through the intake manifold and on into the engine cylinder as a combustible mixture The main metering system is calibrated by tapered and stepped metering rods operating in metering jets and also through the main well air bleeds POWER SYSTEM FIG 5Q The power system provides mixture enrichment for power requirements under acceleration high loads or high speed operation The richer mixture is supplied through the main metering system in the primary side of the carburetor The power system located in the primary side consists of a vacuum piston and spring located in a cylinder connected by a passage to intake manifold vacuum The spring located beneath the vacuum operated power piston tends to push the piston upward against manifold vacuum On part throttle and cruising ranges manifold vacuum is sufficient to hold the power piston down against spring tension so that the larger diameter of the metering rod tip is held in the main metering jet orifice Mixture enrichment is not necessary at this point However as engine load is increased to a point where mixture enrichment is required the spring tension overcomes the va
324. enting through a vent hole in the air horn which leads from the float bowl into the bore beneath the air cleaner The carburetor model identification is stamped on a vertical portion of float bowl adjacent to fuel inlet nut Figure 1 If replacing float bowl follow manufacturer s instructions contained in the service package so that the identification number can be transferred to the new float bowl An electrically operated idle stop solenoid is used on all models Dual throttle return springs are used on all carburetors All carburetor models have an idle mixture screw and limiter The plastic limit cap permits idle mixture screw to be adjusted leaner without breaking the cap At carburetor overhaul the mixture may be adjusted CAUTION Do not bend the mixture screw when cutting the tang To get the best idle and keep emissions within standards set by law always follow adjustment procedures and specifications see Idle Mixture Adjustment An Exhaust Gas Recirculation system E G R is used on all applications to control oxides of nitrogen The vacuum supply port necessary to operate the recirculation valve is located in the throttle body and connects through a channel to a tube which is located at the top of the air horn casting Six basic systems of operation are used float idle main metering power enrichment pump and choke THEORY OF OPERATION FLOAT SYSTEM Fig 2 The float system controls th
325. equired Replace muffler assembly Replace exhaust pipe Tighten attaching bolts nuts to 17 foot pounds Replace manifold Tighten manifold to cylinder head stud nuts or bolts to specifications Replace muffler Replace exhaust pipe TRUCK SUPP SERVICE FUEL TANK AND EXHAUST SYSTEM 8 9 SPECIAL TOOLS 1 J 25077 1 Vibrator Include Catalyst Container and Fill Tube Extension 2 J 25077 2 Aspirator Fig 1ST Special Tools TRUCK SUPP SERVICE SECTION 9 STEERING The following caution applies to one or more steps in the assembly procedure of components in this portion of the manual as indicated at appropriate locations by the terminology See Caution on Page 1 of this Section CAUTION 7HIS FASTENER IS AN IMPORTANT ATTACHING PART IN THAT IT COULD AFFECT THE PERFORMANCE OF VITAL COMPONENTS AND SYSTEMS AND OR COULD RESULT IN MAJOR REPAIR EXPENSE IT MUST BE REPLACED WITH ONE OF THE SAME PART NUMBER OR WITH AN EQUIVALENT PART IF REPLACEMENT BECOMES NECESSARY DO NOT USE A REPLACEMENT PART OF LESSER QUALITY OR SUBSTITUTE DESIGN TORQUE VALUES MUST BE USED AS SPECIFIED DURING REASSEMBLY TO ASSURE PROPER RETENTION OF THIS PART INDEX General Description eene 9 1 Steering Linkage eene 9 3 Maintenance and Adjustments esee 9 1 Idler sinerent ete itis 9 3 Power Steering Pump Belt Adjustment 9 1 Tie iine nera ero
326. er end of choke rod part number or identification faces outward on fast idle cam assembly Then install the fast idle cam to float bowl retaining with the fast idle cam attaching screw Tighten securely Move linkage up and down to make sure that the cam will fall freely 5 Install pump rod into upper pump lever by rotating offset end into hole in lever and install lower end of pump rod to throttle lever and retain with a spring clip Fig 2C 6 Install vacuum break diaphragm assembly onto air horn with two attaching screws Tighten securely 7 Install lower end of intermediate choke rod into intermediate choke lever on choke housing and connect upper end of rod to vacuum break lever Install vacuum break diaphragm rod into stem of vacuum break diaphragm and vacuum break lever 8 Install the vacuum break lever onto end of choke shaft making sure that the lever fits over flats on shaft Install attaching screw and tighten securely 9 Connect vacuum break hose to diaphragm unit and vacuum tube on throttle body After complete carburetor assembly check and re set if necessary all choke adjustments and pump rod adjustments TRUCK SUPP OVERHAUL CARBURETOR 6 11 M4MC M4ME QUADRAJET CARBURETOR INDEX h uci esu tes erp e 6M 11 Disassembly eX qaa a anu ua 6M 11 Cleaningz nd Inspection 2 6 16 6 17 Special
327. er steering pump belt slips 1 Tighten belt 2 Low fluid level in power steering 2 Fill reservoir and check for pump reservoir external leaks 3 Faulty spool operation caused by 3 Inspect clean and replace 11 contamination in system booster seals 4 Excessive contamination in power 4 Flush power steering fluid from steering fluid system and replace with new power steering fluid 5 Air in power steering fluid 5 Allow vehicle to stand for approximately one hour then bleed power steering hydraulic system as described earlier in this section TRUCK SUPP SERVICE 5 20 BRAKES DIAGNOSIS HYDRO BOOST SYSTEM POWER STEERING PUMP NOISE ON BRAKE APPLY Probable Cause Remedy 1 Insufficient fluid in pump 1 Fluid level decreases approximately reservoir 1 2 on brake apply refill to proper level If fluid is foamy let vehicle stand for approximately one hour then bleed power steering hydraulic system as outlined earlier in this section BRAKE PEDAL PULLS DOWN SLIGHTLY ON ENGINE START Probable Cause Remedy 1 Restriction in gear or booster 1 Replace lines or reposition return lines lines to eliminate restriction ACCUMULATOR LEAKDOWN SYSTEM DOES NOT HOLD CHARGE Preliminary Check Start engine and turn the steering wheel until the wheels contact the wheel stops lightly Hold for a maximum of five seconds Then release the steer
328. erates during off idle part throttle and wide open throttle operation This provides a larger purge capacity for the vapor canister and prevents over rich mixtures from being added to the carburetor metering at any time MAIN METERING SYSTEM Fig 39 The main metering system supplies fuel to the engine from off idle to wide open throttle The primary bores two smaller bores supply air and fuel during this range Separate main wells feed each fuel nozzle to improve fuel flow in the venture system As the primary throttle valves are opened beyond the off idle range allowing more air to enter the engine intake manifold air velocity increases in the carburetor venturi to cause the main metering system to operate as follows Fuel from the float bowl flows between the main metering rods and jets into the main fuel wells It passes upward in the main well and is bled with air by an air bleed located at the top of the well The fuel is further bled air through calibrated air bleeds located near the top of the well in the carburetor bores The fuel mixture then passes from the o NR C LI 5 main well through the main discharge nozzles into the boost venturi At the boost venturi the fuel mixture then combines with the air entering the engine through the carburetor bores It then passes as a combustible mixture through the intake manifold and on into the engine cylinders The main meterin
329. eres RPM 5500 10500 5500 10500 9 50 80 3500 6000 Battery Size 50 80 2900 Watts 2438 3563 2900 Watts 65 90 7500 10500 LF4 LF5 LS9 T mpm Exc P30032 1108782 454 V8 LF8 3563 4000 Watts 9 65 90 7500 10500 230032 Includes Solenoid GENERATORS Application Model No 1102478 1102479 1102480 1102489 P Truck 292 L 6 Base 1102490 L 6 with K76 1102394 All C K G Truck Exc G30003 V 8 Base All Exc P31832 V 8 Base All V 8 with K79 Generator temperature approximately 80 F Ambient Temperature 80 F All L 6 with C42 All V 8 with C42 All V 8 with K76 P31832 Truck 454 V 8 Base G30003 Truck 350 V 8 Base All L 6 with K79 1102491 All 250 L 6 Base 4519 40 45 G Truck 292 L 6 Base 0 4522 4 0 4 5 4521 4 0 4 5 Delco Remy Field Current Amps Cold Output Rated Hot Spec No 80 F Amps 5000 Output Amps 12 Volts i 4520 40 45 55 51 55 EK 57 4519 40 45 33 38 42 TRUCK SUPP SPECS SPECIFICATIONS 18 1112863 1110667 1110666 1112887 1110664 1112880 1112905 1112888 APPLICATION L 6 250 LD4 C 10 03 4 Spd Trans C 10 03 amp C 10 Auto Trans L 6 250 LD4 C amp G 10 Manual Trans 1 6 250 104 C amp G 10 Auto Trans L 6 25
330. ert specified gauge between upper edge of choke valve and air horn wall 4 If adjustment is required bend tang on throttle lever 71 HOLD DOWN ON CHOKE VALVE ROD IN END OF SLOT 3 GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND AIR HORN WALL 4 BEND UNLOADER TANG ON THROTTLE LEVER TO ADJUST SEE INSET 2 HOLD THROTTLE VALVE COMPLETELY OPEN Fig 15 Choke Unloader Adjustment 1MV SERVICE OPERATIONS CARBURETOR REPLACEMENT Fig 16 Removal Flooding stumble on acceleration and other performance complaints are in many instances caused by presence of dirt water or other foreign matter in carburetor To aid in diagnosing cause carburetor should be carefully removed from engine without draining fuel from bowl Contents of fuel bowl may then be examined for contamination as carburetor is disassembled Check filter 1 Remove air cleaner and gasket Disconnect fuel and vacuum lines from carburetor Disconnect choke coil rod Disconnect accelerator linkage Disconnect idle stop solenoid electrical connector N If equipped with automatic transmission disconnect detent control cable 7 Remove carburetor attaching nuts and remove carburetor and solenoid assembly attachment 8 Remove insulator Installation It is good shop practice to fill carburetor bowl before installing carburetor This reduces strain on starting motor and battery and reduces the possibility of backfi
331. est idle while maintaining emission levels within standards prescribed by Federal Law At major carburetor overhaul the idle mixture may be adjusted Before suspecting idle mixture as cause of poor idle quality check ignition system distributor dwell and timing air cleaner PCV system evaporation emission control and compression pressures lso check all vacuum hoses and connections for leaks and check torques of carburetor attachment bolts Adjustment is made using a tachometer Idle Mixture Adjustment 1 With engine at normal operating temperature air cleaner on choke open and air conditioning OFF connect a tachometer to engine 2 Set parking brake and block drive wheels 3 Disconnect vacuum advance hose at distributor and plug hose 4 Start engine check timing and adjust as required Connect vacuum advance hose 5 With engine at normal operating temperature not hot air conditioning off and air cleaner installed position transmission selector in Drive automatic transmission and light duty emissions or Neutral automatic transmission an heavy duty emissions and all manual transmissions 6 Break off tabs on mixture caps using needle nose pliers 7 Adjust idle rpm to the higher of the two idle speeds specified Example 650 600 8 Equally enrich turn out mixture screws until maximum idle speed is achieved Reset speed if necessary to the higher specified idle speed 9 Equally lean turn in mixt
332. eter 6M 55 Vacuum Break Adjustment 6M 61 Float System 55e rendering e 6M 55 Choke Unloader Adjustment 6M 61 Idle System ettet 6 55 Choke Coil Rod Adjustment 6M 62 Main Metering System eese 6M 56 Secondary Throttle Valve Lock Out Adjustment 6M 62 Power Systems certiores rte eitis 6M 57 Secondary Closing Adjustment 6M 62 Accelerating Pump System sss 6M 58 Secondary Opening Adjustment 6M 63 Choke System uk aret rte eerie 6M 59 Air Valve Spring Wind Up Adjustment 6M 63 Maintenance and Adjustment 6M 60 Throttle Lever Actuator Adjustment 6M 63 Idle Speed Adjustment orla netten 6M 60 Service Operations 2504 6 64 Idle Mixture Adjustment 6M 60 Carburetor 6M 64 Fast Idle Adjustment eene 6M 60 Fuel Filter Replacement 2 0 6M 64 Choke Rod Fast Idle Cam Adjustment 6M 60 Air Horn Tightening Sequence 6M 64 Pump Rod Adjustment essen 6M 61 DIagnOSlS interrete eer Pee ees erre regiae aus 6M 65 GENERAL DESCRIPTION The non California and California 350 400 V8 an
333. etor To aid in diagnosis carburetor should be carefully removed from engine without draining fuel from bowl Contents of fuel bowl may then be examined for contamination as carburetor is disassembled Check filter 1 Remove air cleaner and gasket 2 Disconnect fuel and vacuum lines from carburetor 3 Disconnect fresh air hose and choke hose from choke system 4 Disconnect accelerator linkage 5 If equipped with automatic transmission disconnect detent cable 6 Remove carburetor attaching bolts and carburetor remove 7 Remove insulator Installation It is good shop practice to fill carburetor bowl before installing carburetor This reduces strain on starting motor and battery and reduces the possibility of backfiring while attempting to start engine A small supply of fuel will enable carburetor to be filled and the operation of float and intake needle and seat to be checked Operate throttle lever several times and check discharge from pump jets before installing carburetor l Clean throttle body and intake manifold sealing surfaces 2 Install new insulator TRUCK SUPP SERVICE ENGINE FUEL 6M 25 GASKET Colored Surface To CARBURETOR Tl lt gt _ Manucl Brakes VIEW A INSULATOR Notch To Right Rear Fig 33 Carburetor and Choke Pipes V8 2Bbl Fig 34 Fuel Filter Replacement AIR HORN TIGHTENING SEQUENCE 3 Position carburetor over intake manifold and inst
334. etted paper element and a polywrap element The oil wetted paper element consists of an accordian pleated oiled paper filter supported by wire mesh with a VIEW A ENGINE OFF SNORKEL TUBE DIAPHRAGM VACUUM CHAMBER EE E M 5 LINKAGE DIAPHRAGM ZR f CONTROL DAMPER ASSM VIEW C UNDERHOOD TEMPERATURE ABOVE 128 F AIR BLEED VALVE OPEN DIAPHRAGM SPRING EL TUBE SNORKEL TUBE VACUUM CHAMBER AIR INLET a a TE CONTROL DAMPER ASSM HOT AIR PIPE LINKAGE DIAPHRAGM VIEW B UNDERHOOD TEMPERATURE SNORKEL TUBE SNORKEL TUBE plastisol seat on both top and bottom The polywrap element consists of the oil wetted paper element with an additional polyurethane band around it The air cleaner has an automatic air inlet temperature control device Air temperature is automatically controlled by a thermostatic valve which selects warmed air from the heat stove and or cooler air from the engine compartment or outside air inlet on some vehicles Fig 9C AIR BLEED VALVE CLOSED BELOW 85 F TEMP SENSING SPRING DIAPHRAGM SPRING VACUUM CHAMBER Ne 2 gt DIAPHRAGM x CONTROL DAMPER ASSM HOT AIR PIPE VIEW D UNDERHOOD TEMPERATURE AIR BLEED VALVE TEMP SENSING SPRING BETWEEN 85 F AND 128 F DIAPHRAGM SPRING VACUUM CHAMBER AIR INLET J 1 1 CONTROL DAMPE
335. f clean wood and hammer Fig 39 13 Position discharge cross over tube opening between a pair of Compressing Fixture bolts to permit access for feeler gage 14 Install top plate on Compressing Fixture J 9397 Tighten nuts to 15 Ib ft torque using 0 25 Ib ft torque wrench Gaging Procedure Steps 15 thru 18 The gaging operations which follow have been worked out on a simple basis to establish and provide necessary running tolerances Two gaging procedures are necessary The first is made to choose the proper size shoe discs to provide at each piston a 0016 to 0024 total preload between the seats and the axial plate at the tightest place through the 360 degree rotation of the axial plate at the tightest plate The bronze shoe discs are provided in 0005 variations including a basic ZERO shoe The second performed at the rear shaft thrust bearing and race pack is designed to obtain 0025 to 0030 preload between the hub surfaces of the axial plate and the front and rear hubs of the cylinder A total of 14 steel thrust races including a basic ZERO race are provided in increments of 0005 thickness to provide the required fit Feeler Gage Set J 9564 or J 9661 01 may be used for gaging proper shoe disc size Feeler Gage Set J 9564 01 or Dial Indicator Set J 8001 3 may be used to determine proper TRUCK SUPP OVERHAUL 1 16 AIR CONDITIONING COMPRESSOR L Fig 39 Assembling Cylinder Halves thrust r
336. f damage due to excessive heat the clutch plate and hub and pulley and bearing should be replaced Check further for the underlying cause of the damage i e low coil voltage coil should draw 3 2 amps at 12 volts or binding of the compressor internal mechanism clutch air gap too wide broken drive plate to hub asm springs etc Replace 1 Insert the square drive key into the hub of driven plate allow it to project approximately 3 16 out of the keyway 2 Line up the key in the hub with keyway in the shaft Fig 7 3 Position the Drive Plate Installer J 9480 1 on the threaded end of the shaft The Spacer J 9480 2 should be in place under the hex nut on the tool This tool has a left hand thread on the body Fig 8 4 Press the driven plate onto the shaft until there is approximately 3 32 space between the frictional faces of the clutch drive plate and pulley CAUTION Make certain key remains in place when pressing hub on shaft A ZERO thrust race is approximately 3 32 thick and may be used to roughly gage this operation Use Clutch Hub Holder J 25030 or J 9403 to hold clutch plate and hub if necessary 5 Install the hub spacer and using Snap Ring Pliers J 5403 21 install the retainer ring see installed Retainer Ring in inset of Fig 2 with convex side of ring facing spacer 6 Use Thin Wall Socket J 9399 and Clutch Hub Holder J 25030 or J 9403 to install a new shaft locknut with shoulder or cir
337. f external compressor components and disassembly and assembly of internal components must be performed on a clean workbench The work area tools and parts must be kept clean at all times Parts Tray J 9402 see Fig 33 should be used for all parts being removed as well as for replacement parts Although certain service operations can be performed without completely removing the compressor from the car the operations described herein are based on bench over haul with the compressor removed from the car They have been prepared in sequence in order of accessibility of the components Pad fender skirt and secure compressor near top of fender skirt with wire rope etc TRUCK SUPP OVERHAUL 1n vHB3AO 44 5 WONBL Jossajdwoy 9 v JO pepojdx3 O Ring Front Head Shaft Seal Assembly Switch Retainer Ring Seal Seat O Rings Seal Seat Retainer Ring Absorbent Sleeve Pressure Relief Valve Seal Retainer O Ring a O Ring O Ring Suction Screen Inner Oil Pump Gear Drain Plug Superheat Oil Pick up Tube Switch Ring Switch O Ring EN lock Nut Rear Head Outer Oil Pump Gear Rear Discharge Valve Plate Assembly Rear Suction Reed Bushing Needle Bearing O Ring Rear Cylinder Half Teflon Piston Ring Boll Shoe Disc Teflon Ring Type Piston Teflon Piston Ring Shaft Discharge Crossover Tube Thrust Races Clutch Coil Retainer Ring Compressor Shell Clutch Coi
338. f mainshaft and fasten with flange nut Torque nut to 100 foot pounds CAUTION See Caution on Page 1 of this section 10 BRAKES 5 9 Install cable assembly from back of flange plate Push retainer through hole in flange plate until tangs securely grip the inner side of the plate Place washer and reinforcement over the threaded end of anchor pin Hold anchor pin nut flat side against flange on flange plate in position behind flange plate and insert threaded end of anchor pin from front side Thread the anchor pin into nut and tighten securely 140 foot pounds torque Bend tang of washer over reinforcement and side of washer over hex of anchor pin CAUTION See Caution on Page 1 of this section Install lever on cable by compressing spring and inserting cable in channel of lever Release spring Install primary shoe short lining to lever as follows Place pin in lever place washer on pin and push pin through hole in primary shoe Fasten parts together by installing the clip in groove of pin CAUTION See Caution on Page 1 of this section Fasten two brake shoes and linings together by installing connecting spring Move the shoes toward each other and install adjusting screw Lubricate the flange plate contact surfaces with a very light coat of Delco Brake Lube 45450032 or equivalent Place shoe and linings in position on flange plate NOTE When facing the brake assem
339. fast idle cam follower lever to clear the steps of the fast idle cam At this point tension of the thermostatic coil will rotate the choke valve to the closed position and through rotation of the upper choke lever and movement of the choke rod the cam follower lever comes to rest on the high step of the fast idle cam During engine cranking the closed choke valve restricts air flow through the carburetor TRUCK SUPP SERVICE 6M 38 ENGINE FUEL THERMOSTATIC COIL INSIDE CUP VACUUM BREAK ADJUSTING SCREW VACUUM BREAK 26 Eo BAFFLE AM SECONDARY LOCKOUT LEVER FAST IDLE CAM FOLLOWER unc FAST TANG IDLE ADJUSTING SCREW CHOKE SYSTEM HOT AIR TYPE Fig 43 Choke System M4MC bores to provide a richer starting mixture When the engine starts and is running manifold vacuum applied to the front vacuum break diaphragm M4MC models or rear vacuum break diaphragm models opens the choke valve to a point where the engine will run without loading or stalling lean Vacuum break position As the choke unit temperature increases the fast idle cam follower will drop from the high step to the next lower step second step when the throttle is open On M4MC models engine vacuum supplied through an orifice in the choke housing pulls heat from the manifold heat stove into the housing and heat gradually relaxes choke coil tension which allows the choke valve to continue opening through
340. feeding from jet check pump discharge ball for proper seating by filling cavity above ball with fuel to level of casting No leak down should occur with discharge ball in place Restake or replace leaking check ball defective spring or retainer Clean carburetor or overhaul as necessary TRUCK SUPP SERVICE ENGINE FUEL 6M 17 Problem ENGINE HESITATES ON ACCELERATION Defective accelerator pump system 1 Remove air horn and check pump cup f cracked NOTE A quick check of the pump system can be made as scored or distorted replace the pump plunger follows With the engine off remove air cleaner and look 2 Check the pump discharge ball for proper seating and into the carburetor bores and observe pump stream while location The pump discharge ball is located in a cavity briskly opening throttle valve A full stream of fuel should next to the pump well To check for proper seating emit from pump jet and strike near the center of the remove air horn and gasket and fill cavity with fuel No venturi area leak down should occur Restake and replace check ball if leaking Make sure discharge ball spring and re tainer are properly installed Dirt in pump passages or pump jet Clean and Blow out with compressed air Fuel level Check for sticking float needle or binding float Free up or replace parts as necessary Check and reset float level as specified in carburetor overhaul section Leaking air horn to float b
341. flush with opening Fig 7F Installing Rear Output Housin N m REAR OUTPUT SHAFT HOUSING FRONT 14 Install differential carrier assembly on the input shaft Disassembly Carrier bolt heads should face rear of shaft 15 Position rear output shaft to differential carrier 1 Remove ring from rear output shaft housing front assembly load bearings in pinion shaft and discard 16 Install rear output housing front assembly gasket and 2 To remove roller bearings from housing insert a long retaining bolts drift through rear opening and drive bearing from 17 Install speedometer gear and shims approximately 050 housing Fig 6F Remove and discard rubber seal inch thickness on output shaft TRUCK SUPP OVERHAUL 18 19 20 Position rear output housing rear assembly to rear output housing front Be sure O ring is in proper position on front section of output housing NOTE Be sure vent is in upward position Install flange washer and retaining nut Leave nut loose approximately 060 inch until shim requirements are determined Install shim pack onto shaft in front of rear bearing to control end play to within 0 to 005 Hold rear flange and rotate front output shaft to check for binding of the rear output shaft 23 24 25 26 27 MANUAL TRANSMISSION 7M 21 Install speedometer driven gear in housing 22 Install lockout clutch shift rail poppet ball sp
342. fold vacuum is above approximately 5 6 Hg the vacuum break diaphragm system is seated However when the secondary valves are opened and manifold vacuum drops below the 5 6 point the spring in the vacuum break unit will force the diaphragm and stem off its seat The rate of movement of the seat is controlled by a restriction in the cover of the vacuum break unit When the diaphragm is seated it pulls the rod to the front end of the slot in the air valve shaft lever As the air valve starts to open when the secondary throttle valves are opened the restriction in the tube will restrict the air movement to the back side of the diaphragm and slow down the opening of the air valve AIR VALVE SHAFT LEVER P di p IR VALVE DASH ROD h se VACUUM BREAK DIAPHRAGM ASSEMBLY Fig 6Q Air Valve Dashpot Operation ee ACCELERATING PUMP SYSTEM FIG 7Q During quick acceleration when the throttle is opened rapidly the air flow and manifold vacuum change almost instantaneously The fuel which is heavier tends to lag behind causing a momentary leanness The accelerator pump is used to provide the extra fuel necessary for smooth operation during this time The accelerating pump system is located in the primary side of the carburetor It consists of a spring loaded pump plunger and pump return spring operating in a fuel well The pump plunger is operated by a pump lever on the air horn which is conn
343. fold vacuum to be applied to the auxiliary vacuum break diaphragm The diaphragm unit pulls the choke valve to a nearly open position overcoming choke coil tension At the same time the fast idle cam drops so that the fast idle cam follower tang rests on the lowest step of the fast idle cam This maintains some fast idle until the engine warms up When the engine is warmed up the choke coil pulls the choke valve fully open and the fast idle cam rotates so the fast idle cam follower tang drops off the low step at which point the engine will PRIMARY VACUUM BREAK DIAPHRAGM UNIT AUXILPARY VACUUM BREAK DIAPHRAGM UNIT Fig 8 Choke System Auxiliary Vacuum Break TRUCK SUPP SERVICE run at curb idle speed As the engine warms up the thermostatic coil is heated and gradually relaxes its spring tension so that air velocity through the air horn can continue to open the choke valve This continues until the engine is warm At this point the choke coil tension is completely relaxed and the choke valve is wide open The fast idle cam has graduated steps so that fast idle engine speed is lowered gradually during the engine warm up period The fast idle cam follows rotation of the choke valve When the choke valve is completely open and the engine is ENGINE FUEL 6M 7 warm the fast idle tang on the throttle lever will be off the steps of the fast idle cam At this point the idle stop solenoid controls normal engine idle speed An
344. for good engine starting The choke closing assist spring only exerts pressure on the vacuum break link to assist in closing the choke valve during engine starting When the engine starts and the vacuum break diaphragm seats the closing spring retainer hits a stop on the plunger stem and no longer exerts pressure on the vacuum break link to assist in closing the choke valve during engine starting On all models the secondary throttle valves are locked out during choke operation and the engine warm up period As the thermostatic coil warms up to the fully hot position the vacuum break lever allows the fast idle cam to drop down so that the cam follower is completely off the steps of the fast idle cam As the fast idle cam drops down it strikes the secondary throttle valve lock out pin This allows the secondary throttle valves to open for hot engine power requirements The choke system is equipped with an unloader mechanism which is designed to open the choke valve partially if the engine should become loaded or flooded To unload the engine the accelerator pedal must be depressed to the floor so that the throttle valves are held wide open A tang on a lever on the choke side of the primary throttle shaft contacts the fast idle cam and working through the intermediate choke shaft forces the choke valve slightly open This allows extra air to enter the carburetor bores pass into the engine manifold and cylinders to lean out the fuel into a
345. front combination of thrust races and bearing from shaft Discard races and bearing Examine surface of axial plate and shaft Replace as an assembly if necessary A certain amount of shoe disc wear on axial plate is normal as well as some markings indicating load of needle bearings on shaft Remove discharge cross over tube from cylinder half using self clamping pliers This is necessary only on original factory equipment as ends of the tube are swedged into cylinder halves The discharge cross over tube in internal mechanism assemblies that have been previously serviced have an O ring and bushing at EACH END of the tube and can be easily removed by hand see Fig 53 Examine piston bores and needle bearings in front and rear cylinder halves Replace front and rear cylinders if any cylinder bore is deeply scored or damaged Needle Bearing Installer J 9432 i Needle Bearing Fig 35 Installing Needle Bearing Needle bearings may be removed if necessary by driving them out with special Thin Wall Socket J 9399 Insert socket in hub end inner side of cylinder head and drive bearing out To install needle bearing place cylinder half on Support Block J 21352 and insert bearing in end of cylinder head with bearing identification marks UP Use Needle Bearing Installer J 9432 and drive bearing into cylinder head Fig 35 until tool bottoms on the cylinder face Two different width needle bearings
346. g 7 Power Steering Pump Fig 10 Power Steering Pump 305 350 400 8 10 30 Fig 8 Power Steering Pump Fig 11 Power Steering Pump TRUCK SUPP SERVICE 9 8 STEERING 454 V 8 MOTOR HOME orientate pressure hose when installing rotate pipe ends to rest against pump support lower yh cable and parking brake cable to be routed above power steering pipes and maintain clearance 250 OR 292 1 6 10 30 W EXCEPT HYDRABOOST Fig 14 Power Steering Hose Routing Rotate hose assembly against hydraboost housing assembly before tightening nut IS Sk 64 INCH MINIMUM CLEARANCE Rotate hose assembly against steering gear housing before tightening nut 292 1 6 G 30 VIEW B W HYDRABOOST Hose assembly must be installed against steering gear cover Fig 16 Power Steering Hose Routing P 20 30 W VACUUM POWER BRAKES Fig 17 Power Steering Hose Routing TRUCK SUPP SERVICE STEERING 9 9 Rotate hose assembly against hydraboost housing assembly lt before tightening nut GS f OF PUMP f EA VIEW A X Rotate hose assembly against steering gear housing before Y tightening nut 305 or 350 V 8 20 30 W POWER VACUUM VIEW 4 350 400 8 lt 64 MINIMUM BRAKES G 30 W HYDRABOOST CLEARANCE To orientate pressure Speedo cable and hose when installing parking brake rota
347. g carburetor 1 Clean throttle body and intake manifold sealing surfaces 2 Install new insulator o Position carburetor over intake manifold and install bolts Tighten bolts alternately to 144 in lbs Connect downshift cable and adjust as required Connect accelerator linkage Connect fresh air hose and choke hose to choke system Connect fuel and vacuum lines Install air cleaner wo Refer to Maintenance and Adjustment and check idle speed FUEL FILTER REPLACEMENT A plugged fuel filter will restrict fuel flow into carburetor and will result in a loss of engine power 1 Disconnect fuel line connection at inlet fuel filter nut 2 Remove inlet fuel filter nut from carburetor 3 Remove filter element and spring 4 Install element spring and filter element in carburetor 5 Install new gasket on inlet fitting nut and install nut in carburetor and tighten securely 6 Install fuel line and tighten connector AIR HORN TIGHTENING SEQUENCE Refer to figure 60 for proper air horn tightening sequence TRUCK SUPP SERVICE A F SH AIR HOSE GASKET COLORED ag STER SURFACE TO CARB CHOKE HOSE CHOKE PIPE 350 400 VB W HOT AIR CHOKE INSULATOR NCE TIGHTEN LONG BOLT 144 IN LBS THEN TIGHTEN SHORT BOLTS TO 144 IN LBS Fig 59 Carburetor and Choke Pipes V8 4Bbl ENGINE FUEL 6M 47 Fig 60 Horn Tightening Sequence TRUCK
348. g system is calibrated by tapered and stepped metering rods operating in metering jets and also through the main well air bleeds During cruising speeds and light engine loads manifold vacuum is high In this period the engine will run on leaner mixtures than required during heavy loads The primary main metering rods are connected to a vacuum responsive piston which operates against spring tension Engine manifold vacuum is supplied to a power piston through a vacuum channel When the vacuum is high the piston is held downward against spring tension and the larger diameter of the metering rod is in the main metering jet orifice This results in leaner fuel mixtures for economy operation s engine load increases and engine manifold vacuum drops spring pressure acting on the power piston overcomes the vacuum pull and gradually lifts the metering rods partially out of the main metering jets This enrichens the fuel mixture enough to give the desired power to overcome the added load Adjustable Part Throttle In order to provide a close tolerance adjustment in the main metering system an adjustment is provided to very accurately set the depth of the metering rods in the main metering jets The adjustment consists of a pin pressed in the side of the power piston which extends through a slot in the side of the piston well When the power piston is down economy position the side of the pin stops on top of a flat surface on the adjustme
349. ged battery and N to the negative terminal of the battery in THIS vehicle thus taking advantage of the flame arrestor feature on the battery in THIS vehicle should a spark occur 5 Start engine in the vehicle that is providing the jump start if it was not running Let run a few minutes then start the engine in the vehicle that has the discharged battery s n A i I 6 Reverse the above sequence EXACTLY when removing the jumper cables taking care to remove the cable from the negative terminal of the battery in THIS vehicle as the FIRST step PUSH STARTING TRUCKS WITH HEAVY DUTY EMISSION CONTROL SYSTEMS CAUTION Trucks equipped with light duty emission control systems must not be pushed or towed to start If your truck is equipped with a manual 3 speed or 4 speed transmission it can be started in an emergency by pushing When being pushed to start the engine turn off all unnecessary electrical loads turn ignition to ON depress the clutch pedal and place the shift lever in high gear Release the clutch pedal when speed reaches 10 to 15 miles per hour Bumpers and other parts contacted by the pushing vehicle should be protected from damage during pushing Never tow the truck to start TOWING All Except Four Wheel Drive Trucks Normally your vehicle may be towed with all four wheels on the ground for distances up to 50 miles at speeds of less than
350. gs 6i 9i 1 21 Position vacuum advance unit to housing and secure with two screws Position felt washer over lubricant reservoir at top of housing ENGINE ELECTRICAL 6Y 13 ADVANCE WEIGHT 2 N SPRING 2 Fig 7i Roll Pin Removal Lubricate felt wick with a few drops of motor oil and install replacement pole piece and plate assembly over upper bushing and vacuum advance unit Make sure the retainer bow that holds the white and green electrical leads together is color coded yellow Install lock ring pole piece and plate assembly 5 Place distributor shaft with rotor attached in distributor housing On 8 cylinder distributors install tanged washer shim and drive gear on distributor shaft On 6 cylinder distributors install drive gear on distributor shaft TRUCK SUPP SERVICE 6Y 14 ENGINE ELECTRICAL VACUUM UNIT ATTACHING SCREWS THIN C CAPACITOR WASHER PICKUP COIL LEADS ATTACHING SCREW MODULE CONNECTOR GROUND MODULE SCREW C Fig 8i Top View of Distributor Housing 8 Align holes of drive gear with hole of distributor shaft so that locating mark on drive gear is in line with tip of rotor Support distributor shaft on a wooden block or other suitable object and install roll pin Make sure distributor is supported in such a way that no damage will occur to distributor shaft while installing roll pin 9 Check to make sure shaft is not binding by spinning s
351. h the vent Slippage and transmission failure can result Fluid level too low can cause slipping particularly when the transmission is cold or the car is on a hill Check the transmission fluid level with engine running the shift lever in PARK and the car level NOTE If the vehicle has recently been operated for an extended period at high speed or in city traffic in hot weather or the vehicle is being used to pull a trailer an accurate fluid level cannot be determined until the fluid has cooled down usually about 30 minutes after the vehicle has been parked Remove the dipstick and touch the transmission end of the dipstick cautiously to find out if the fluid is cool warm or hot Wipe it clean and re insert until cap seats Remove dipstick and note readings e If the fluid feels cool about room temperature 65 F to 85 the level should be 1 8 to 3 8 inch below the ADD mark The dipstick has two dimples below the ADD mark to show this range e If it feels warm the level should be close to the ADD mark either above or below e If it feels hot cannot be held comfortably the level should be between the ADD and FULL marks 65 85 18 29 C COOL HOT ADD 1 PT WARM NOTE DO NOT OVERFILL It takes only one pint to raise level from ADD to FULL with a hot transmission TRUCK SUPP SERVICE AUTOMATIC TRANSMISSION DRAIN INTERVALS The transmission operating temperature resu
352. h in the float bowl IDLE SYSTEM Each bore of the Quadrajet carburetor has a separate and independent idle system to supply the correct air fuel mixture ratios during idle and off idle operation The idle system is used during this period because air flow through the carburetor venturi is not great enough to obtain efficient metering from the main discharge nozzles EGR EXHAUST GAS RECIRCULATION FIXED IOLE AIR BY PASS IDLE AIR BLEED IDLE CHANNEL RESTRICTION LOWER IDLE AIR BLEED gt TIMED AIN NOTE SIDE FUEL VACUUM PORTS TERING INLET TUBE MIXTURE per joiE NEEDLE PORT THROTTLE VALVE JOLE DISCHARGE HOLE W OFF IDLE OPERATION Fig 38 Idle System The idle system operates as follows During curb idle the throttle valves are held slightly open by the idle speed screw The small amount of air passing between the throttle valves and bores is regulated by this screw to give the engine the desired idle speed Since the engine requires very little air for idle and low speeds fuel is added to the air to produce a combustible mixture by the direct application of vacuum low pressure from the engine manifold to the idle discharge holes below the throttle valves With the idle discharge holes in a very low pressure area and the fuel in the float bowl vented to atmosphere high pressure the idle system operates as follows Fuel flows from the float bowl
353. haft a few times by hand 10 Position capacitor to housing and loosely install one mounting screw 11 Install connector to B and C terminals on module with tab on top 12 Apply special silicone lubricant liberally to bottom of module and secure with two screws 13 Position wiring harness with grommet in housing notch 14 Connect pink wire to capacitor stud and black wire to capacitor mounting screw Tighten screw 15 Connect white wire from pick up coil to terminal W module 16 Connect green wire from pick up coil to terminal G of module 17 Install centrifugal advance weights weight retainer dimple facing down and springs 18 Install rotor and secure with two screws CAUTION Notch on side of rotor must engage tab on cam weight base 19 Install distributor as described above Electronic Module Replacement Fig 8i The electronic module is serviced by complete replacement only When replacing the module a liberal coating of special silicone grease MUST be applied to the metal mounting surface on which the module will be installed If this grease is not applied the module will not cool properly which can cause the module to malfunction A tube of this special silicone grease is supplied with each replacement module 1 Raise hood and remove air cleaner 2 Release distributor cap and place aside in an out of the way place 3 Remove two screws and remove rotor from distributor shaf
354. haft assembly fig 10 tilt spline end of shaft downward and lift gear end upward and out of case 20 21 22 23 24 NOTE First and reverse sleeve and gear must pass through notch at right rear end of case Remove clutch gear through top of case Remove both shifter fork shafts fig 11R Remove countergear with tool in place thrust washers and roll pin Remove reverse idler gear and thrust washers by tapping shaft with hammer until end of idler gear shaft end with roll pin clears counterbore in rear of case and remove shaft fig 12R From the bottom of the case retrieve clutch shaft roller bearing or countergear needle bearing that may have fallen into case during disassembly MAINSHAFT DISASSEMBLY l Remove snap ring from front of output shaft and remove Second Third synchronizer assembly and second gear Mark hub and sleeve for correct assembly Remove snap ring and tabbed thrust washer from shaft and remove first gear and blocking ring Remove First Reverse hub retaining snap ring NOTE Observe position of spring and keys before removal also mark hub and sleeve for correct assembly Remove sleeve and gear spring and three keys from hub fig 13R Using an arbor press remove hub from output shaft CLEANING AND INSPECTION Transmission Case 1 Wash the transmission thoroughly inside and outside with cleaning solvent then inspect the case for cracks 2 Check the f
355. have the drive belt inspected for wear and tension every 24 months or 30 000 miles whichever occurs first In addition complete effectiveness of either system as well as full power and performance depends upon idle speed ignition timing and idle fuel mixture being set according to specification A quality tune up which includes these adjustments should be performed periodically to assure normal engine efficiency operation and performance EVAPORATION CONTROL SYSTEM E C S Every 24 months or 30 000 miles more often under dusty conditions the filter in the base of the canister must be replaced and the canister inspected EARLY FUEL EVAPORATION E F E SYSTEM First 7 500 miles or 6 months check valve for freedom of operation A binding condition must be corrected Check hoses for cracking abrasion or deterioration Replace parts as necessary AIR CLEANER CAUTION Do not remove the engine air cleaner unless temporary removal is necessary during repair or maintenance of the vehicle When the air cleaner is removed backfiring can cause fire in the engine compartment NOTE Under prolonged dusty driving conditions it is recommended that these operations be performed more often Replace the engine air cleaner element under normal operating conditions every 30 000 miles Crankcase Ventilation Filter Located Within Air Cleaner If so equipped inspect every oil change and replace if necessary Replace at least every 30
356. he compressor is installed R4 COMPRESSOR OVERHAUL GENERAL When servicing a compressor it is essential that steps be taken to prevent dirt or foreign material from getting on or into compressor parts and system during disassembly or reassembly of compressor Clean tools a clean workbench and a clean work area are very important for proper service The compressor connection areas and exterior of compressor should be cleaned off as much as possible prior to any on vehicle repairs or removing compressor for workbench service The parts must be kept clean at all times and any parts to be reassembled should be cleaned with clean solvent trichlorethylene or stoddard solvent and dried with dry air When necessary to use a cloth on any part it should be of a non lint producing type Refer to Figure 68 for the exploded view of the compressor parts and nomenclature When a compressor is removed from the vehicle for servicing the amount of oil remaining in the compressor should be drained through compressor suction discharge ports and measured This oil should then be discarded and new oil added to the compressor before compressor is again placed in operation on vehicle Refer to Figure 5 Section 1A of this manual for compressor oil charge If for any reason the R 4 compressor air conditioning hose assembly is removed from the compressor care must be taken to insure that the hose plate is fully seated to the compressor during re installat
357. he cross all of the time to check for free movement of the trunnions in the bearings If there seems to be a hang up stop pressing and recheck needle rollers to determine if one or more of them has been tipped under the end of the trunnion As soon as one bearing retainer groove clears the inside of the yoke stop pressing and snap the bearing retainer into place as shown in figure 9 Fig 9 Installing Snap Ring to Retain Trunnion TRUCK SUPP SERVICE 4 4 REAR SUSPENSION PROPSHAFT AND AXLE STRIKE TUBE YOKE EAR IN THIS AREA Fig 10 Seating Snap Rings 7 Continue to press until the opposite bearing retainer can be snapped into place If difficulty is encountered strike the yoke firmly with a hammer to aid in seating bearing retainers This springs the yoke ears slightly See figure 10 8 Assemble the other half of the universal joint in the same manner 9 Check the freedom of the rotation of both sets of trunnions of the cross If too tight again rap the yoke ears as described above This will loosen the bearings and help seat the bearing retainers PLACE ALIGNMENT KEY Fig 11 Alignment Key PROPSHAFT INSTALLATION CORRECT PHASING When reinstalling propshafts it is necessary to place the shafts into particular positions to assure proper operation This is called phasing Refer to procedures and illustrations on page 4 12 ofthe 1974 Light Duty Truck Service Manual For 1976 trucks three me
358. he edge of the float arm at the center rear Its purpose is to assist in lifting the float valve off its seat whenever fuel level in the float bowl is low CAUTION Do not place pull clip through small holes in top of float arm Severe flooding will result On some models no side windows are used in the float valve seat so that all fuel will be discharged over the top of the float valve seat to control fuel turbulence in the float bowl FLOAT NEEDLE INTERNAL VENT TUBE FLOAT NEEDLE INTERNAL VENT SLOT FLOAT HINGE PIN FUEL INLET FILTER NUT SIDE ENTRY FLOAT ASSEMBLY FLOAT BOWL RELIEF SPRING Fig 37 Float System The carburetor float chamber is internally vented by a vertical slot cast in the air horn located at the rear of the primary venturis and by a pressed in vent tube located in the air horn The purpose of the vertical vent slot and vent tube is to balance air pressure acting on the fuel in the float bowl with air flow through the carburetor bores In this way balanced air fuel ratios are maintained throughout all ranges of carburetor operation Also during periods of hot engine operation the vents are used to relieve vapor pressures that build up in the float bowl thereby preventing the pushing of raw fuel through the discharge nozzles into TRUCK SUPP SERVICE the engine to cause hard hot restarts An aneroid cavity insert is used in the float bowl The insert is used to reduce fuel slos
359. he right hand oil gallery fig 5 When oil temperature reaches 150 F the switch opens and shuts off vacuum to the EFE actuator On small block V8 and 454 V8 the EFE actuator is controlled by a thermal vacuum switch TVS located on the engine inlet manifold figs 3 and 4 When coolant temperature reaches 180 F the switch shuts off vacuum to the EFE actuator Without vacuum the vent on actuator opens internal spring in actuator pushes the diaphragm back to its at rest position and actuator rod opens the exhaust heat valve Spring loaded valve will remain open SERVICE PROCEDURES INSPECTION e Visually inspect exhaust heat valve for damage or binding linkage e Check that linkage is connected and vacuum hoses are properly routed and connected e Move exhaust heat valve by hand If binding or stuck free with manifold heat valve lubricant GM Part No 1050422 or equivalent If valve cannot be freed replace valve THERMAL VACUUM SWITCH TVS V8 Coolant Temperature The TVS is located on the engine coolant outlet housing or front of inlet manifold Replacement 1 Drain coolant below level of engine coolant outlet housing 2 Disconnect hoses at TVS ports 3 Remove TVS 4 Apply a soft setting sealant uniformly on replacement TVS male threads No sealant should be applied to sensor end of TVS 5 Install TVS tighten to 120 pound inches and then hand torque clockwise as required to align TVS to accomodate hose
360. he system and replace fuel filter as necessary If excessive dirt is found re move the carburetor unit Disassemble and clean 3 Check float needle and seat for proper seal If a needle and seat tester is not available apply mouth suction to the needle seat with needle installed If the needle is defective replace with a factory matched set 4 Check float for being loaded with fuel bent float hanger or binds in the float arm NOTE Check float for fuel absorption by lightly squeezing between fingers If wetness appears on surface or float feels heavy Check with known good float replace the float assembly 5 Adjust float as specified in carburetor overhaul section TRUCK SUPP SERVICE 6M 28 ENGINE FUEL Problem Engine does not have enough fast idle speed when cold Choke vacuum break unit is not adjusted to specification or unit is defective Choke coil rod out of adjustment Choke valve and or linkage sticking or binding Idle speed setting Not enough fuel in carburetor Carburetor flooding NOTE Also check carburetor flooding when engine cranks turn over but will not start or starts hard when cold OO F a rT x RR Re ENGINE STARTS AND STALLS Check and re set the fast idle setting and fast idle cam 1 Adjust vacuum break to specification 2 If adjusted O K check the vacuum break for proper operation as follows On the externally mounted vacuum break unit connect a piece of hose to
361. hms If a resistance either above or below the value indicated is shown the main wiring harness should be replaced NOTE When disconnecting or reconnecting the main wiring harness connector from the Regulator care should be exercised so as not to damage the blade connectors or the wiring harness The disconnect may be facilitated by prying carefully on the plastic connector with a small screwdriver Measuring the solenoid coil circuit resistance between point E Hold Terminal and ground the ideal resistance should be between 5 and 6 ohms A reading of less than 4 ohms indicates shorting in the coil circuit A reading of more than 7 ohms indicates excessive ACCESSORIES 15 7 resistance in the coil circuit Either extremity indicates replacement of the Regulator assembly The main harness wiring from point F to G white wire should also be checked for continuity Servo and Vacuum System Test To determine the condition of the diaphragm remove hose from the Servo Unit and apply 14 inches of vacuum to the tube opening and hold in for one minute The vacuum shall not leak down more than 5 inches of vacuum in one minute If leakage is detected replace the Servo To utilize engine as a vacuum source proceed as follows l Disconnect Servo cable at carburetor and vacuum hose from the Servo then connect engine vacuum directly to the Servo fitting 2 Note position of Servo diaphragm 3 Start engine the diaphragm sho
362. hs or 3 000 miles when the vehicle is operated under the following conditions a driving in dusty conditions b trailer pulling c extensive idling or d short trip operation at freezing temperatures with engine not thoroughly warmed up See elsewhere in this Section for additional details on engine oil Replace at the first oil change and every other oil change thereafter 5 TIRES equalize wear rotate tires as illustrated in Section 10 of this Manual and adjust tire pressures A 6 REAR AXLE Change lubricant at first 15 000 miles on Positraction axles Change lubricant every 7 500 miles on all type rear axles or final drives when using vehicle to pull a trailer A 7 AIR CONDITIONING Check condition of air conditioning system hoses and refrigerant charge at sight glass if so equipped Replace hoses and or refrigerant if need is indicated A 8 COOLING SYSTEM At 12 month or 15 000 mile intervals wash radiator cap and filler neck with clean water pressure test system and radiator cap for proper pressure holding capacity tighten hose clamps and inspect condition of all cooling and heater hoses Replace hoses if checked swollen or otherwise deteriorated Also each 12 months or 15 000 miles clean exterior of radiator core and air conditioning condenser Every 24 months or 30 000 miles drain flush and refill the cooling system with a new coolant solution A 9 WHEEL BEARINGS Clean and repack front whee
363. hydrocarbon emissions With exception of the pipe installation which is included in this section refer to the 1974 Light Duty Truck Service Manual for service procedures Early Fuel Evaporation EFE System is designed to produce a very short engine warm up cycle to improve vehicle driveability and reduce exhaust emissions Service procedures are included in this section HEAVY DUTY EMISSIONS The following emission control systems are used on a light duty truck with heavy duty emissions Positive Crankcase Ventilation PVC Withdraws oil vapor and gas vapor from the various cavities throughout the engine for burning in all combustion cycle Refer to 1974 Light Duty Truck Service Manual for service procedures TRUCK SUPP SERVICE 6T 2 EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation EGR California with 454 V8 Meters exhaust gas into induction system for recirculation through the combustion cycle to reduce oxides of nitrogen emissions Refer to 1974 Light Duty Truck Service Manual for service procedures Evaporation Control System ECS California Vehicle Controls emission of gasoline vapor to the atmosphere by means of an integral separator with the fuel tank that separates vapor from liquid fuel a filler cap that doesn t permit venting into the atmosphere a canister for storage of vapors lines hoses and valves to control and transport vapors from fuel tank to storage and finally to the carburetor for utili
364. icate BOTH ENDS of the piston with 525 viscosity refrigerant oil before inserting the piston into the cylinder bore AIR CONDITIONING COMPRESSOR 1 19 TEFLON RING TEFLON RING Fig 48 Teflon A 6 Piston Ring Installed in Piston Groove CAUTION Reasonable care should be exercised in installing the piston into the cylinder bore to prevent damage to the Teflon ring A 6 COMPRESSOR INTERNAL MECHANISM Assembly After properly performing the Procedure choosing the correct shoe discs and thrust races and installing any needed Teflon Piston Rings the cylinder assembly may now be reassembled Be sure to install all NEW seals and O rings All are included in the compressor TRUCK SUPP OVERHAUL 1 20 AIR CONDITIONING COMPRESSOR PISTON AND RING ASSEMBLY NOTCHED END J 24608 1 PISTON RING GAGE Fig 50 Gaging Piston Ring Size O Ring Service Kit Assembly procedure is as follows 1 Support the FRONT half of the cylinder assembly on Compressing Fixture J 9397 Install the shaft and axial plate threaded end down with its front bearing race pack ZERO race bearing NUMBERED race if this was not already done at the end of the Procedure Apply a light smear of petroleum jelly to the numbered shoe discs chosen in the gaging procedure and install all balls and shoe discs in their proper place in the piston assembly Rotate the axial plate so that the high point is above cyli
365. ice window regulators and controls are confined in the space between the upholstery and the outside door panel Easy access to the working parts may be made by removing the trim Door weatherstrips and rubber hood bumpers should be lightly coated with a rubber lubricant UNDERBODY MAINTENANCE The effects of salt and other corrosive materials used for ice and snow removal and dust control can result in accelerated rusting and deterioration of underbody components such as GENERAL INFORMATION AND LUBRICATION 0 11 brake or pan exhaust system brackets parking brake cables These corrosive effects however can be reduced by periodic flushing of the underbody with plain water In geographic areas having a heavy concentration of such corrosive materials it is recommended that the complete underbody be inspected and flushed at least once a year preferably after a winter s exposure Particular attention should be given to cleaning out underbody members where dirt and other foreign materials may have collected SPEEDOMETER ADAPTER On vehicles so equipped lubricate adapter at fitting with water resistant EP chassis grease which meets General Motors Specification GM 6031 M every 7 500 miles TRUCK SUPP SERVICE 0 12 GENERAL INFORMATION AND LUBRICATION COMPLETE VEHICLE MAINTENANCE SCHEDULE When To Perform Services Services Months or Miles Whichever Occurs First For Details See Numhered Paragraphs Eve
366. ice joint bearing cups It usually is easier to remove plastic if a small pin or punch is first driven through the injection holes 6 If the front universal joint is being serviced remove the pair of bearing cups from the slip yoke in the same manner Reassembly universal joint service kit is used when reassembling this joint See figure 7 This kit includes one pregreased cross assembly four service bearing cup assemblies with seals needle rollers washers grease and four bearing retainers Make sure that the seals are in place on the service bearing cups to hold the needle rollers in place for handling ROLLER BEARINGS BEARING RETAINER BEARING CUP FLAT PLASTIC ROUND PLASTIC WASHER Fig 7 Repair Kit REAR SUSPENSION PROPSHAFT AND AXLE 4 3 Fig 8 Installing Trunnion into Yoke Remove all of the remains of the sheared plastic bearing retainers from the grooves in the yokes The sheared plastic may prevent the bearing cups from being pressed into place and this could prevent the bearing retainers from being properly seated Install one bearing cup part way into one side of the yoke and turn this yoke ear to the bottom Insert cross into yoke so that the trunnion seats freely into bearing cup as shown in figure 8 Install opposite bearing cup part way Make sure that both trunnions are started straight and true into both bearing cups Press against opposite bearing cups working t
367. iciencies should be brought to the attention of your dealer or another service outlet as soon as possible so the advice of a qualified mechanic is available regarding the need for repairs or replacements e 2 inl STEERING COLUMN LOCK Check for proper operation by attempting to turn key to LOCK position in the various transmission gear range when the vehicle is stationary Key should turn to LOCK position only when transmission control is in PARK on automatic transmission models or in reverse on manual transmission models Key should be removable only in LOCK position PARKING BRAKE Check parking brake holding ability by parking on a fairly steep hill and restraining the vehicle with the parking brake only CAUTION Before making checks c or d below be sure to have a clear distance ahead and behind the vehicle set the parking brake and firmly apply the foot brake Do not depress accelerator pedal Be prepared to turn off ignition switch immediately if engine should start STARTER SAFETY SWITCH AUTOMATIC TRANSMISSION VEHICLES Check starter safety switch by attempting to start the engine with the transmission in each of the driving gears The starter should operate only in the Park P or Neutral N positions STARTER SAFETY SWITCH MANUAL TRANSMISSION VEHICLES To check place the shift lever in neutral depress the clutch halfway and attempt to start The starter should operate only when
368. ied to diaphragm and distributor vacuum and EGR connected 1500 rpm for throttle return control system with vacuum applied to diaphragm and distributor vacuum and EGR connected TORQUE SPECIFICATIONS 1 Carburetor 2GC Carburetor Torque Screw in Ibs THROTTLE BODY Throttle Body to Bowl 72 BOWL Cluster Fast Idle Cam Metering Jet CHOKE HOUSING Choke Lever Choke Hsg to Throttle Body Choke Housing Cover AIR HORN Air Horn to Bowl Vacuum Break Unit Choke Shaft Fuel Inlet Nut Needle Seat Air Horn to Bowl Air Cleaner Bridge Throttle Body to Bowl Needle Seat Metering Jet Fuel Inlet Nut Fast Idle Cam Choke Lever Pump Lever Loctite AVV or equivalent M4MC M4ME Carburetor THROTTLE BODY Throttle Body to Bowl CHOKE HOUSING Choke Lever Choke Housing Attaching 4MV Carburetor Choke Housing Cover AIR HORN Air Horn to Bowl 10 32 Air Horn to Bowl 8 32 Air Horn to Throttle Body Choke Lever Vacuum Break Unit Fuel Inlet Nut Needle Seat Metering Jet Solenoid Bracket Air Horn to Bowl 10 32 Air Horn to Bowl 8 32 Air Horn to Throttle Body Throttle Body to Bowl Vacuum Break Unit Solenoid Bracket Fuel Inlet Nut Metering Jet Needle Seat TRUCK SUPP SPECS SPECIFICATIONS 17 ENGINE ELECTRICAL SECTION 6Y STARTING MOTOR Model No Application 1108779 C amp K 10 250 L 6 LD4 G Van No 3573 2300 Watts 3573 2300 Watts Free Speed Amp
369. ief Valve Shipping Plate Retaining Ring Valve Plate Assy Cylinder and Shaft Assy Cap Thrust Washer Belleville Washer O Ring Shell Assy Ring Seal Main Bearing Front Head Assy Screw and Washer Assy O Ring Shaft Seal Seal Seat Retaining Ring Fig 3 Radial Four Cylinder Compressor Exploded View When the system is in MAX A C mode and the temperature lever is at full COLD the air inlet door is positioned to reduce the supply of outside air from approximately 100 percent to approximately 20 percent The remainder of the air input 80 percent to the A C system is then taken from the interior of the passenger compartment This recirculation of interior air recirc operation provides source of fast cool down of interior temperatures A switch connected to the selector lever overrides the blower FAN switch in MAX A C and automatically provides high blower speed Temperature Control Lever The temperature lever determines the temperature of outlet airflow by positioning the temperature door in the selector duct assembly through the motion of a bowden cable linking the control panel lever to the temperature door NOTE An engine thermal switch prevents LO blower operation until the temperature at the switch reaches 95 F This blower delay can be by passed by placing TRUCK SUPP SERVICE SPECIAL STUD FOR BATTERY GROUND Fig 4 Compressor mounting
370. ign cotter pin Not to exceed 90 ft lbs maximum Plus additional torque to align cotter pin Not to exceed 130 ft lbs maximum Plus additional torque to align cotter pin Back nut off to align cotter pin at nearest slot specifications are given in foot pounds of Torque unless indicated otherwise C10 610 20 Rubber Bushings C20 30 G30 P10 30 Steel Bushings FOUR WHEEL DRIVE Gear Backlash Preferred Used Pinion Bearing Preload 55004 Dana Min and Max 004 009 MERC A EM eS MEE pe Ring Gear Differential Bearing Caps Filler Plugs Drive Pinion Nut Brake Backing Plate Bolt Torques Ft Lbs TRUCK SUPP SPECS SPECIFICATIONS 6 REAR SUSPENSION SECTION 4 REAR WHEEL BEARING ADJUSTMENT SPECIFICATION Adjusting Nut Back off Ring Gear Size Bearing Adjusting Nut Torque 10 1 2 and 9 3 4 50 Ft Lbs Outer Locknut Torque 65 Ft Lbs 001 10 Resulting Bearing Adjustment End Play Type of Bearing 010 Tapered Roller 12 1 4 90 Ft Lbs Back off nut and retighten to 35 Ft Lbs then back off With wheel rotating UNIVERSAL JOINT ATTACHMENT TORQUE SPECIFICATIONS 15 Ft Lbs Strap Attachments U Bolt Attachment 20 Ft Lbs 250 Ft Lbs nut 1 4 turn Ring Gear Size 8 1 2 8 7 8 Slight Preloaded Barrel Roller Lubricant Capacity 4 2 Pint
371. in Open Installed Height 1 32 Free Length 55 640 1 66 85 936169 180 192 1 27 174 184 1 30 Valve Spring Outer 1 21 32 1 5 8 1 5 8 1 23 32 1 7 8 Approx of Coils TRUCK SUPP SPECS SPECIFICATIONS 11 TUNE UP CHART ENGINE In Line V8 Displacement 250 292 350 _ 454 COMPRESSION 130 psi 150 psi SPARK Make amp AC R46TS AC R44T AC R45TS PLUG Number Gap 35 035 045 SEE IGNITION SPECIFICATIONS DISTRIBUTOR no DRIVE 5 and Air Pump BELT A C Compressor 65 lbs Min 95 5 lbs Used 140 5lbs Strand Tension Gau AIR CLEANER Refer to Section 0 of this Manual VALVE LASH Hydraulic 1 turn down from zero lash IDLE RPM Refer to Exhaust Emission Tune Up Label FUEL 3 1 2 to 4 1 2 7 to 8 1 2 PUMP 50 lb Min 75 5 lbs Used 125 5 lbs New Using Strand Tension Gauge e Pressure in lbs 1 pint 30 45 seconds cranking speed Volume CRANKCASE VENTILATION Refer to Section 0 of this Manual PSI At Cranking Speed throttle wide open Maximum variation 20 PSI between cylinders 2 At idle speed with vacuum advance line disconnected and plugged On Step Van vehicles use number two cylinder and timing tab on bottom of cover S Do not pry against A LR pump housing CAUTION In addition to i
372. ing and cover Fig 29 20 Examine internal mechanism for any obvious damage If internal mechanism has sustained major damage due to loss of refrigerant or oil it may be necessary to use the Service internal mechanism Assembly rather than replace individual parts INTERNAL MECHANISM Disassembly Use Parts Tray J 9402 Fig 33 to retain compressor parts during disassembly 1 Remove internal mechanism from compressor as described in Compressor Internal Mechanism Removal procedure TRUCK SUPP OVERHAUL SUCTION PASS COVER CYLINDER ASSEMBLY Fig 29 Removing Suction Cross Over Cover SUPPORT BLOCK J 21352 Fig 30 Piston and Cylinder 2 Identify by pencil mark or some other suitable means each piston numbering them as 1 2 and 3 Fig 30 Number the piston bores in the front cylinder half in like manner so that pistons can be replaced in their original locations Separate cylinder halves using a wood block and mallet Fig 31 Make certain that discharge cross over tube does not contact axial plate when separating cylinder halves a new Service discharge cross over tube will be installed later CAUTION UNDER NO CIRCUMSTANCES SHOULD SHAFT BE STRUCK AT EITHER END in an effort to separate upper and lower cylinder halves because the shaft and the axial plate could be damaged 4 AIR CONDITIONING COMPRESSOR 1 13 PISTON FRONT END Fig 32 Notch Iden
373. ing is positively controlled CABLE ASSEMBLY NOTE Cable is not to be kinked or damaged in any way during assembly 5 SPRING OUTER hh SPRING INNER FASTENER NOTE With Inner Spring inside Outer Spring anchor both Springs thru hole in Carburetor Lever and holes in Support Bracket Fig 4C Accelerator Controls V8 4Bbl REINFORCEMENT TIGHTEN TO 25 POUND INCHES Fig 5C Accelerator Pedal CK CAUTION Care must be used in pressing Retainer into hole in Rod to assure Cable RETAINER is not kinked or damaged in any w y A LA CABLE ASSEMBLY 7 x db TIGHTEN TO 27 IN LBS SPRING SHOWN IN LOADED POSITION Fig 6C Accelerator Pedal G NOTE Slip accelerator control cable thru slot in rod Install retainer being sure it is seated CABLE RETAINER CAUTION Care must be used in pressing the retainer into hole in rod to assure cable is not kinked or damaged in any way REINFORCEMENT EN ACCELERATOR CONTROL CABLE PIN SS 42 IN LBS TIGHTEN TO Fig 7C Accelerator Pedal P42 TRUCK SUPP SERVICE ENGINE FUEL 6M 67 5 Nichten TO 50 IN LBS Fig 8C Accelerator Pedal P32 AIR CLEANER GENERAL Air cleaner operates primarily to remove dust and dirt from the air that is taken into the carburetor and engine The air cleaner is also effective in reducing engine air inlet noise Two types of air cleaner elements are used on trucks an oil w
374. ing is pressed into the rotor hub and held in place by three punch stakes 120 apart into the rotor hub near the hub bore The entire clutch coil pulley rim rotor and bearing assembly is pressed on the front head of the compressor and secured by a retainer ring When power is supplied to the clutch coil the armature plate of the drive plate and hub assembly electromagnetically engages the slotted portion of the rotor face which then drives the crankshaft through the drive plate leaf springs and hub Shaft Seal The main shaft seal located in the neck of the compressor front head consists of the seal assembly with its ceramic seal face in a spring loaded cage An O ring seal located within the ceramic seal provides a seal to the shaft surface The contact surface of the shaft seal seat is finished to a high polish and must be protected against nicks scratches and even fingerprints Any surface damage will cause a poor seal An O ring located in an internal groove in the neck of the front head provides a seal with the outer diameter of the seal seat A retainer ring tapered side away from the seat secures the seat in place The hub and armature plate must be removed to gain access to the seal A shaft seal kit HEATER AND AIR CONDITIONING 1A 3 contains all necessary replacement parts for field service Front Head The front head contains the front main shaft bearing pressed in place and a drilled oil hole for lubrication t
375. ing wheel and turn off the engine Depress and release the brake pedal There should be a minimum of three power assisted brake applications before a hard pedal is obtained Restart the engine and turn the steering wheel until the wheels contact the wheel stops lightly There should be a light hissing sound as the accumulator is charged Hold steering wheel lightly against stop for a maximum of five seconds Then release the steering wheel and turn off the engine Wait ane hour and apply brake pedal do not re start the engine There should still be a minimum af three power assisted brake applications before obtaining a hard pedal If either of these preliminary checks shows that the accumulator is not holding its charge the trouble may be one af the following causes Probable Cause Remedy OE EOEDDMLLLLLLLLLE 1 External leakage at accumulator welds 1 Replace booster assembly 2 Internal leakage in accumulator past 2 Replace booster piston seal or relief valve 3 Replace all booster seals and 3 Internal leakage at booster accumulator accumulator valves valve if accumulator is not leaking externally or internally TRUCK SUPP SERVICE SECTION 6 ENGINE CONTENTS OF THIS SECTION Engine T ne Up E recie aree a a 6 1 Engine Mechanical 6 2 Diagnosis m Pa aa u S et
376. inkage and Suspension 0 10 GIOVeFTIOE eiie i eai 0 8 Hood Latch and Hood 0 10 Accelerator Linkage eee 0 8 Body E brication 4i cese erem eint 0 10 Automatic Transmission Fluid Recommendations 0 8 Speedometer Adapter eee 0 11 Manual Transmission eene 0 9 Complete Maintenance Schedule 0 12 Transmission Shift Linkage 0 9 Lubrication Diagrams eJ m 0 9 Conventional Models sss 0 19 Rear Axle 1 2 Ton G Models 4 eti Ere 0 20 re 0 9 MAINTENANCE SCHEDULE separate maintenance folder has been provided with each vehicle which contains a complete schedule and brief explanation of the safety emission control lubrication and general maintenance it requires The maintenance folder information is supplemented by this section of this manual as well as the separate vehicle and emissions warranty booklet also furnished with each vehicle Read all three publications for a full understanding of vehicle maintenance requirements The time mileage intervals for lubrication maintenance services outlined in this section are intended as a general guide for establishing regular maintenance and lubrication periods for trucks with light duty emission control sy
377. ion Fuel is drawn into the pump well through the inlet check ball on the upward stroke of the pump plunger Downward motion of the pump plunger as on acceleration seats the aluminum inlet check ball and forces the fuel through the pump discharge passage where it unseats the pump discharge ball and passes on through to the pump jets where it sprays into the venturi area An expander spring located beneath the pump cup ensures good contact between the lip of the pump cup and the pump well at all times When the pump is not in operation the pump cup unseats from the plunger head and acts as a vent for the pump well If vapors form in the pump well during hot operation they are vented between the head and pump cup out into the fuel bowl Without this pump vent vapor pressure in the pump well might force fuel from the pump system into the engine manifold causing hard starting when the engine is hot The pump discharge ball in the accelerator pump passage prevents any pump pull over or discharge of fuel from the pump nozzles when the accelerator is inoperative OPERATION OF CHOKE SYSTEM Fig 26 The model 2GC carburetor has an integral choke housing and thermostatic coil assembly mounted on the carburetor throttle body The choke system operates as follows ENGINE FUEL 6M 21 UPPER CHOKE VACUUM BREAK CHOKE SHAFT LEVER CHOKE VALVE CHOKE ROD INTERMEDIATE CHOKE THERMOSTATIC CHOKE COIL amp UNLOADER
378. ion Should the plate be cocked and the retainer bolt driven metal flanges in the O Ring cavities could damage the seal surface of the compressor Some service operations can be performed without disturbing the internal mechanism completely removing the compressor from vehicle or discharging the system Among them are replacement of the clutch drive plate and hub assembly clutch rotor and bearing assembly and clutch coil and pulley rim where on vehicle space permits The system must be discharged evacuated and charged to replace the compressor shaft seal pressure relief valve and superheat switch whether the compressor is removed from vehicle or not See Evacuation and Charging Procedure The service operations shown in the following procedure are based on bench overhaul with compressor removed from vehicle For those operations possible to be performed with compressor on the vehicle the procedure is essentially the same The procedures are basically in order of the normal sequence of removal for the accessibility of the components When necessary to adjust the compressor belt tension DO NOT pry on the compressor shell lift at square hole on the compressor mounting bracket It is recommended that compressor holding fixture 1 295008 1 Fig 69 be used for all workbench procedures to keep the compressor assembly off the workbench and help prevent any possible dirt contamination of parts The compressor holding fixture may b
379. ion for the sliding side load door and rear load doors EMERGENCY STARTING e Engines in vehicles with automatic transmissions cannot be started by pushing or towing the vehicle Never tow or push trucks equipped with light duty emission control systems to start engine A vehicle with a discharged battery may be started by transferring electrical power from a battery in another car called jump starting Jump Starting Jump starting may be dangerous and should be attempted only if the following three conditions are met If they are not we strongly recommend that you leave the starting to a competent mechanic TRUCK SUPP SERVICE 0 4 GENERAL INFORMATION AND LUBRICATION The battery in the OTHER vehicle must be 12 volt and negatively grounded like the one in THIS vehicle Check the other vehicle s owner s manual to see if it 1s e The battery in THIS vehicle must be equipped with flame arrestor vents like the original equipment Delco Freedom battery or flame arrestor type filler vent caps e Ifthebattery is a Delco sealed type battery without filler opening or caps its charge indicator must be dark with or without green dot showing Do NOT attempt jump starting if the charge indicator has a light or bright center CAUTION Departures from these conditions or the procedure below could result in 1 serious personal injury particularly to eyes or property damage from such causes as battery explosion
380. ire much force on wrench if the screws are kept in step while turning The shell can be removed by hand as soon as shell is free of shell to cylinder O rings Do not turn screws any further than necessary to release shell PISTON AND REED ASSEMBLY 4 Remove compressor shell remove holding fixture 1 25008 1 from compressor reverse fixture to again hold compressor by the opposite side using the short length screws At this point the valve plate retainer ring may be removed using internal snap ring pliers J 4245 Fig 93 and remove the compressor valve plate Fig 94 for replacement or piston inspection Fig 94 Inspecting Piston and Reed Assembly Installation 3 Dip remaining cylinder to shell O ring in oil and 1 Remove old cylinder to shell O rings and discard O timc groove ol collider Check compressor assembly and interior of compressor shell to be sure they are free of lint or dirt 4 Place compressor shell on cylinder and rotate retaining 2 Dip a cylinder to shell O ring in 525 Viscosity oil and strap to its original location Fig 92 install in rear O ring groove of cylinder Be careful in moving O ring across cylinder surface to prevent damaging O ring Attach shell installing fixture J 25008 2 to the holding fixture J 25008 1 using the long bolts and plate washers of tool set TRUCK SUPP OVERHAUL Ag A Y 2 m ww Fig 95 Installing Shell Assemb
381. iring Ignition P MODELS AND 1 TON 5 ON CHASSIS switch must be in OFF position FRAME MOUNTED TANKS Refer to the 1974 Service Manual for 30 gallon fuel tank mounted on a P20 or P30 model Refer to Figure 1 for a 50 gallon fuel tank mounted on a P30 model 4 Remove bolts attaching tank supports to frame 5 Remove tank complete with mounting brackets and support straps 6 Remove tank from brackets and support straps if Removal and Installation necessary 7 To install reverse the removal procedures Replace all 1 Drain tank anti squeak material 2 Remove filler neck FUEL FEED AND VAPOR PIPES Fuel pipes are secured to the underbody with clamp and screw assemblies Flexible hoses are located at fuel tank fuel vapor and return lines and fuel pump The pipes should be inspected occasionally for leaks kinks or dents If evidence of dirt or foreign material is found in carburetor fuel pump or pipes pipe should be disconnected and blown out Dirt or foreign material may be caused by a damaged or omitted fuel strainer in fuel tank Replacement If replacement of a fuel feed pipe vapor pipe or return pipe is required use only double wrap and brazed steel tubing meeting GM Specification 123M or its equivalent Under no condition use copper or aluminum tubing to replace steel tubing Those materials do not have satisfactory fatique durability to withstand normal vehicle vibrations Repair 1 Do not use fuel hos
382. istortion of tension spring and or metering rods Note carefully position of tension spring for later or center plastic eccentric cam a repair kit is available reassembly Instructions for assembly are included in the repair kit PUMP GASKET PLUNGER 7 PLASTIC FILLER BLOCK Fig 7MQ Removing Front Vacuum Break Fig 8MQ Removing Air Horn Gasket and Pump Plunger TRUCK SUPP OVERHAUL 6M 14 CARBURETOR Fig 9MQ Removing Power Piston and Metering Rods 6 Remove plastic filler block over float valve 7 Remove float assembly and float needle by pulling up on retaining pin Remove float needle seat and gasket Fig 11MQ 8 Remove aneroid cavity insert from float bowl Fig 12MQ 9 Remove primary main metering jets Fig 13MQ T NOTE No attempt should be made to remove the secondary metering orifice plates These jets are fixed and if damaged bowl replacement is required 10 Remove pump discharge check ball retainer and check ball RETAINING SPRING METERING ROD POWER PISTON POWER PISTON SPRING Fig 10MQ Power Piston and Metering Rods RETAINING PIN FLOAT ASSEMBLY Fig 11MQ Float Assembly M4ME Model With Rear Vacuum Break Remove hose from rear vacuum break control assembly Remove two screws from rear vacuum break bracket and rotate the assembly to remove vacuum break rod from slot in plunger head Fig 14MQ CAUTION Do not place vacuum break assembly in
383. istributor cap connector is a tach terminal Connect the tachometer to this terminal and to ground Some tachometers must connect from the tach terminal to the battery positive terminal Follow tachometer manufacturer s instructions CAUTION Grounding tach terminal could damage the HEI electronic module Other Test Equipment Oscilliscopes require special adaptors Distributor machines require a special amplifier The equipment manufacturers have instructions and details necessary to modify test equipment for HEI diagnosis Vacuum and Centrifugal Advance Specifications Vacuum and centrifugal advance specifications are listed in the Specifications Section of this manual Distributor Removal 1 Disconnect wiring harness connectors at side of distributor cap 2 Remove distributor cap and position out of way 3 Disconnect vacuum advance hose from vacuum advance mechanism 4 Scribe a mark on the engine in line with rotor Note approximate position of distributor housing in relation to engine TRUCK SUPP SERVICE 5 6 Remove distributor hold down nut and clamp Lift distributor from engine installation l Install distributor using same procedure as for standard distributor Install distributor hold down clamp and snugly install nut Move distributor housing to approximate position relative to engine noted during removal Position distributor cap to housing with tab in base of c
384. ith a simple adjustment of the orifice tube in the regulator see fig 2C CAUTION Never remove orifice tube from casting It cannot be reinstalled once it has been removed 1 To check cruise speed error engage Cruise Master at 60 mph 2 If vehicle cruises below engagement speed screw orifice tube outward 3 If vehicle cruises above engagement speed screw orifice tube inward wo E oH or MN CARB P 4 4 Sgait CARB LSP ever LEVER A view EW LF 1 4 159 a x DEAS yt Fig 3C Regulator and Brackets G Truck NOTE Each 1 4 turn of the orifice tube will change cruise speed approximately one mph Snug up lock nut after each adjustment If a Regulator is found to be defective and not simply out of adjustment it must be replaced During replacement check the hoses which connect to the Regulator and replace any which are cracked or deteriorated SERVO UNIT FIG 4C Before adjusting the Servo Cable make sure the carburetor is set at its lowest idle throttle position by manually setting the fast idle cam at its lowest step with the ignition switch TRUCK SUPP SERVICE 15 4 ACCESSORIES OFF Adjust the cable so there is as little lost motion at the Servo as possible see Fig 4C If the Servo Unit is found to be defective replacement is required Note the condition of the hoses and replace any which are cracked or deteriorated BRAKE RELEASE SWITCHES
385. ith slot on pump plunger lever Remove the link 9 Remove pump assembly from float bowl 10 Remove pump return spring and power piston spring from float bowl 11 Remove T guide and pump discharge spring using needle nose pliers 12 Pump discharge ball and idle tube can be removed at the same time by inverting the bowl 13 Remove main metering jet from bottom of fuel bowl 14 Remove float needle seat and gasket 15 Remove two screws from idle compensator cover A T only Then remove cover hot idle compensator and seal from recess in bowl 16 The idle stop solenoid can be removed at this time if desired 17 Remove the fuel inlet nut and gasket then remove the filter and relief spring No further disassembly of the float bowl is required Throttle Body Fig 6 1 Invert carburetor bowl on bench and remove two throttle body to bowl attaching screws and lockwashers Throttle body and insulator gasket may now be removed CARBURETOR 6M 3 PUMP DISCHARGE SPRING Fig 5b Removing Pump Discharge Spring 2 No further disassembly of the throttle body is necessary unless the idle mixture needle is damaged or the idle channels need cleaning If necessary to remove the idle mixture needle cut the tang from the plastic limiter cap Do not install a replacement cap as a bare mixture screw is sufficient to indicate that the mixture has been readjusted NOTE Due to the close tolerance fit of the throttle val
386. iver Handle J 8092 drive or press replacement bushing into place flush to 010 below oil seal counter bore area Stake bushing using tool J 21465 10 Stake marks to be in bushing lubrication grooves b CA Model Using Tool J 21424 9 with Driver Handle J 8092 drive or press replacement bushing into place flush to 010 below oil seal counter bore area Stake bushing using tool J 21465 10 or J 8400 22 Stake marks to be in bushing lubrication grooves TRUCK SUPP OVERHAUL CASE EXTENSION CL MODEL Fig 15B Inspection 1 Inspect seal case extension to case groove for amage 2 Inspect for cracks or porosity 3 Inspect dowel pin in rear face for damage 4 Inspect oil seal for damage If replacement is required proceed as follows a Pry oil seal from extension b Apply non hardening sealer to outside of new oil seal and install oil seal into case extension using tool 2 24057 5 Inspect ball bearing assemblies If they are damaged or if they require cleaning proceed as follows a Remove rear seal b Remove snap ring e Remove ball bearings and bearing spacer using a brass rod on the outside race of bearing arbor press can be used if tool to press bearing out is located on outer race of bearing CAUTION DO NOT locate against inner race or balls d Install ball bearing assembly and spacer bearing first e Install ball bearing assembly and snap ring f Install new rear oil se
387. k of wood or other suitable object fig 71 and drive roll pin from drive gear Make sure distributor is supported in such a way that no damage will occur to distributor shaft while removing roll pin 3 On 8 cylinder distributors remove drive gear shim and tanged washer from distributor shaft 4 On 6 cylinder distributors remove drive gear from distributor shaft 5 Remove any burrs that may have been caused by removal of roll pin and remove shaft with rotor attached from distributor housing 6 Use needle nose pliers or similar tool to remove pole piece and plate assembly electrical leads from W White and G Green terminals of module Do not remove leads by pulling on the wires as damage to the leads may occur TRUCK SUPP SERVICE Place distributor shaft Remove lock ring from top of pole piece and plate assembly fig 8i and remove pole piece and plate assembly from distributor housing Lubricate felt wick with a few drops of motor oil and install replacement pole piece and plate assembly over upper bushing and vacuum advance unit Make sure the retainer bow that holds the white and green electrical leads together is color coded yellow Install lock ring fig 8i and then connect green electrical lead of pole piece and plate assembly to G terminal of module Then connect white lead of pole piece and plate assembly to W terminal of module with rotor attached in distributor housing On 8
388. l bearings with a lubricant as specified in the Recommended Fluids amp Lubricants chart at the end of this section A 10 MANUAL STEERING GEAR Check for seal leakage around the pitman shaft and housing If leakage is evident solid grease oozing out not just oily film it should be corrected immediately A 11 CLUTCH CROSS SHAFT Lubricate clutch cross shaft lever A 12 AUTOMATIC TRANSMISSION FLUID Under normal driving conditions change the transmission fluid and service the sump filter Gf so equipped every 60 000 miles Under unusual conditions such as constant driving in heavy city traffic trailer pulling and commercial applications services should be performed at 15 000 mile intervals See elsewhere in this manual for further details on transmission care TRUCK SUPP SERVICE I Inam 0 14 GENERAL INFORMATION AND LUBRICATION SECTION B SAFETY MAINTENANCE NOTE Items B 1 a thru w can be checked by the owner while Items B 2 thru B 10 should only be checked by a qualified mechanic It is particularly important that any safety systems which may have been adversely affected in an accident be checked and repaired as necessary before the vehicle is returned to use 1 SAFETY CHECKS TO BE PERFORMED BY OWNER The following checks should be made regularly during operation at no greater interval than 6 months or 7 500 miles whichever occurs first and more often when the need is indicated Any def
389. l messa c i nms o d gunmm M DVvys I 1A 6 HEATER AND AIR CONDITIONING ADD OIL CONDENSOR au ono ce eee Q IR e ure da WI SUM m qu WO AEN Pew OUNCE EVAPORATOR Dad ew OUNGES EE VIR 5 49 uda 54 D me des ous Se Routes s FINO DNCE COMPRESSOR AMOUNT OF OIL DRAINED AMOUNT OF OIL CONDITION FROM COMPRESSOR TO INSTALL REPLACING COMPRESSOR WITH MORE THAN 4 OZ IN A 6 DRAIN NEW COMPRESSOR REFILL A NEW COMPRESSOR 1 2 OZ IN RA WITH NEW OIL SAME AMOUNT AS DRAINED FROM OLD COMPRESSOR LESS THAN 4 OZ IN A 6 DRAIN NEW COMPRESSOR 1 2 OZ IN R 4 INSTALL NEW OIL IN NEW COMPRESSOR 602 IN A 6 302 IN RA REPLACING COMPRESSOR MORE THAN 402 6 SAME AS ABOVE PLUS AN WITH A SERVICE REBUILT 1 2 OZ IN R 4 ADDITIONAL OUNCE MORE OIL COMPRESSOR IS RETAINED IN A DRAINED COMPRESSOR THAN ONE THAT HAS BEEN REBUILT LESS THAN 4 OZ IN A G SAME AS ABOVE PLUS AN 1 2 OZ IN R 4 ADDITIONAL OUNCE UNABLE TO RUN COMPRESSOR MORE THAN 1 1 2 OZ IN A 6 SAME AS ABOVE BEING REPLACED PRIOR TO 1 2 OZ IN A 6 REMOVAL FROM CAR AND SYSTEM APPEARS TO HAVE SAME AS ABOVE LOST LITTLE OR NO OIL LESS THAN 1 1 2 OZ IN A 6 1 202 IN R 4 OR SYSTEM APPEARS TO HAVE LOST MAJOR AMO
390. l and Housing Assembly Pulley Bearing Bearing Retainer Pulley Retainer Ring Clutch Plate and Hub Assembly Retainer Ring Lock Nut Suction lt LL Crossover Cover Spacer D Bearing Front Cylinder Half Needle Bearing 7 p Hn A Dowel Pins E 2 mr i O Ring Bushing Front Suction Reed Front Discharge Valve Plate Assembly HOSS3HdWOO C L SUCTION REED TEFLON PISTON RING BALL SHELL SHAFT AXIAL PLATE v PISTON lt SHOE DISC REAR HEAD gt FN OIL PUMP AIR CONDITIONING COMPRESSOR 1 3 FRONT DISCHARGE VALVE PLATE SHAFT SEAL ASM PULLEY PULLEY BEARING AND HUB ASSEMBLY SEAL SEAT RETAINER RING SUPERHEAT SWITCH PRESSURE RELIEF VALVE OIL PICK UP TUBE BEARING OIL SUMP AER REAR CYLINDER HOLE HALF SEAL SLEEVE ABSORBENT SLEEVE CLUTCH COIL AND HOUSING FRONT CYLINDER SPACER y CAL fe A RETAINER RING convex 25772 SIDE FACING SPACER SHAFT NUT Fig 2 A 6 Compressor Cross Section CAUTION Do not kink or place excessive tension on lines or hoses When a compressor is removed from the car for servicing the amount of oil remaining in the compressor should be drained and measured This oil should then be discarded and new 525 viscosity refrigerant oil added to the compressor CLUTCH PLATE AND HUB ASSEMBLY Remove 1 Place Holding
391. l mixtures TRUCK SUPP SERVICE 6M 20 ENGINE FUEL E G R EXHAUST GAS RECIRCULATION TIMED CANISTER PURGE IDLE RESTRICTION 21 IDLE AIR IDLE PASSAGE IDLE TUBE MAIN METERING JETS EGR VALVE TIMED VACUUM EGR TUBE auus OFF IDL f DISCHARGE PORTS k IDLE NEEDLE DISCHARGE HOLE THROTTLE VALVE Fig 22 Idle Low Speed System MAIN METERING SYSTEM Fig 23 As the throttle valves continue to open the edge of the valves are gradually moving away from the wall of the carburetor bore reducing the vacuum acting on the idle needle and off idle discharge ports which gradually decreases fuel flow from the idle system With the increased throttle opening there is increased air velocity in the venturi system This causes a drop in pressure in the large venturi which is increased many times in the small venturi Since the low pressure high vacuum is now in the small venturi fuel will flow in the following manner Fuel from the float bowl passes through the main metering jets into the main wells and rises in the main well tubes Plastic main well inserts are used in the main wells to provide smooth fuel flow for efficient metering This results in improved fuel control in the off idle transfer and part throttle range of operation Air entering the main wells PULL OVER ENRICHMENT FUEL FEED MAIN WELL AIR BLEED NOZZLE AIR BLEEDS ASPIRATOR BLEED FUEL PICKUP TUBE MAIN NOZZL
392. l should be added as necessary The oil level should be maintained in the safety margin neither going above the FULL line nor below ADD OIL line NOTE The oil gauge rod is also marked Use SE Engine Oil as a reminder to use only SE oils Supplemental Engine Oil Additives The regular use of supplemental additives is specifically not recommended and will increase operating costs However supplemental additives are available that can effectively and economically solve certain specific problems without causing other difficulties For example if higher detergency is required to reduce varnish and sludge deposits resulting from some unusual operational difficulty a thoroughly tested and approved additive G M Super Engine Oil Supplement or equivalent 1s available Drive Belts Drive belts should be checked every 7 500 miles or 6 months for proper tension loose belt will affect water pump and generator operation POSITIVE CRANKCASE VENTILATION P C V VALVE Every 30 000 miles or 24 months the valve should be replaced Connecting hoses fittings and flame arrestor should be cleaned At every oil change the system should be tested for proper function and serviced if necessary Also see maintenance schedule at end of this section TRUCK SUPP SERVICE 0 8 GENERAL INFORMATION AND LUBRICATION AIR INJECTION REACTOR SYSTEM A I R CONTROLLED COMBUSTION SYSTEM C C S The Air Injection Reactor system should
393. l the shaft touches the housing Fig 14 Positioning Case For Best Clearance REAR SUSPENSION PROPSHAFT AND AXLE 4 5 C LOCK THRUST BLOCK r3 3 C LOCK CORRECT INCORRECT SIDE GEAR Fig 15 Correct C Lock Position Reach into the case with a screwdriver or similar tool and rotate the C lock until its open end points directly inward as shown in figure 15 The axle shaft cannot be pushed inward until the C lock is properly positioned Do not force or hammer the axle shaft in an attempt to gain clearance When the C lock is positioned to pass through the end of the thrust block push the axle shaft inward as shown in figure 16 and remove the C lock Remove the axle shaft and repeat steps 5 and 6 for the opposite axle shaft When installing C locks keep the pinion shaft partially withdrawn Place the C lock in the same position shown in figure 15 Carefully withdraw the axle shaft until the C lock is clear of the thrust block When both locks are installed install the pinion shaft and lock screw TRUCK SUPP SERVICE SECTION 5 BRAKES The following caution applies to one or more steps in the assembly procedure of components in this portion of the manual as indicated at appropriate locations by the terminology See Caution on page 1 of this section CAUTION THIS FASTENER IS AN IMPORTANT ATTACHING PART IN THAT IT COULD AFFECT THE PERFORMANCE OF VITAL COMPONENTS AND SYST
394. lace a ball in each socket Use balls previously removed if they are to be re used 7 Lubricate cavity of a ZERO shoe disc with 525 viscosity refrigerant oil and place shoe disc over ball in front end of piston Fig 37 Front end of piston has an identifying notch in casting web Fig 32 CAUTION Exercise care in handling the Piston and Ring Assembly particularly during assembly into and removal from the cylinder bores to prevent damage to the Teflon piston rings Shoe discs should not be installed on rear of piston during following Gaging operation 8 Rotate shaft and axial plate until high point of axial plate is over the No 1 Piston cylinder bore 9 Lift shaft assembly up and hold front thrust race and bearing assembly against axial plate hub AIR CONDITIONING COMPRESSOR 1 15 PISTON DRIVE BALL ONLY FRONT THRUST RACES AND BEARING REAR NEEDLE THRUST BEARING AND ZERO THRUST RACES PISTON DRIVE BALL AND ZERO SHOE DISC AT FRONT FRONT CYLINDER Fig 38 Installing Piston During Gaging Operation 10 Position piston over No 1 cylinder bore notched end of piston being on bottom and piston straddling axial plate and lower the shaft to allow piston to drop into its bore Fig 38 11 Repeat Steps 6 through 10 for Pistons No 2 and No 3 12 Install rear cylinder half on pistons aligning cylinder with discharge cross over tube hole in front cylinder Tap into place using a plastic mallet or piece o
395. lace as necessary TRUCK SUPP SERVICE ENGINE 6 11 NOISY VALVE LIFTERS Check for broken valve springs and replace as necessary Check for worn or sticking rocker arms and repair or replace as necessary Check for worn or bent push rods and replace as necessary Check for valve lifters incorrectly fitted to bore size and correct as necessary Check faulty valve lifter plunger or push rod seat and replace lifters as necessary Check for plungers excessively worn causing fast leakdown under pressure and replace as necessary Check for excessively worn camshaft lobes and replace if necessary Check valve lifter oil feed holes plugged causing internal breakdown and correct as necessary Check faulty valve lifter check ball nicked flat spot or out of round and replace as necessary Check rocker arm retaining nut to be installed upside down and correct as necessary Check for end of push rod excessively worn or flaked and replace as necessary TRUCK SUPP SERVICE SECTION 6K ENGINE COOLING GENERAL With the exception of the following additions and changes refer to Section 6K Engine Cooling and Section 13 Radiator and Grille of the 1974 Light Duty Truck Service Manual for maintenance and checking the engine cooling system MAINTENANCE AND ADJUSTMENTS PRESSURE CHECKING COOLING SYSTEM FOR LEAKS The radiator cap is a pressure relief type This cap is
396. late Spring Plug Detent Plate Spring Plug Gasket Detent Plate Spring Detent Plate Lockout Shifter Shaft 0 Ring Seal Lockout Shaft Connector Link 0 Ring Seal Range Selector Shifter Shaft Range Selector Shift Fork Detent Plate Pivot Pin Thrust Washer Spacer short Range Selector Counter Gear Countergear Roller Bearings and Spacers 72 Bearings Req d Countergear Shaft Thrust Washer Input Shaft Roller Bearings 15 Req d Thrust Washer Pins 2 Req d Input Shaft 0 Ring Seal Low Speed Gear and Bushing Thrust Washer Input Shaft Bearing Retainer Input Shaft Bearing Input Shaft Bearing Retaining Ring Large Input Shaft Bearing Retaining Ring Chain Drive Housing Lockout Shift Rail Poppet Plug Gasket Spring and Ball 1 2 3 4 5 amp 7 8 9 10 2 1 PPS P Q2 Q2 59 CO CO 569 Q GO CO NJ NJ NJ N N ca m gt G S 05 48 49 50 51 52 53 54 55 56 57 58 59 Front Qutput Shaft 51 62 53 64 65 66 67 68 B9 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 80 Washer 82 90 9192 Thrust Washer Lubricating Thrust Washer Retaining Ring
397. lbs Front Cargo amp Rear Cargo amp Pass Load 450 lbs Pass Load 1940 lbs 2711 Ibs 3489 lbs TOTAL WEIGHT AT GROUND 6200 lbs Curb weight equals the weight of the vehicle without driver passenger or cargo but including fuel and coolant Fig 4 Typical Vehicle Loaded Condition TRUCK SUPP SERVICE 0 6 GENERAL INFORMATION AND LUBRICATION 0 a dG sns i n s W M n X LUBRICATION INDEX Maintenance 2 0 6 Propeller Shaft Slip 0 9 Engine ccc ec ai 0 6 Universal Joints cse inrer e tenens 0 9 Oil and Filter Recommendations 0 6 Wheel Bearings Drive Belts asa aaah aaa aras 0 7 dugaan eh tal a up 0 9 Positive Crankcase Ventilation P C V 0 7 0 9 Air Injection Reactor System A L 0 8 Brake Master Cylinder 2 2 9 0 10 Controlled Combustion System C C S 0 8 Brake and Clutch Pedal Springs 0 10 Evaporation Control System E C S 0 8 Parking 0 10 Early Fuel Evaporation E F E System 0 8 Steering Ait ukna ee i tue 0 8 Manual Steering Gear esee 0 10 Fuel 0 8 Steering L
398. lbs Rear Output Shaft Housing Bolts 30 ft Ibs Rear Output Shaft Yoke Lock Nut 150 ft Ibs P T O Cover Bolts 15 ft Ibs Front Output Shaft Rear Bearing Retainer Bolts 30 ft Ibs Drain and Filler Plugs 30 ft lbs Transfer Case to Frame Bolts 130 ft Ibs Transfer Case to Adapter Bolts 25 ft Ibs Adapter Mount Bolts 25 ft lbs Transfer Case Bracket to Frame Nuts Upper 30 ft ibs Transfer Case Bracket to Frame Nuts Lower 65 ft lbs Adapter to Transmission Bolts Manual 22 ft 165 Adapter to Transmission Bolts Automatic 35 ft Ibs Transfer Case Control Mounting Bolt 100 ft Ibs TRUCK SUPP SPECS SPECIFICATIONS 21 AUTOMATIC TRANSMISSIONS SECTION 7A NEW PROCESS TRANSFER CASE MODEL 203 Adapter to Transfer Case Attaching Bolts 38 ft Adapter to Transmission Attaching Bolts 40 ft Transfer Case Bracket to Frame nuts upper 50 ft Transfer Case Bracket to Frame nuts lower 65 ft Transfer Case Shift Lever Attaching Nuts 25 ft Transfer Case Shift Lever Rod Swivel Lock Nuts Transfer Case Shift Lever Locking Arm Nut 150 in Skid Plate Attaching Bolt Retaining Nuts 45 ft Crossmember Support Attaching Bolt Retaining Nut Adapter Mount Bolts Intermediate Case to Range Box Bolts
399. ld vacuum drops below a pre determined level the control valve closes the throttle actuator retracts and throttle lever closes to idle position SERVICE PROCEDURE CONTROL VALVE Fig 9 Check Diagnosis and Adjustment 1 Disconnect valve to carburetor hose at carburetor and connect to an external vacuum source equipped with a vacuum gauge 2 Disconnect control valve to actuator hose at actuator and connect to a vacuum gauge 3 Place finger firmly over end of bleed fitting the foam air filter need not be removed 4 Apply a minimum of 23 in Hg vacuum to control valve and seal off vacuum source The gauge on actuator side should read the same as source gauge It not then control valve needs adjustment If vacuum drops off on either gauge finger still on bleed fitting valve is leaking and must be replaced TRUCK SUPP SERVICE 6 8 EMISSION CONTROL SYSTEMS FROM CARBURETOR VACUUM VACUUM SWTICH ADJUSTING SCREW VENT FILTER TO THROTTLE LEVER ACTUATOR DIAPHRAGM TIGHTEN TO 150 IN LBS THROTTLE ACTUATOR TIGHTEN TO 20 FT LBS Fig 9 Throttle Return Control Valve 5 With a minimum 23 in Hg vacuum level in control valve remove finger from bleed fitting The vacuum reading on actuator side will drop to zero and reading on source gauge will drop to a value which is the va ve set point The valve set point for a 350 400 V8 is 21 5 in Hg and for a 454 V8 is 21 0 in Hg
400. le intermediate choke shaft from choke housing remove coil lever retaining screw at end of shaft inside the choke housing Fig 15MQ Then remove thermostatic coil lever from flats intermediate choke shaft Remove intermediate choke shaft from the choke housing by sliding outward The fast idle cam can now be removed from the intermediate choke shaft Fig 16MQ CAUTION Remove the cup seal from inside choke housing shaft hole if the housing 15 to be immersed carburetor cleaner Also remove the cup seal from the float bowl plastic insert for bowl cleaning purposes DO NOT ATTEMPT TO REMOVE PLASTIC INSERT CHOKE ATTACHING HOUSING Fig 15MQ Removing Choke Housing TRUCK SUPP OVERHAUL 6M 16 CARBURETOR PLASTIC TUBE SEAL REAR VACUUM BREAK LEVER LOCKOUT PIN SECONDARY FAST IDLE LOCK OUT CAM FOLLOWER LEVER INTERMEDIATE CHOKE SHAFT Fig 16MQ Choke Housing Assembly Float Bowl Disassembly 1 Remove fuel inlet nut gasket and filter Fig 17MQ 2 Remove secondary air baffle if replacement is required 3 Remove pump well fill slot baffle if replacement is required 4 Remove throttle body by removing throttle body to bowl attaching screws Fig 18MQ 5 Remove throttle body to bowl insulator gasket Fig 19MQ Throttle Body Disassembly 1 Remove pump rod from throttle lever 2 DO NOT REMOVE idle mixture limiter caps unless it is necessary to replace the mixture needles or normal soaking
401. le is a solid state unit containing five complete circuits which control spark triggering switching current limiting dwell control and distributor pick up Dwell angle is controlled by a transistor circuit within the module and is varied in direct relation to engine speed Pick Up Assembly The pick up assembly consists of the following 1 A rotating timer core with external teeth which is turned by the distributor shaft TAUCK SUPP SERVICE 2 A stationary pole piece with internal teeth 3 A pick up coil and magnet which are located between the pole piece and a bottom plate Centrifugal and Vacuum Advance The centrifugal and vacuum advance mechanisms are ENGINE ELECTRICAL 6Y 11 basically the same types of units that provide spark advance in the breaker type system Centrifugal advance is achieved through the rotation of the timer core in relation to the distributor shaft Vacuum advance is achieved by attaching the pick up coil and pole piece to the vacuum advance unit actuating arm THEORY OF OPERATION The pick up coil is connected to transistors in the electronic module The electronic module is connected to the primary windings in the coil As the distributor shaft turns the timer core teeth out of alignment with the teeth of the pole piece a voltage is created in the magnetic field of the pick up coil The pick up coil sends this voltage signal to the electronic 0000000000000000 HIGH ENERGY IGNITION SCH
402. lenoid has been removed This terminal was removed because with the High Energy Ignition System there is no longer any requirement for the electrical lead from the starter solenoid to the ignition coil Refer to Section 6Y of the 1974 Truck Service Manual for all service procedures HIGH ENERGY IGNITION SYSTEM INDEX General 4012222 2 6Y 10 Theory of Operation nno 6Y 11 Service Operations u 6Y 12 Routine Maintenance 4 40000 6Y 12 Electronic Module 6Y 12 Spark Plug 6Y 12 Timing Light Connections eese 6Y 12 Tachometer Connections 6Y 12 Other Test Equipment u eee 6Y 12 Centrifugal Vacuum Advance 6Y 12 DiStFIDULOE iiid I ace ies 6Y 12 Removal asa nn a eU 6Y 12 Installation one 6Y 13 2 6Y 13 Assembly redi aue manie 6Y 13 Ignition Coil 8 Cylinder 6Y 15 Remova oet ate a Q u tas 6Y 15 Installation one rennen reete 6Y 15 Ignition Coil 6 Cylinder 6Y 15 Removal e eere eet tum e eitis 6Y 15 Installations iiss eee cmi dg ES 6Y 15 Dia gnosis S155 EUER 6Y 17 TRUCK SUPP SERVICE 6Y 10 ENGINE ELECTRICAL DEM RD ris C E i i X GENERAL DESCRIPTION
403. line at the gasoline tank prior to blowing air can damage the tank strainer If the line is restricted replace or clean it If the line was not restricted proceed to other areas such as gas tank or car buretor The fuel pump is not at fault TRUCK SUPP SERVICE ENGINE FUEL 6M 75 SPECIAL TOOLS J 22973 THER MAC THERMOMETOR J 8328 CARBURETOR HOLDING TOOL J 9789 01 UNIVERSAL CARBURETOR Set of 4 GAUGE SET 1 25322 PUMP LEVER PIN DRIVE PUNCH t a J 23417 CHOKE LEVER J 5197 BENDING TOOL INSTALLING TOOL Fig 1ST Special Tools TRUCK SUPP SERVICE SECTION 6T EMISSION CONTROL SYSTEM CONTENTS OF THIS SECTION General i steer Air Injection Reactor System Emission Hose Routings Early Fuel Evaporation System Throttle Return Control System GENERAL LIGHT DUTY EMISSIONS The following emission control systems are used on a light duty truck with light duty emissions Positive Crankcase Ventilation PCV All Vehicles Withdraws oil vapor and gas vapor from the various cavities throughout the engine for burning in all combustion cycle Refer to 1974 Light Duty Truck Service Manual for service procedures Exhaust Gas Recirculation EGR All Vehicles Meters exhaust gas into induction system for recirculation through the combustion cycle to reduce oxides of nitrogen emissions Refer to 1974 Light Duty Truck Service Manual for service procedures Evaporation
404. ll The pump plunger is connected by linkage directly to a lever on the throttle shaft When the pump plunger moves upward in the pump well as happens during throttle closing fuel from the float bowl enters the pump well through a slot in the side of the pump well and flows past the synthetic pump cup seal into the bottom of the pump well The pump cup is a floating type the cup moves up and down on the pump plunger head When the pump plunger is moved upward the flat on the top of the cup unseats from the flat on the plunger head and allows free movement of fuel through the inside of the cup into the bottom of the pump well This also vents any vapors T DISCHARGE SPRING RETAINER PUMP LEVER PUMP PLUNGER amp DURATION PUMP DISCHARGE SPRING SPRING amp BALL PUMP FILL SLOT CUP SEAL PUMP RETURN SPRING PUMP CUP OPERATION Fig 6 Accelerating Pump System TRUCK SUPP SERVICE 6M 6 ENGINE FUEL which may be in the bottom of the well so that a solid charge of fuel can be maintained in the fuel well beneath the plunger head When the throttle valve is opened as happens during acceleration the connecting pump linkage forces the pump plunger downward The pump cup seats instantly and fuel is forced through the pump discharge passage where it unseats the pump discharge check ball and passes on through the passage to the pump jet located at the top of the float bowl where it sprays into the
405. loat bowl Fill bowl with fuel and look for leaks TRUCK SUPP SERVICE 6M 18 ENGINE FUEL 2GC CARBURETOR General Description onn 6M 18 Theory of Operation sse 6M 19 Float System eerie irte 6M 19 Idle System tue Genere dents 6M 19 Main Metering System sess 6M 20 Power Enrichment System 6M 20 Pump 6M 21 Maintenance and 6M 22 Idle Speed Adjustment esee 6M 22 Idle Mixture t Ori Do qiie 6M 22 Idle Mixture Adjustment 2 2042 22 6M 22 Pump Rod Adjustment sss 6M 22 Intermediate Choke Rod Adjustment 6M 22 Automatic Choke Coil Adjustment 6M 23 Fast Idle Cam Adjustment sse 6M 23 Vacuum Break Adjustment sees 6M 23 Choke Unloader Adjustment 6M 24 Service Operations tete 6M 24 Carburetor Replacement 6M 24 Fuel Filter Replacement 6M 25 Air Horn Tightening 6M 25 Diagnosis nte ere Per CERES CETT ER 6M 26 GENERAL DESCRIPTION The Model 2GC Figs 19 and 20 is equipped with an integral choke attached to the throttle body assembly A large drilled hole in the air horn leads from inside the air horn bore to a vapor dome loc
406. loat to specifications by bending the float arm at point shown Fig 10C TRUCK SUPP OVERHAUL 6M 10 CARBURETOR 3 visuALLY CHECK FOR FLOAT ALIGNMENT 1 MEASURE FROM LIP AT TOE OF FLOAT TO AIR HORN GASKET 2 BEND HERE TO ADJUST Fig 10C Float Level Adjustment Float Drop Adjustment With air horn right side up so that float can hang free measure distance from lip at toe of float air horn gasket Adjust float drop to specifications by bending tang Fig 11C at the rear of the float hanger 10 Install choke rod in upper choke lever and collar assembly rotating rod until squirt in end of rod aligns with slot in lever Air Horn to Float Bowl 1 Place the air horn assembly on bowl making certain that the accelerator pump plunger is correctly positioned into pump well and will move freely 2 Install lockwashers and tighten eight air horn attaching screws evenly and securely Fig 12C Y AIR HORN HELD RIGHT SIDE UP TO ALLOW FLOAT TO HANG FREE MEASURE SPECIFIED DISTANCE FROM GASKET SURFACE TO AT OF FLOAT BEND FLOAT TANG ADJUST FOR PROPER SETTING 4 NEEDLE MUST NOT WEOGE AT MAXIMUM DROP Fig 11C Float Drop Adjustment Fig 12C Air Horn Tightening Sequence 3 Install filter pressure relief spring into air horn casting then install fuel inlet filter gasket end facing nut and fuel inlet nut and gasket Tighten nut to 25 ft Ibs 4 Install fast idle cam to low
407. lting from the type of driving conditions under which your vehicle is used is the main consideration in establishing the proper frequency of transmission fluid changes Change the transmission fluid and filter every 15 000 miles if the vehicle is usually driven under one or more of the following conditions which considered severe transmission service e In heavy city traffic e Where the outside temperature regularly reaches 90 F e In very hilly or mountainous areas e Frequent trailer pulling e Commercial uses such as taxi police car or delivery service If you do not use your vehicle under any of these conditions change the fluid and filter every 60 000 miles To Change Turbo Hydra Matic 400 and Turbo Hydra Matic 350 fluid remove fluid from the transmission sump add approximately 7 5 pints U S measure 6 25 pints Imperial measure for the Turbo Hydra Matic 400 and 2 1 2 qts U S measure 2 qts Imperial measure for the Turbo Hydra Matic 350 of fresh fluid to return level to proper mark on the dipstick Every 60 000 Miles the Turbo Hydra Matic 400 transmission sump filter should be replaced 3 AND 4 SPEED MANUAL TRANMISSION LUBRICANT Every 6 months or 7 500 miles whichever occurs first check lubricant level and add lubricant if necessary to fill to level of filler plug hole with SAE 80W or SAE 80W 90 GL 5 Gear Lubricant If temperatures below 32 F are expected use SAE 80W GL 5 Gear Lubricant only Fo
408. lts Rear Mount to Crossmember Bolt Crossmember Mounting Bolts Oil Cooler Line Line Pressure Take Off Plug Strainer Retainer Bolt Oil Cooler Pipe Connectors to Transmission Ibs lbs lbs lbs 16 Ibs in lbs lbs lbs lbs lbs Ibs 5 165 lbs Bottom Pan Attaching Screws 12 ft lbs Ibs Ibs 5 lbs lbs lbs lbs 5 lbs lbs lbs lbs lbs lbs lbs in Ibs TRUCK SUPP SPECS SPECIFICATIONS 22 STEERING SECTION 9 STEERING GEAR RATIOS Vehicle Gear Overall Gear Overall Ratio Ratio Ratio Ratio G10 20 P20 30 C20 30 24 6 1 16 1 13 2 1 K10 20 24 1 to to to 13 1 17 2 1 17 5 1 MANUAL STEERING GEAR C10 30 G10 30 P10 K10 20 P20 30 Components Thrust Bearing 6 to 11 4to6 9to12 Preload Ibs in Ibs in lbs in Adjuster Plug Lock Nut Over Center Preload 85 Ibs ft 5 11 lbs in 4 to 10 Ibs in 9 to 13 Ibs in Over Center Lock Nut 25 lbs ft Total Steering 18 5 in 14 Ibs in 25 lbs in Gear Preload Max Max Max In excess of thrust bearing preload POWER STEERING GEAR Components All C P K and G 1 2 to 2 lbs in 80 Ibs ft Steering Gear Ball Drag Thrust Bearing Preload Adjuster Plug Locknut Over Center Preload
409. lve where it exists into the throttle body bore Normally the compensator valve is held closed by tension of the bi metal strip and engine vacuum During extreme hot engine operation excessive fuel vapors in the carburetor can enter the engine manifold causing richer than normally required mixtures This can result in rough engine idle and stalling At a pre determined temperature when extra air is needed to offset the enrichening effects of fuel vapors the bi metal strip bends and unseats the compensator valve uncovering the air channel leading from the compensator valve chamber to the throttle body bore This allows enough air to be drawn into the engine manifold to offset the richer mixtures and maintain a smooth engine idle When the engine cools and the extra air is not needed the bi metal strip closes the valve and operation returns to normal The compensator valve assembly is held in place by the dust cover over the valve chamber A seal is used between the compensator valve and float bowl casting In order to insure proper idle adjustment when the engine is hot the compensator valve must be closed To check this plug the compensator inlet hole inside the air horn bore pencil can be used If no drop in engine rpm is noted on a tachometer the valve is closed if the valve is open leave plug in hole when adjusting idle or cool engine down to a point where the valve automatically closes for proper idle adjustment CAUTION A w
410. ly Align the step projections of shell installing fixture J 25008 2 to contact compressor shell evenly both sides 6 Push compressor shell as close to O ring Fig 95 as possible by hand and check for equal alignment of shell around cylinder Tighten fixture screws finger tight 7 Using a wrench alternately tighten each approximately 1 4 turn to push compressor shell over O rings and back against shell stop flange at the rear of compressor cylinder If one screw appears to require more force to turn than the other immediately turn the other screw to bring the screw threading sequence in step or the shell will be cocked and made more difficult to install Normal installation does not require much force on wrench if Screws are kept in step while turning 8 When shell is seated against the stops bend shell retaining strap down into place by tapping gently with AIR CONDITIONING COMPRESSOR 1 37 a hammer 9 Remove shell installing fixture J 25008 2 and leak test compressor OIL CHARGE The radial four cylinder compressor is charged with 6 0 ounces of 525 viscosity oil During normal operation a certain amount of oil will circulate with the Refrigerant 12 R 12 in the system When necessary to replace a system component it is recommended that oil be added to the system in accordance to the following procedure If compressor is operable idle vehicle for 10 minutes with the A C controls set for Maximum Cooling
411. ly on manifold 5 Install bolt and tighten securely 6 Adjust and connect choke rod as outlined 7 Start and warm up engine then check operation of choke and install air cleaner AIR HORN TIGHTENING SEQUENCE Refer to Figure 18 for proper air horn tightening sequence Fig 18 Air Horn Tightening Sequence TRUCK SUPP SERVICE ENGINE FUEL 6M 13 DIAGNOSIS GENERAL When carburetor troubles are encountered they can usually be diagnosed and corrected with an adjustment as outlined below and under Maintenance and Adjustments Before diagnosing the carburetor as the trouble area check and diagnose the following 1 Fuel Supply 2 Fuel pump pressure and volume 3 Plugged fuel filter or fuel lines 4 Linkage and emission control systems 5 Engine compression 6 Ignition system firing voltage 7 lgnition spark timing 8 Spark plugs 9 Secure intake manifold 10 Engine temperature Use the following tables to diagnose carburetor Problem Idle speed setting Manifold vacuum hoses disconnected or improperly in stalled Carburetor loose on intake manifold Intake manifold is loose or gaskets are defective Hot idle compensator not operating where used Carburetor flooding NOTE Also check carburetor flooding when engine cranks turn over but will not start or starts hard when cold ENGINE IDLES ROUGH AND STALLS Re set low and curb idle speeds under maintenance and adjustments
412. m plunger Install front vacuum break control and bracket assembly to air horn using two retaining screws through the bracket Tighten screws securely NOTE Do not attach vacuum break hose until vacuum break adjustment is completed Refer to Service Section for adjustment procedure Connect upper end of pump rod to pump lever by placing rod in specified hole in lever Align hole in pump lever with hole in air horn casting using J 25322 Using small screwdriver push pump lever roll pin back TRUCK SUPP OVERHAUL CARBURETOR 6 19 GAUGE FROM TOP OF CASTING TO TOP OF FLOAT GAUGING POINT 3 16 BACK FROM END OF FLOAT AT TOE SEE INSET INSET 1 HOLD RETAINER NS FIRMLY IN PLACE d PUSH FLOAT DOWN LIGHTLY AGAINST NEEDLE GAUGING POINT 3 16 BACK FROM J 4 REMOVE FLOAT AND BEND FLOAT ARM UP OR DOWN TO ADJUST 5 VISUALLY CHECK FLOAT ALIGNMENT AFTER ADJUSTING Fig 22MQ Float Level Adjustment through casting until end of pin is flush with casting bosses in air horn CAUTION Use care installing the small roll pin to prevent damage to pump lever casting bosses 5 Install two secondary metering rods into the secondary metering rod hanger upper end of rods point toward each other Install secondary metering rod holder with rods onto air valve cam follower Install retaining screw end tighten securely Work air valves up and down several times to make sure they are free in all po
413. mbly can be removed if desired during choke valve removal Fig 1 2 Remove fast idle cam from boss on float bowl by removing attaching screw Then remove fast idle cam from choke rod and choke rod from upper choke lever Fig 2 Note position of rod and cam for ease in reassembly NOTE Upper choke lever is spun on end of choke shaft and cannot be removed 3 Remove six air horn to bowl attaching screws and lockwashers three long and three short screws TRUCK SUPP OVERHAUL 6M 2 CARBURETOR PRESSURE RELIEF VALVE DISC PRIMARY VACUUM BREAK DIAPHRAGM CHOKE LEVER AUXILIARY VACUUM BREAK DIAPHRAGM Fig 1 Air Horn Assembly 4 Remove primary vacuum break diaphragm unit from the air horn casting Then remove the vacuum break hose assembly and link from slotted diaphragm plunger stem 5 Remove air horn by lifting straight up invert and place on clean bench Air horn to float bowl gasket can remain on bowl for removal later CHOICE SHAFT AND LEVER ASSEMBLY PRIMARY CHOKE VACUUM BREAK AUXILIARY CHOKE DIAPHRAGM VACUUM BREAK DIAPHRAGM IDLE STOP SOLENOID THROTTLE Z LEVER FAST IDLE CAM Fig 2 1MV Carburetor Disassembly 1 If desired the choke valve and choke shaft can be removed from horn by first removing the thermostatic coil lever from the end of choke shaft by removing attaching screw Remove the two choke valve attaching screws then remove the choke valve an
414. ming air pressure beneath the air cleaner with air pressure acting on fuel in the float bowl thereby maintaing a balanced air fuel mixture ratio during part throttle and power operation The internal vent tubes allow the escape of fuel vapors in the float chamber during hot engine operation This prevents fuel vaporization from causing excessive pressure buildup in the float bowl which could result in excessive fuel spillage into the manifold A CLIP j geo NEEDLE INTERNAL VENTS FLOAT NEEDLE A T SEAT Jv J GASKET FLOAT HINGE FLOAT ASSEMBLY FLOAT BOWL FUEL INLET FITTING AND FILTER Fig 2Q0 Float System IDLE SYSTEM FIG 3Q The idle system is on the primary side fuel inlet side of the carburetor to supply the correct air fuel mixture ratios during idle and off idle operation The idle system is used during this period because air flow through the carburetor venturi is not great enough to obtain efficient metering from the main discharge nozzles Each primary bore has a separate and independent idle system consisting of an idle tube idle passages idle air bleeds idle channel restrictions an idle mixture adjustment needle and an idle discharge hole and idle air passage Fuel is forced from the float bowl down through the primary main metering jets into the main fuel wells It passes from the main fuel well up through the calibrated idle tubes which TRUCK SUPP SERVICE 6 56 EN
415. mission in cradle or portable jack install the converter assembly into the pump assembly making certain that the converter hub drive slots are fully engaged with the pump drive gear tangs and the converter installed fully towards the rear of the transmission NOTE The converter used in the CL CM CT and CZ models has six 6 mounting lugs TRUCK SUPP OVERHAUL SECTION 9 STEERING INDEX Overhaul Operations Power Steering Pump Power Steering Gear Special Tools OVERHAUL OPERATIONS Fig 1 Power Steering Pump Pulley Removal All service overhaul procedures for 1976 Light Duty Truck identical to the procedures outlined in the 1974 Overhaul Manual Section 9 with the exception of the following procedures POWER STEERING PUMP Disassembly 1 Remove pump pulley by using tool J 25034 as shown in Figure 1 NOTE Steps 2 15 are identical to the 1974 Overhaul Manual Section 9 Page 9 8 Assembly NOTE Steps 1 19 are identical to the 1974 Overhaul Manual Section 9 Pages 9 11 and 9 12 1 25033 Fig 2 Steering Pump Pulley Installation 20 Install pump pulley by inserting tool J 25033 through pulley hub and threading the bolt into the power steering pulley shaft as shown in Figure 2 NOTE Pulley must be flush with end of shaft CAUTION DO NOT hammer on pump shaft Use special tools to prevent possible damag
416. move snap ring in front of 3rd 4th synchronizer assembly Remove reverse driven gear Press behind second speed gear to remove 3rd 4th synchronizer assembly 3rd speed gear and 2nd speed gear along with 3rd speed gear bushing and thrust washer fig 4X Remove 2nd speed synchronizer ring Supporting 2nd speed synchronizer hub at front face press mainshaft through removing Ist speed gear bushing and 2nd speed synchronizer hub Split 2nd speed gear bushing with chisel and remove bushing from shaft CAUTION Exercise care not to damage mainshaft Fig 2X Shifter Shaft Installation TRUCK SUPP OVERHAUL 1st Speed Gear Reverse Driven Gear 1st Gear Bushing 1st 2nd Gear Synchronizer Hub Assembly 7M 14 MANUAL TRANSMISSION 2nd Speed Blocker Ring 2nd Speed Gear Thrust Washer 3rd Speed Bushing 3rd Speed Gear 3rd Speed Blocker Ring 3rd 4th Speed Synchronizer Hub Assembly 3rd 4th Speed Synchronizer Sleeve Fig 3X Mainshaft Assembly Exploded View 4th Speed Blocker Ring Snap Ring Mainshaft 2nd Speed Gear Bushing TRUCK SUPP OVERHAUL MANUAL TRANSMISSION 7M 15 3RD amp 4TH SYNCHRONIZER Fig 4AX Disassembly of Mainshaft NEW PROCESS TRANSFER CASE MODEL 203 INDEX Disassembly of transfer case a Rear Output Shaft Housing Rear Assembly Rear Output Shaft Housing Front Assembly
417. mp well during severe vehicle maneuvers The pump plunger is spring loaded the upper duration spring is balanced with the bottom pump return spring so that a smooth sustained charge of fuel is delivered during acceleration The pump discharge check ball seats in the pump discharge passage during upward motion of the pump plunger so that air will not be drawn into the passage otherwise a momentary lag in acceleration could result During high speed operation a vacuum exists at the pump jets cavity just beyond the pump jets is vented to the top of the air horn outside the carburetor bores This acts as a suction breaker so that when the pump is not in operation fuel will not be pulled out of the pump jets into the venturi area This insures a full pump stream when needed and prevents any fuel pull over from the pump discharge passage CHOKE SYSTEM Fig 43 and 43A All models have an integral choke housing and thermostatic coil assembly mounted on the carburetor float bowl The M4MC model Fig 43 uses manifold heated hot air for choking and a single front vacuum break unit The M4ME model Fig 43A uses a electric heated choke coil assembly with dual front and rear vacuum break system The choke system operates as follows The thermostatic coil in the choke housing is calibrated to hold the choke valve closed when the engine is cold To close the choke valve depress the accelerator pedal completely to allow the
418. n and correct as necessary k Check for vacuum leaks and repair or replace as necessary Check engine operating temperature and correct as necessary m Check for excessive combustion chamber deposits and correct as necessary n Check for leaking sticking or broken valves and repair or replace as necessary TRUCK SUPP SERVICE 6 8 ENGINE O EXTERNAL OIL LEAKAGE a Check for improperly seated or fuel pump gasket Replace as necessary b Check for improperly seated or broken push rod cover gasket Replace as necessary c Check for improperly seated or broken oil filter gasket Replace as necessary d Check for broken or improperly seated oil pan gasket Replace as necessary e Inspect gasket surface of oil pan to be bent or distorted Repair or replace as necessary f Check for improperly seated or broken timing chain cover gasket Replace as necessary g Inspect timing cover oil seal Replace if necessary h Check for worn or improperly seated rear main bearing oil seal Replace if necessary me Inspect for loose oil line plugs Repair or replace if necessary j Check for engine oil pan drain plug improperly seated Correct as necessary k Inspect camshaft rear bearing drain hole for obstructions Correct as necessary Check for loose rocker arm cover broken or cover distorted or bent Correct as necessary m Check EFE valve switch for leakage Replace if neces
419. n hole in lever facing inward Install new cup seal into inside choke housing shaft hole Lips on seal face inward towards inside of housing Install fast idle cam onto the intermediate choke shaft steps on fast idle cam face downward Fig 16MQ Carefully install fast idle cam and intermediate choke shaft assembly through seal in choke housing then install thermostatic coil lever onto flats on intermediate choke shaft Inside thermostatic choke coil lever is CARBURETOR 6M 17 properly aligned when both inside and outside levers face towards fuel inlet Install inside lever retaining screw into end of intermediate choke shaft Tighten securely Using Tool J 23417 install lower choke rod lever into cavity in float bowl Install plastic tube seal into cavity on choke housing before assembling choke housing to bowl Install choke housing to bowl sliding intermediate choke shaft into lower choke lever Fig 20 NOTE The intermediate choke shaft lever and fast idle cam are in correct relation when the tang on lever is beneath the fast idle cam Do not install choke cover and coil assembly until inside coil lever is adjusted Refer to Service Section for adjustment procedures Float Bowl Model With Hear Vacuum Break 1 Holding down on fast idle cam hot idle position install end of vacuum break rod in hole in intermediate choke lever Install end of vacuum break rod in slot in rear vacuum br
420. n stud not to exceed 60 ft Ibs maximum Plus additional torque required to align castellation with cotter pin hole stud not to exceed 100 ft Ibs maximum TRUCK SUPP SPECS WHEELS AND TIRES SECTION 10 WHEELS Wheel Nut Torque 10 30 Series SERIES DESCRIPTION TORQUE SERIES DESCRIPTION K10 15 7 16 Bolts 6 70 90 Ft Lbs G10 15 7 16 Bolts 6 C P10 515 1 2 Bolts 5 75 100 Ft Lbs G20 25 1 2 Bolts 5 C P20 25 30 35 T Single Wheels 9 16 Bolts 8 90 120 Ft Lbs 030 35 9 16 Bolts 8 110 140 Ft Lbs Single Wheels C P20 25 30 35 Heavy Duty Wheels G30 35 9 16 Bolts 8 5 8 Bolts 10 130 180 Ft Lbs Dual Wheels TIRES See Minimum Tire Inflation and Tire Load and inflation Pressure Charts in Section 10 of this Manual SHEET METAL SECTION 11 TORQUE SPECIFICATIONS ock Support to Hood Hood Lock Catch Hood Stop Bolt Hood Support Rod Assembly Lock Support to Rad Support Rad Support to Frame Radiator Support Bracket to Fender Radiator Support to Fender Rad Grille Panel Tie Bar Assembly Radiator Support Cover Plate Fender Skirt to Fender Fender to Cowl Fender Skirt to Underbody Fender Skirt Rear Supportto Frame Rear Fender to Side Panel Rear Fender Brace to Fender 50 in Ibs Wheel Fender to Side Panel Running board Hangers and Braces
421. n that an adequate stock of service parts is available All parts required for servicing are protected by a preservation process and packaged in a manner which will eliminate the necessity of cleaning washing or flushing of the parts The parts can be used in the mechanism assembly just as they are removed from the service package Piston shoe discs and shaft thrust races will be identified by number on the parts themselves for reference to determine their size and dimension see Fig 41 SHAFT SEAL Seal Leak Detection A SHAFT SEAL SHOULD NOT BE CHANGED BECAUSE OF AN OIL LINE ON THE HOOD INSULATOR The seal is designed to seep some oil for lubrication purposes Only change a shaft seal when a leak is detected by the following procedure When refrigerant system components other than the compressor are replaced the compressor must be removed and oil drained from the compressor if oil was sprayed in large amounts due to leaks or a broken shaft seal Compressor shaft seals unless replaced during a compressor overhaul are to be replaced only on the basis of actual refrigerant leakage as determined by test with electronic type leak detector TRUCK SUPP OVERHAUL SNAP RING PLIERS 21 J 5403 4 EJ Fig 18 Removing or Installing Shaft Seal Seat Retaining Ring WHEN REPLACING THE SHAFT SEAL ASSEMBLY even if the compressor remains on the vehicle during the operation IT WILL BE NECESSARY TO PURGE THE S
422. n the latest product information avail able at the time of publication approval The right is reserved to make changes at any time without notice SERVICE SECTION The Service Section of this manual includes new or revised procedures for maintenance and adjustments minor service op erations and replacement of components CHEVROLET MOTOR DIVISION General Motors Corporation DETROIT MICHIGAN SECTION INDEX GENERAL INFORMATION AND LUBRICATION HEATER AND AIR CONDITIONING BODY FRAME FRONT SUSPENSION REAR SUSPENSION AND DRIVELINE BRAKES EMISSION CONTROL SYSTEMS ENGINE ELECTRICAL CLUTCH AND MANUAL TRANSMISSION AUTOMATIC TRANSMISSION FUEL TANK AND EXHAUST SYSTEM STEERING WHEELS AND TIRES CHASSIS SHEET METAL ELECTRICAL BODY AND CHASSIS RADIATOR See Section 6K GRILLE See Section 11 BUMPERS SPECIFICATIONS AT REAR OF MANUAL cem Printed in U S A SECTION 0 GENERAL INFORMATION AND LUBRICATION CONTENTS OF THIS SECTION General Information eere t ede eere ta 0 1 E bricatiot hee eee outre 0 6 GENERAL INFORMATION INDEX Truck Model Identification sss 0 1 Service Parts Identification 0 3 Vehicle Identification Number and Rating Plate 0 1 Keys and Backs s onte ree es 0 3 Engine unie eee teeth 0 1 Emergency Starting cob eee rv 0 3 Unit and Serial Number Locations
423. nce SECONDARY CLOSING ADJUSTMENT Fig 55 1 Pre set carburetor speed screw to specifications 2 Hold choke valve wide open with cam follower lever off steps of fast idle cam 3 Using specified gauge measure clearance between slot in secondary throttle valve pick up lever and secondary actuating rod 4 Bend secondary closing tang on primary throttle lever as shown to adjust CHOKE VALVE WIDE OPEN FOLLOWER OFF STEPS OF FAST IDLE CAM AGAINST d aes ENGINE IOLE SET TO PROPER L 1 SPECIFIED BEND In CLEARANCE TO ADJUST Fig 55 Secondary Closing Adjustment ENGINE FUEL 6M 45 1 OPEN PRIMARY THROTTLE IU UNTIL ACTUATING LINK id L n CONTACTS TANG BEND TANG 2 LINX SHOULD BE IN CENTER Of SLOT Fig 56 Secondary Opening Adjustment SECONDARY OPENING ADJUSTMENT Fig 56 1 Lightly open primary throttle lever until link just contacts tang on secondary lever 2 With link against tang the link should be in center of slot in the secondary lever 3 Bend tang on secondary lever as shown if necessary to adjust AIR VALVE SPRING WIND UP ADJUSTMENT Fig 57 NOTE This adjustment should be made only when replacing air valve or a change in specifications 1 Remove front vacuum break diaphragm unit and air valve dashpot rod 2 Loosen lock screw using special hex wrench 3 Turn tension adjusting screw counterclockwise until air valve opens part
424. ncorrectly assembled parts of the exhaust system are frequently the cause of annoying noises and rattles due to improper clearances or obstructions to the normal flow of gases Leave all clamp bolts and muffler bolts loose until all parts are properly aligned and then tighten working from front to rear Exhaust system hangers hanger brackets and clamps which are damaged should be replaced to maintain proper exhaust system alignment NOTE When reinstalling exhaust pipe to manifold always use new packings and nuts Be sure to clean manifold stud threads with a wire brush when installing the new nuts CONVERTER HEAT SHIELD C 10 Model Refer to Figure 2 for converter heat shield CATALYTIC CONVERTER FIGS 3 and 4 C10 and G10 Model Removal 1 Raise vehicle on hoist TRUCK SUPP SERVICE Fig 2 Heat Shield C10 Model Remove clamps at front and rear of converter Cut converter pipes at front and rear of converter and remove converter On CIO models remove converter to transmission support attaching Remove converter pipe to front exhaust pipe and converter pipe to rear exhaust pipe Installation 1 4 5 With sealer on exhaust pipes install pipes into converter On C10 model loosely connect support attaching converter to transmission Install new 0 bolts and clamps at front and rear of converter Check all clearance and tighten clamps and upport Lower vehicle and remove from
425. nd with transmission in Neutral set fast idle cam follower so that tang is on high step of cam 5 Bend tang in or out to obtain fast idle RPM FAST IDLE CAM ADJUSTMENT Fig 11 1 Check fast idle speed and adjust as required 2 Set fast idle cam follower firmly on second stop of cam 3 Rotate and hold choke valve toward closed position by applying force to choke coil rod 4 Insert specified gauge between upper edge of choke valve and inside air horn wall 5 Bend cam to choke rod as required to obtain clearance CHOKE COIL ROD ADJUSTMENT Fig 12 Light Duty Emissions Fig 12 1 Disconnect upper end of choke coil rod at choke valve Completely close choke valve Push up on choke coil rod to its end of travel Bottom of rod should be even with top of lever If adjustment is required bend rod QN Q Rot N Connect rod to choke valve Heavy Duty Emissions Fig 12A 1 Disconnect upper end of choke coil rod at choke valve Completely close choke valve o Push down on choke coil rod to its end of travel Top of rod should even with bottom of hole of choke lever TRUCK SUPP SERVICE GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND INSIDE AIR HORN WALL 2 DOWN ON CHOKE VALVE rov IN END SLOT 1 WITH FAST IDLE ADJUSTMENT MADE CAM FOLLOWER OR FAST IDLE SCREW MUST BE HELO FIRMLY ON SECOND STEP OF FAST IDLE CAM AGAINST HIGH STEP 5
426. nder bore No 1 Carefully assemble Piston No 1 complete with ball and ZERO shoe disc on the front AND ball and NUMBERED shoe disc on the rear over the axial plate Hold front thrust bearing pack tightly against axial plate hub while lifting hub Insert the Piston Assembly into the front cylinder half Fig 51 Repeat this operation for Pistons No 2 and No 3 Fig 52 Without installing any O rings or bushings assemble one end of the new Service discharge cross over tube into the hole in the front cylinder half Fig 53 and 54 Be sure the flattened portion of this tube faces the inside of the compressor to allow for axial plate clearance Fig 54 Now rotate the shaft to position the pistons in a stair step arrangement then carefully place the rear cylinder half over the shaft and start the pistons into the cylinder bores Fig 55 When all three Piston and Ring assemblies are in their respective cylinders align the end of the discharge cross over tube with the hole in the rear half of the cylinder When all parts are in proper alignment tap with a clean wood block and mallet to seat the rear half of the cylinder over the locating dowel pins If necessary clamp the cylinder in Compressing Fixture J 9397 to TRUCK SUPP OVERHAUL SELECTED REAR SHOE DISC SELECTED REAR THRUST RACE THRUST BEARING ZERO THRUST ZERO FRONT SHAFT UPWARD SHOE DISC AND HOLD THE THRUST RACES AND B
427. necessary TRUCK SUPP SERVICE 6 6 ENGINE O m m I sa DU p rmam s ENGINE MISSES AT VARIOUS SPEEDS Inspect carburetor fuel filter for presence of water and or impurities Correct as necessary Check fuel system for leaks plugged fuel lines incorrect fuel pump pressure and or plugged carburetor jets Correct as necessary Check ignition timing Correct as necessary Check for excessive play in distributor shaft Repair or replace as necessary Check for weak or faulty H E I system coil as outlined in Section 6Y of this manual Check inspect and regap spark plugs Replace as necessary 8 Check engine operating temperature Detonation and pre ignition may be caused by using sub standard fuel Correct as necessary Check for weak valve springs and condition of camshaft lobes Repair or replace as necessary Correct as necessary Check operation of exhaust gas recirculation valve Repair or replace as necessary Inspect distributor cap for evidence of carbon tracking Replace if necessary Check for faulty altitude compensator and incorrect carburetor adjustments Correct as necessary Check for vacuum leaks Correct as necessary Check operation of EFE valve as outlined in Section 6T of this manual Repair or replace as necessary ENGINE STALLS Check carburetor for incorrect and or misadjusted idle speed float level leaking needle and seat air valve sticking choke or en
428. ngine manifold is calibrated to hold the choke valve closed when the engine is cold CHOKE AIR VALVE ROD SHAFT LEVER AIR VALVE DASH POT ROD VACUUM BREAK ASSEMBLY SECONDARY LOCKOUT LEVER FAST IDLE CAM FOLLOWER LEVER THERMOSTATIC COIL AND ROD Fig 80 Choke System ENGINE FUEL 6M 59 NOTE To close the choke valve the primary throttle valves have to be opened to allow the fast idle cam follower to by pass the steps on the fast idle cam and come to rest on the highest step of the cam During engine cranking the choke valve is held closed by the tension of the thermostatic coil This restricts air flow through the carburetor to provide a richer starting mixture When the engine starts and is running manifold vacuum applied to the vacuum break unit mounted on the float bowl will open the choke valve to a point where the engine will run without loading or stalling As the thermostatic coil on the engine manifold warms up it relaxes its tension and allows the choke valve to open further because of intake air pushing on the off set choke valve and the counterweight effect of linkage and choke lever Choke valve opening continues until the thermostatic coil is completely relaxed at which point the choke valve is wide open A choke closing assist spring is incorporated in the vacuum break diaphragm plunger stem The spring assists in closing the choke valve along with tension from the choke thermostatic coil
429. nnect vacuum hoses at sensor TRUCK SUPP SERVICE 6M 70 ENGINE FUEL LOWER STOVE NOTE Inboord flange of lower stove must be installed on top of rib of exhaust manifold UPPER STOVE LOWER STOVE WING NUT GASKET POSITION RED SURFACE DOWN 3 EXTENSION GASKET POSITION RED L SURFACE DOWN Fig 15C Air Cleaner 350 400 V8 G amp AIR CLEANER HOSE 350 V8 2 BBL VIEW B Ss BI AIR CLEANER HOSE 350 400 V8 4 BBL VIEW C AMN Vag 2 CARB lt 2N oie e Susan AIR CLEANER 350 400 V8 4 BBL HOSE VIEW D DUCT ASSEMBLY Fig 16C Air Cleaner 454 V8 GASKET POSITION RED SURFACE DOWN EXTENSION GASKET POSITION RED SURFACE DOWN Fig 17C Air Cleaner P20 42 2 Pry up tabs of sensor retaining clip fig 20C Observe position of sensor new sensor must be installed in this same position 3 Remove clip and sensor from air cleaner Replacement 1 Install sensor and gasket assembly in air cleaner in position as noted above Fig 18C Damper Door Thermometer Reading 2 3 ENGINE FUEL 6M 71 WING NUT LOWER STOVE NOTE Inboard flange of lower stove must be installed on top of rib of exhaust manifold UPPER STOVE LOWER STOVE P30 42 P30 32 Press retaining clip on sensor Support the sensor on its sides to prevent damage to the control mechanism at the center Install air cleaner on engine and connect vacuum hoses CARBURETOR AIR IN
430. nt screw located in the cavity next to the power piston The adjustment screw is held from turning by a tension spring beneath the head of the adjustment screw During production flow test the adjustment screw is turned up or down which in turn raises or lowers the power piston and metering rod assembly This very accurately controls the fuel flow between the rods and jets to meet emission requirements CAUTION No attempt should be made to change the A P T adjustment in the field If float bowl replacement 15 required the new bowl assembly will include an adjustment screw pre set by the factory POWER SYSTEM Fig 40 The power system provides extra mixture enrichment for heavy acceleration or high speed operation The richer mixture is supplied through the main metering system in the primary and secondary sides of the carburetor The power system located in the primary side consists of a vacuum piston and spring located in a cylinder connected by a passage to intake manifold vacuum The spring located beneath the vacuum operated power piston tends to push the piston upward against manifold vacuum TRUCK SUPP SERVICE FACTORY METERING ADJUSTMENT SCREW MAIN POWER PISTON DOWN POWER PISTON SPRING CUUM MAIN METERING JETS 2 ENGINE FUEL 6M 35 MAIN WELL AIR BLEEDS BOOST VENTURI s MAIN VENTURI V THROTTLE VALVE MAIN METERING RODS 2 Fig 39 Main Metering System An adjustable par
431. nual Repair or replace as necessary Check operation of diverter valve A LR system Repair or replace as necessary t Check for engine vacuum leaks Correct as necessary ENGINE DIESELING ON SHUT OFF Check base idle speed for improper adjustment and correct as necessary Check ignition timing and reset to specifications if required Check idle mixture setting and correct as necessary d Check accelerator and choke linkage operation and correct as necessary e Check engine operating temperature and correct as necessary f Check thermac valve for sticking and correct as necessary ENGINE DETONATION Check for overadvanced ignition timing and or faulty ignition system and correct as necessary Check for loose or improper application of spark plugs or spark plugs with cracked or broken ceramic cores and replace as necessary Check for the use of sub standard fuel and correct as necessary Check for foreign material in fuel lines and or carburetor and correct as necessary Check for restricted fuel delivery to carburetor pinched lines faulty fuel tank cap or pick up and correct as necessary Check fuel pump operation and replace if necessary Check EFE system operation and repair or replace as necessary h Check EGR system operation and correct as necessary i Check thermostatically controlled air cleaner operation and correct as necessary j Check P C V system operatio
432. nventional Cab C K models 04 Cutaway Van Hi Cube Van G models 05 Chevy Van Vandura 06 Suburban Sportvan Rally Wagon with Panel Rear Doors 16 Blazer Jimmy 32 Motor Home Chassis 42 Forward Control Chassis Step Van Value Von 43 Bonus Cab 63 Crew Cab Chevrolet T Truck CA Dimension Model Type Engine Ordering Code C 10703 E63 t LF5 CA Dimension Model Type 05 Blazer Jimmy Step Van Value Van 07 42 Pickup Chassis Cab 08 or Motor Home Chassis Step Van Value Van 09 56 Suburban Chassis Cab Pickup 10 60 FC Chassis Chevy Van Vandura Sportvan Rally Wagon Chassis Cab Step Van Value Van Body Code ZW9 Base Body Z58 Blazer Jimmy w White Top Z59 Blazer Jimmy w Black Top Z64 RV Cutaway Van E31 Hi Cube Van 10 Steel 96 Wide E32 Step Van Value Van Steel E33 Step Van Value Van Aluminum E34 Hi Cube Van 10 Steel 82 Wide E36 Hi Cube Van 10 Aluminum E38 Hi Cube Van 12 Steel E39 Hi Cube Van 12 Aluminum E55 Suburban w End Gate E62 Stepside Fenderside Pickup E63 Fleetside Wide Side Pickup E94 Beauville Sportvan Rally STX 11 Motor Home Chassis 13 Van Vandura Sportvan Rally Wagon Cutaway Van Hi Cube Van 14 84 FC or Motor Home Chassis Chassis Cab Step Van Value Van 16 Cutaway Van Hi Cube Van 18 Home Ch
433. o as to equalize the springs Also check springs for sag broken leaves or coils Using headlamp aiming device J 25300 aim headlamps as follows VERTICAL AIM SCREW AIM SCREW Right side shown left side is similar Fig 1 Headlamp Aiming Screws Attach a floor slope adapter J 25300 6 fig 2 to each of the headlamp aimers J 25300 1 2 fig 3 The adapters will easily snap into position on the aimer when properly positioned Place aimers with floor slope adapters attached at the center line of each wheel on one side of the vehicle fig 4 Aimers must be placed facing each other Make sure dials of all three adjusting knobs are set at 0 zero Level each aimer unit by turning knob of floor slope adapter fig 2 either clockwise or counterclockwise until the top level vial bubble of the headlamp aimer registers in the centered level position Look into the top sight opening of either the front or rear aiming unit and turn horizontal knob in both directions until the split image 1 aligned Transfer the plus or minus reading indicated on the horizontal dial to the floor slope offset dial fig 3 Then return horizontal dial to a zero setting TRUCK SUPP SERVICE w HORIZONTAL O wm q Tua8rmmT M n n A 12 2 ELECTRICAL BODY AND CHASSIS ADJUSTING KNOB aimer half way between the two readings obtained For instance 5 and 5 Readings Equal 0 Average 4 and 2 Readings
434. o be removed from discharge passage CARBURETOR 6M 7 VENTURE CLUSTER RETURN SPRING ADJUSTABLE PART THROTTLE FUEL INLET Fig 5C Float Bowl 5 Invert carburetor and remove three large throttle body to bowl attaching screws and lockwashers Throttle body and gasket may now be removed Throttle Body 1 Remove the three choke cover attaching screws and retainers then remove thermostatic coil and cover assembly and gasket from choke housing Fig 7C CAUTION not remove cup baffle from beneath thermostatic coil cover because distortion may result 2 Remove baffle plate from inside choke housing Fig 8C 3 Remove the two choke housing attaching screws from inside choke housing then remove choke housing and gasket from throttle body casting PLASTIC MAIN WELL INSERT SPRING RETAINER Fig 6C Removing Spring Retainer TRUCK SUPP OVERHAUL 6M 8 CARBURETOR OFF IDLE IDLE MIXTURE NEEDLE DISCHARGE PORT E lt COVER SCREW 3 CHOKE HOUSING RETAINER 3 IDLE SPEED CHOKE SCREW VACUUM TUBE NI FIXED IDLE AIR BLEED Fig 7C Throttle Body 4 Remove screw from end of intermediate choke shaft and remove intermediate choke lever from shaft Fig 9C Remove inner choke coil lever and shaft assembly from choke housing Remove rubber dust seal from inside choke housing 5 The idle mixture needles have been adjusted and set at the factory and capped
435. o close Continue rotating until index mark lines up with specified point on choke housing ENGINE FUEL 6M 23 4 Tighten choke cover retaining screws 3 MARK ON COVER TO SPECIFIED POINT ON CHOKE HOUSING CARBURETOR MADE INUSA 3 N ROCHESTER LOOSEN THREE PRODUCTS RETAINING SCREWS SET IDLE SPEED SCREW ON HIGHEST STEP OF CAM Fig 29 Automatic Choke Coil Adjustment FAST IDLE CAM ADJUSTMENT Fig 30 1 Turn idle speed screw in until it just contacts low step of fast idle cam Then turn screw in one full turn 2 Place idle speed screw on second step of fast idle cam against highest step 3 Place gauge between upper edge of choke valve and wall of air horn 4 If adjustment is required bend choke lever tang TANG TO ADJUST INSET 2 2 GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND AIR HORN WALL H PLOW IDLE SPEED SCREW ON 2ND STEP OF FAST IDLE CAM AGAINST HIGH STEP INSET 1 Fig 30 Fast Idle Cam Adjustment VACUUM BREAK ADJUSTMENT FIG 31 1 Seat the vacuum break diaphragm using an outside vacuum Source 2 Cover vacuum break bleed hole as shown using a small piece of tape so that diaphragm unit will hold inward and not bleed down TRUCK SUPP SERVICE o CE EQ c 4 rss 6M 24 ENGINE FUEL 3 Place idle speed screw on high step of fast idle cam 4 Remove thermostatic coil and cove
436. o the shaft seal cavity The front head is mounted to the cylinder assembly by four screw and washer assemblies Thrust Washers One thrust washer is used on the rear end of the crankshaft between the rear eccentric and the rear of the cylinder A belleville washer sandwiched between two thrust washers at the front of the shaft between the front eccentric and the front head controls the lateral thrust tolerance of the shaft and cylinder assembly The two thrust washers have tangs and are assembled with the tangs facing inward to engage and cause the thrust and belleville washer assembly to rotate as a unit and not separately OIL CHARGE Refer to the oil charge chart in Figure 5 for A 6 and R 4 compressor oil charge SYSTEM CONTROLS General 1976 CK Series Truck Fig 6 Heating and Air Conditioning mode selection has been simplified by the addition of a new Maximum Mode position to the previous six mode control With the Temperature lever set to the extreme cold position and the mode selector lever positioned in MAX maximum cooling is attained and High blower speed is automatically selected The new MAX mode setting as well as the other cooling settings NORM and BI LEVEL have been grouped under an A C heading The VENT and HEATER settings have been grouped under an ECONOMY heading Selector Lever The system selector lever air control lever determines the mode of operation When the system selector lever is placed in A
437. of compressor shell with 525 viscosity refrigerant oil and position shell on internal mechanism resting on O ring seal TRUCK SUPP OVERHAUL 10 11 12 13 14 19 Front Discharge Valve Plate Assembly SUPPORT BLOCK J 21352 Fig 59 Installing Front Discharge Valve Plate Suction Reed Larger Dia Hole Rear Discharge Valve Plate Front Discharge Valve Plate Fig 60 Front and Rear Discharge Valve Plates Using flat side of a small screwdriver gently position O ring in around circumference of internal mechanism until compressor shell slides down over internal mechanism As shell slides down line up oil sump with oil intake tube hole Fig 63 Holding Support Block invert assembly and place back into Holding Fixture with front end of shaft down Remove Support Block Install new dowel pins in rear cylinder half if previously removed Install new O ring in oil pick up tube cavity Lubricate oil pick up tube with 525 viscosity refrigerant oil and install into cavity rotating compressor mechanism to align tube with hole in shell baffle Fig 64 Install new O ring and bushing on rear end of discharge cross over tube See Fig 53 16 17 18 19 20 AIR CONDITIONING COMPRESSOR 1 23 Front Head Casting Front Dischorge Valve Plate Assembly Fig 61 Installing Front Head Casting Front Head O Ring Fig 62 Front Head O Ring Installed
438. oil from all sealing surfaces on rear head casting webs and examine sealing surfaces Fig 25 any damage is observed the head should be replaced Remove suction screen and examine for any damage or contamination Clean or replace if necessary Paint an identifying mark on exposed face of inner and outer oil pump gears and then remove gears Identifying marks are to assure that gears if reused will be installed on identical position Remove and discard rear head to shell O ring Carefully remove rear discharge valve plate assembly Use two small screwdrivers under reed retainers to pry up on assembly Fig 26 not position screwdrivers between reeds and reed seats Examine valve reeds and seats Replace entire assembly if any reeds or seats are damaged Using two small screwdrivers carefully remove rear suction reed Fig 27 Do not pry up on horseshoe shaped reed valves TRUCK SUPP OVERHAUL 1 12 AIR CONDITIONING COMPRESSOR SUPERHEAT SHUTOFF 4 switcH 4 SURFACES UCTION SCREEN REAR HEAD SHELL TO HEAD O RING OIL PUMP ROTORS REAR DISCHARGE VALVE PLATE ASSEMBLY DISCHARGE REEDS Fig 26 Removing Rear Discharge Valve Plate Reor Suction Reed Fig 27 Removing Rear Suction Reed 12 Examine reeds for damage and replace if necessary 13 Using Oil Pick Up Tube Remover J 5139 Fig 28 remove oil pick up tube Remove O ring from oil inlet 14 Loosen
439. olt Nuts 22 ft Ibs 22 ft Ibs 22 ft Ibs 22 ft Ibs 22 ft Ibs Absorber to Axles Stud Nut 80 ft Ibs Absorber to Tie Rod Stud Nut Power Steering Pump Mounting Bracket Bolts V 8 25 ft Ibs 1 6 18 ft Ibs 45 ft Ibs L 6 18 ft Ibs V 8 25 ft Ibs L 6 V 8 Ibs Ibs Power Stering Pump Mounting Bolts V 8 25 ft Ibs L 6 18 ft Ibs V 8 25 ft Ibs L 6 18 ft Ibs V 8 25 ft Ibs 18 ft 25 ft L 6 18 ft Ibs L 6 18 ft Ibs 18 ft V 8 25 ft Ibs L 6 Ibs V 8 25 ft Ibs Reservoir Hose Clamp Screws E Power Steering Pump 1 6 18 ft Ibs L 6 18 ft Ibs 1 6 18 ft Ibs 1 6 18 ft Ibs 1 6 18 ft Ibs Mounting Stud Nut V 8 25 ft Ibs V 8 25 ft Ibs V 8 25 ft Ibs V 8 25 ft Ibs V 8 25 ft Ibs Power Steering Hose Clamp Screws 15 in Ibs 15 in Ibs 15 in Ibs 15 in Ibs 15 in 16 25 ft Ibs 25 ft ibs 25 ft Ibs 165 in Ibs Power Steering Hose Clamp Nut 150 in Ibs 150 Ibs 150 in Ibs Power Steering Hose Clip Nut 150 in Ibs ees tin 18 ft Ibs Oil Cooler to Radiator Support 30 in Ibs Reservoir Attaching Screws W saa 15 in Ibs Plus additional torque required to align castellation with cotter pin hole i
440. om top of air horn ring to top of pump rod 4 If adjustment is required bend rod INTERMEDIATE CHOKE ROD ADJUSTMENT Fig 28 1 Remove thermostatic cover coil gasket and inside baffle plate assembly by removing three attaching screws and retainers 2 Place idle speed screw on the highest step of fast idle cam 3 Close choke valve by pushing up on intermediate choke lever TRUCK SUPP SERVICE 3 GAUGE FROM TOP OF AIR HORN RING TO TOP OF PUMP ROD 7 BACK OUT IDLE SPEED ADJUSTING SCREW BEND ROD x HOLD THROTTLE VALVES COMPLETELY CLOSED Fig 27 Pump Rod Adjustment 4 Edge of coil lever inside choke housing must line up with edge of plug gauge 5 Bend intermediate choke rod at point shown to adjust 6 Install thermostatic coil and cover referring to automatic choke coil adjustment 8 BEND ROD MERE TO 7 ADJUST SEE INSET EDGE OF coit LEVER MUST LINE UP WITH EDGE OF 120 PLUG GAUGE IN HOLE INSIDE LOSE CHOKE VALVE CHOKE HOUSING Y PUSHING UP ON LEVER REMOVE THERMOSTATIC VER All ad Se alo ONG AGE LOW IDLE SPEED SCREW ON HIGHEST STEP OF FAST IDLE CAM Fig 28 Intermediate Choke Rod Adjustment AUTOMATIC CHOKE COIL ADJUSTMENT Fig 29 1 Place idle speed screw on the highest step of fast idle cam 2 Loosen thermostatic choke coil cover retaining screws 3 Rotate choke cover against coil tension until choke valve begins t
441. on Charging Station to a refrigerant drum standing in an upright TRUCK SUPP OVERHAUL FRONT HEAD SHELL TO HEAD O RING CYLINDER _ ASSEMBLYI Fig 66 A 6 Shell To Front Head O Ring Installation position and open valve on drum Connect Charging Station HIGH and LOW pressure lines to corresponding fittings on Test Plate J 9625 using J 5420 Gage Adapters NOTE Suction port of compressor has large internal opening Discharge port has small internal opening into compressor Open LOW pressure control HIGH pressure control and REFRIGERANT control on Charging Station to allow refrigerant vapor to flow into compressor Using electronic type Leak Detector check for leaks at pressure relief valve superheat switch compressor shell to cylinder compressor front head seal and also rear head seal and oil charge port on 6 compressor and compressor shaft seal After checking shut off LOW pressure control and HIGH pressure control on Charging Station If an external leak is present perform the necessary corrective measures and recheck for leaks to make certain the leak has been corrected 10 11 12 13 14 AIR CONDITIONING COMPRESSOR 1 25 SLIGHTLY ROTATE FRONT HEAD IF NECESSARY TO LINE UP LOCATORE PINS AND HOLES quan Fig 67 Installing Rear Head Loosen the manifold gage hose connections to the Gage Adapters J 5420 connected to the LOW and HIGH
442. on sufficiently for brake drum to clear the pipe Remove the two pull back springs Remove the guide plate from anchor pin Remove shoe hold down cups springs and washers from hold down pins remove pins Pull brake shoe and lining assemblies away from anchor pin and remove the strut and spring Lift the brake shoes and linings with the adjusting nut and bolt and connecting spring off the flange plate Move the shoes toward each other until the adjusting bolt and connecting spring drop off Remove the clip holding the brake lever to the primary shoe shoe with short lining Compress the spring on the brake cable and remove the cable from the lever If necessary to remove the anchor pin straighten the washer from pin hex and reinforcement Remove reinforcement and washer with anchor pin If necessary to remove the cable compress tangs on cable and pull assembly out of the hole in the flange plate If necessary to remove the flange plate remove the transmission flange nut and transmission output flange Remove bolts holding the flange plate to bearing retainer and remove the flange plate Inspection Replace any worn or broken parts Installation l Place the flange plate in position on the rear bearing retainer and fasten with four bolts Torque bolts to 24 foot pounds CAUTION See Caution on Page 1 of this section 2 Install transmission output flange on spline o
443. onnect the electrical harness at the switch connector Remove the screw attaching the sensing element clamp and remove the clamp Insulating material around sensing element may be removed at this point Remove the two screws attaching the switch body to the evaporator inlet line bracket and remove the switch and sensing element To replace reverse steps 1 to 3 NOTE Insulating material removed from sensing element must be replaced with a suitable insulating compound When replacing sensing element clamp tighten screw securely enough to provide intimate contact between sensing element and inlet tube Do NOT over tighten HEATER AIR DISTRIBUTOR AND EXTENSION DUCT G MODEL Replacement 1 10 en sp Disconnect battery ground cable Remove engine cover Remove evaporator blower shield Remove shield bracket Remove left floor outlet deflector and bracket Loosen steering column to instrument panel reinforcement screws Remove one screw Torque both screws on installation Disconnect speedometer cable at meter Remove instrument panel to lower reinforcement attaching screws Move instrument panel assembly rearward Disconnect radio antenna and electrical connector Support instrument panel at right visor Disconnect electrical connector at brake switch Remove blower evaporator support bracket to door pillar and forward engine housing attaching screws Move rearward to gain access TRU
444. oose line connections and look for bends or kinks in lines 2 Disconnect fuel pipe carburetor Disconnect distributor to coil primary wire so that engine be cranked without firing Place suitable container at end of pipe and crank engine a few revolutions If little or no gasoline flows from open end of pipe then fuel pipe is clogged or pump is inoperative Before removing pump disconnect fuel pipe at gas tank and outlet pipe and blow through them with an air hose to make sure they are clear Reconnect pipes and retest while cranking engine TIGHTEN TO 15 POUND FEET t Yx S TIGHTEN TO 215 POUND FEET Fig 22C Fuel Pump 250 L6 3 If fuel flows from pump in good volume from pipe at carburetor check fuel delivery pressure to be certain that pump is operating within specified limits as follows a Attach a fuel pump pressure test gauge to disconnected end of pipe b Run engine at approximately 450 1 000 rpm using gasoline in carburetor bowl and note reading on pressure gauge TRUCK SUPP SERVICE TIGHTEN TO 15 POUND FEET X TIGHTEN TO 927 15 POUND FEET HIN TIGHTEN TO 15 POUND FEET Fig 23C Fuel Pump 262 L6 c If pump is operating properly the pressure will be within specifications and will remain constant at 4 BBL CARBURETOR 2 BBL CARBURETOR PUSH ROD TENA GASKET TIGHTEN TO 36 IN LBS TIGHTEN e VIEW 22 FT LBS Fig 24C
445. ore in case fig 21R Allow spring to drop into place at bottom of Second Third shift rail bore Insert lower detent plug in detent bore on top of spring TRUCK SUPP OVERHAUL I5 16 18 Install output shaft assembly in case Install shifter fork shafts in their case bores with the pivot lug facing up NOTE Shifter fork shafts are interchangeable Install 15 roller bearings in clutch shaft bore Use vaseline or equivalent to hold bearings in place CAUTION not use chassis grease or a similar heavy grease in clutch shaft bore Heavy grease will plug the lubricant holes in the shaft and prevent proper lubrication of the roller bear ng Install blocking ring on clutch gear and place clutch gear through top of case and position in front case bore Be sure First Reverse sleeve and gear is in Neutral centered position on hub so gear end of sleeve will clear notch in top of case when output shaft assembly is installed Assemble the clutch gear to the output shaft Move Second Third sleeve rearward to Second gear position and position Second Third shifter fork in groove of sleeve Be sure setscrew hold in shifter fork is facing up NOTE Second Third fork is the smaller of the two shifter forks Engage Second Third shifter fork in shifter fork shaft and insert Second Third shift rail through front case bore and into shifter fork NOTE Tapered end of rail faces front of case Fig
446. ose the return line to the power steering pump is connected to this port The pressure port and the gear port each contains an aluminum tube seat insert The accumulator valve components are assembled in the accumulator valve bore which is machined in the housing This bore is connected by passages to the accumulator and to the pressure port The integral spring accumulator fig 7 is used in conjunction with the hydraulic brake booster The accumulator piston assembly and spring are assembled in the accumulator bore which is machined in the housing PRESSURE PORT RETURN PORT PEDAL ROD ACCUMULATOR GEAR PORT OUTPUT PUSH ROD MOUNTING BRACKET BOOSTER POWER SECTION Fig 6 Hydro Boost With Integral Accumulator WARNING Do not attempt to disassemble or cut into the accumulator The accumulator contains a spring compressed under high pressure BLEEDING HYDRO BOOST POWER STEERING HYDRAULIC SYSTEM The following procedure should be used to bleed the power steering hydraulic system on hydro boost vehicles NOTE If the power steering fluid has foamed due to low fluid level it will be necessary to park the vehicle for approximately one hour reservoir cap loose so that the foam can dissipate 1 Raise the front of the vehicle on a hoist so that the tires are clear of the floor 2 Check reservoir and fill with GM Power Steering Fluid or equivalent NOTE Leave the reservoir cap off during entire bleed procedure
447. ot within the specified Throttle Return Control TRC speed range then turn the screw on the actuator plunger in the appropriate direction and repeat step No 4 until the specified TRC speed range is obtained SERVICE OPERATIONS CARBURETOR REPLACEMENT FIG 59 Removal Flooding stumble on acceleration and other performance complaints are in many instances caused by presence of dirt water or other foreign matter in carburetor To aid in diagnosis carburetor should be carefully removed from engine without draining fuel from bowl Contents of fuel bowl may then be examined for contamination as carburetor is disassembled Check filter 1 Remove air cleaner and gasket 2 Disconnect fuel and vacuum lines from carburetor 3 Disconnect fresh air hose choke hose hot air choke or electrical connection electric choke from choke system 4 Disconnect accelerator linkage 5 If equipped with automatic downshift cable disconnect cable 6 Remove carburetor attaching bolts and carburetor remove 7 Remove insulator Installation It is good shop practice to fill carburetor bowl with a small amount of unleaded fuel before installing carburetor This reduces strain of starting motor and battery and reduce the possibility of backfiring while attempting to start engine The carburetor float and intake needle and seat can also be checked Operate throttle lever several times and check discharge from pump jets before installin
448. out of place when lowering rear head into position Fig 67 If rear head assembly will not slide down over dowels in internal mechanism twist front head assembly back and forth very slightly by hand until rear head drops over dowel pins 25 26 27 28 29 30 3l INNER GEAR GEAR TEETH 3 O CLOCK Fig 65 Positioning Oil Pump Gears Install nuts on threaded shell studs and tighten evenly to 19 25 Ib ft torque using a 0 50 Ib ft torque wrench Invert compressor in Holding Fixture and install compressor shaft seal as described in Compressor Shaft Seal Replacement procedure Install compressor clutch coil and housing assembly as described in Compressor Clutch Coil and Housing Asm Replacement procedure Install compressor pulley and bearing assembly as described in Pulley and Bearing Replacement procedure Install compressor clutch plate and hub assembly as described in Compressor Clutch Plate and Hub Asm Replacement procedure Add required amount of 525 viscosity refrigerant oil Refer to compressor oil charge Figure 5 Section 1A this manual Check for external and internal leaks as described in the following Compressor Leak Testing procedure COMPRESSOR LEAK TESTING EXTERNAL AND INTERNAL A 6 and R 4 Compressors Bench Check Procedure I 2 Install Test Plate J 9625 on rear head of compressor Attach center hose of gage manifold set
449. ove clutch shaft front bearing using tool J 6654 01 and tool J 8433 1 fig 7R NOTE It may be necessary to alternate the tightening of the bolts between tools J 6654 01 and J 8433 1 to remove the front bearing Remove large locating snap ring from rear bearing and smaller retaining snap ring from output shaft NOTE It may be necessary to place a screwdriver or a piece of bar stock between the case and the first reverse sleeve and gear assembly This will hold the output shaft assembly in place while removing the rear bearing Remove rear bearing from output shaft using tool J 8157 01 fig 8R Remove set screw from First Reverse shifter fork and slide shift rail out rear of case Shift First Reverse sleeve and gear all the way forward and rotate First Reverse shifter fork upward and out of case Remove First Reverse Detent plug from case Shift Second Third Shifter fork rearward to gain access to setscrew remove setscrew rotate shift rail 90 with pliers to clear bottom detent plug and remove interlock plug with magnet fig 9R Using a long thin punch 1 4 inch diameter or less insert through access hole in rear case to drive out shift rail and expansion plug located in shift rail bore at front of case Rotate second third shifter fork upward and out of case 18 Remove the bottom detent plug and short detent spring from case Separate clutch gear from output shaft and remove output s
450. ove tape from vacuum break end cover 6 TO ADJUST 5 PLACE GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND AIR HORN WALL PUSH UP ON CHOKE COIL LEVER ROD IN END OF SLOT VACUUM SOURCE TO SEAT DIAPHRAGM PLUG PURGE BLEED PLUNGER UNTIL n HOLE WITH MASKING IT SEATS TAPE OVER END COVER REMOVE AFTER ADJUSTMENT CAM FOLLOWER ON HIGHEST STEP OF FAST IDLE CAM Fig 13 Primary Vacuum Break Adjustment TRUCK SUPP SERVICE ne 6M 10 ENGINE FUEL AUXILIARY VACUUM BREAK ADJUSTMENT Fig 14 Light Duty Emissions 1 Position cam follower on highest step of fast idle cam 2 Using an outside vacuum source apply vacuum to auxiliary vacuum break diaphragm until plunger is fully seated 3 With vacuum break diaphragm in fully seated position insert specified gauge between upper edge of choke valve and inner air horn wall 4 PLACE SPECIFIED GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND INNER AIR HORN WALL 2 USE OUTSIDE VACUUM SOURCE TO SEAT DIAPHRAG 3 DIAPHRAGM PLUNGER IN UNTIL SEATED 1 CAM FOLLOWER ON HIGHEST STEP OF CAM Fig 14 Auxiliary Vacuum Break Adjustment 4 If adjustment is required bend link between vacuum break and choke valve CHOKE UNLOADER ADJUSTMENT Fig 15 1 Hold down on choke valve by applying a light force to choke coil lever 2 Rotate throttle valve to wide open position 3 Ins
451. oved Align choke valve tighten two retaining screws and stake securely or use Loctite or equivalent Install air horn to float bowl by lowering gently onto float bow until seated Install three long and three short air horn to float bowl attaching screws and lockwashers Tighten screws securely Install the primary choke vacuum break diaphragm assembly under the two short air horn screws next to the thermostatic coil lever Connect the choke vacuum break diaphragm link to slotted diaphragm plunger stem and install lever to the end of the choke shaft using retaining screw Tighten all screws securely Install the choke vacuum break diaphragm hose to the diaphragm on air horn and tube on float bowl Assemble choke rod into the slot in the upper choke lever End of rod points away from air horn casting when installed properly Install ower end of choke rod into fast idle cam Steps on fast idle cam should face fast idle tang on throttle lever Install fast idle cam to boss on float bowl with attaching screw Tighten securely Install auxiliary vacuum break diaphragm link attached to the choke lever to slot in the diaphragm plunger stem Then install the auxiliary vacuum break diaphragm unit to air horn using two attaching screws Tighten securely ROCHESTER 2GC INDEX Greneral Disassembly Cleaning and Inspection Assembly Specials
452. owl gasket Torque air horn to float bowl using proper tightening procedure Carburetor loose on manifold Torque carburetor to manifold bolts 10 14 ft Ibs Probl NO POWER ON HEAVY ACCELERATION robiem OR AT HIGH SPEED Check Adjust throttle linkage to obtain wide open throttle in carburetor Carburetor throttle valve not going wide open by pushing accelerator pedal to floor Dirty or plugged fuel filter Replace with a new filter element Power system not operating Check power valve for free up and down movement Float level too low 1 Check and reset float level as specified in carburetor over haul section Float not dropping far enough into float bowl Check for binding float hanger and for proper float align ment in float bowl Main metering jet dirty plugged or incorrect part 1 If the main metering jet is plugged or dirty and excessive dirt is in fuel bowl carburetor should be completely dis assembled and cleaned Problem ENGINE STARTS HARD WHEN HOT Choke valve not opening completely 1 Check for binding choke valve and or linkage Clean and free up or replace parts as necessary Do not oil choke linkage 2 Check and adjust choke coil rod Engine flooded Carburetor flooding See procedure under Engine cranks will not start No fuet in carburetor 1 Check fuel pump Run pressure and volume test 2 Check float needle for sticking in seat or binding float Leaking f
453. p Tail Lamp Clear sese candi ia stove me tenute eere 20 Amp Directional Signal Indicator Lamp Stop Lamp Traffic inrer Ms cr 15 Instrument Cluster Lamp Heater Dial Lamp Radio Dial Lamp Cruise Control Lamp Windshield Wiper Switch lamps Lesser dn 4 Amp Windshield Wiper Washer RR 25 Amp Cruise Control Rear Window Aux Fuel Tank Tachome ter Back up Lamp Directional Signal Indicator Lamp Directional Signal Lamp Headlamp Buzzer 15 Amp P TRUCK Heatert Air Conditioningt isse 25 Amp Instrument Cluster Lamp Windshield Wiper Switch GHG odes netus oed hoes eae esa aay Re tri TER tes ore 3 Amp Directional Signal Indicator Lamp Stop Lamp Traffic 15 Fuel Gauge Brake Warning Lamp 3 Amp License Plate Lamp Parking Lamp Side Marker Lamp Tail Lamp Clearance Lamp Identification Lamp b Amp Windshield Washer Wiper 2 2222222222 2 1 25 Amp Cigarette Lightert Clock Courtesyt Dome Lamp 5 Amp Auxiliary Batteryt Back up Lamp Radio 15 Amp Idle Stop Solenoid Cruise Control Directional Signal Lamp Time Delay Relay Emission Control Solenoid Transmission Downshift M40 22 0 10 Amp In line fuses are located in the auxiliary heater circuits C K P mod els and un
454. p on one of the yokes and support the shaft horizontally Avoid damaging the slip yoke sealing surface Nicks may damage the bushing or cut the seal lip 1 Support the propshaft in a horizontal position in line with the base plate of a press Place the universal joint so that the lower ear of the shaft yoke is supported on a 1 1 8 socket Place the cross press J 9522 3 on the open horizontal bearing cups and press the lower bearing cup out of the yoke ear as shown in figure 5 This will shear the plastic retaining the lower bearing cup 2 If the bearing cup is not completely removed lift the cross and insert Spacer J 9522 5 between the seal and bearing cup being removed as shown in figure 6 Complete the removal of the bearing cup by pressing it out of the yoke 3 Rotate the propshaft shear the opposite plastic retainer and press the opposite bearing cup out of the yoke as before using Spacer J 9522 CROSS PRESS 39522 3 1 7 SOCKET TO SUFFORT Fig 5 Pressing Out Bearing Cup TRUCK SUPP SERVICE SPACER J 9522 5 BEARING cup Fig 6 Using Spacer to Remove Bearing Cup 4 Disengage cross from yoke and remove NOTE Production universal joints cannot be reassembled There are no bearing retainer grooves in production bearing cups Discard all universal joint parts removed 5 Remove the remains of the sheared plastic bearing retainer from the ears of the yoke This will aid in reassembly of the serv
455. p system can be made as scored or distorted replace the pump plunger follows With the engine off remove air cleaner and look 2 Check the pump discharge ball for proper seating and into the carburetor bores and observe pump stream while location The pump discharge ball is located in a cavity briskly opening throttle valve A full stream of fuel should next to the pump well To check for proper seating emit from pump jet and strike near the center of the remove air horn and gasket and fill cavity with fuel No venturi area leak down should occur Restake and replace check ball if leaking Make sure discharge ball spring and re tainer are properly installed Dirt in pump passages or pump jet Clean and Blow out with compressed air Fuel level Check for sticking float needle or binding float Free up or replace parts as necessary Check and reset float level as specified in carburetor overhaul section Leaking air horn to float bowl gasket Torque air horn to float bow using proper tightening procedure Carburetor loose on manifold Torque carburetor to manifold bolts 10 14 ft Ibs Probl NO POWER ON HEAVY ACCELERATION robiem OR AT HIGH SPEED Check Adjust throttle linkage to obtain wide open throttle in carburetor Carburetor throttle valve not going wide open by pushing accelerator pedal to floor Dirty or plugged fuel filter Replace with a new filter element Power system not ope
456. park plugs The capacitor in the distributor is for radio noise suppression The module automatically controls the dwell period stretching it with increasing engine speed The HEI system also features a longer spark duration made possible by the higher amount of energy stored in the coil primary This is desirable for firing lean and EGR diluted mixtures IGNITION COIL CONNECT TACHOMETER FROM THIS TERMINAL TO GROUND SOME TACHOMETERS MUST CONNECT FROM THIS TERMINAL TO ENERGIZER POSITIVE SOME TACHOMETERS MAY NOT WORK AT ALL CONSULT TACHOMETER HIGH ENERGY MANUFACTURER IGNITION DISTRIBUTOR N CONNECTOR BAT TERMINAL CONNECTED TO IGNITION SWITCH VACUUM E UNIT ve HOUSING gt LATCH 4 Fig 2i 6 Cylinder HEI Distributor Ignition Coil In the 8 cylinder HEI system the igntion coil is built into the distributor cap In the 6 cylinder HEI system the ignition coil is mounted externally The coil is somewhat smaller physically than a conventional coil but has more primary and secondary windings It is built more like a true transformer with the windings surrounded by the laminated iron core conventional coil has the iron core inside the windings Although the HEI coil operates in basically the same way as a conventional coil it is more effective in generating higher secondary voltage when the primary circuit is broken Electronic Module The electronic modu
457. pecific service methods that can damage the vehicle or render it unsafe are stated in this service manual It is also important to understand these warnings are not exhaustive We could not possibly know evaluate and advise the service trade of all conceivable ways in which service might be done or of the possible hazardous consequences of each way Consequently we have not undertaken any such broad evaluation Accordingly anyone who uses a service procedure or tool which is not recommended by the manufacturer must first satisfy himself thoroughly that neither his safety nor vehicle safety will be jeopardized by the service method he selects C 1976 General Motors Corporation 1976 10 30 SERIES TRUCK CHASSIS SERVICE and OVERHAUL MANUAL SUPPLEMENT FOREWORD This manual has been prepared as a supplement to the 1974 Light Duty Truck Service and Overhaul Manuals It covers in separate sections diagnosis maintenance adjustments service operations and overhaul procedures for the 1976 10 30 Series truck models Complete wiring diagrams for the vehicles covered in this manual will be found in the separate 1976 Truck Wiring Diagram booklet ST 352 76 Any reference to brand names in this manual is intended merely as an example of the types of lubricants tools mate rials etc recommended for use In all cases an equivalent may be used All information illustrations and specifications contained in this literature are based o
458. pense and possibly prevent a repeat complaint When a fuel pump is suspected of not performing properly the following tests must be made NOTE Do not remove the pump for any of these inspec tions or tests Be certain sufficient gasoline is in the tank INITIAL INSPECTION 1 Be certain all fittings and connections are tight and cannot leak fuel between the pump and the carburetor or air between the gas tank and the pump 2 Look for kinks in the fuel lines 3 With engine idling look for leaks a In the line between the pump and the carburetor b Atthe diaphragm flange on the pump c Atthe breather holes in the pump casting d At the sheet metal cover pump and its fittings If leaks are evident in the lines or fittings tighten or replace as necessary If the fuel pump leaks diaphragm flange sheet metal cover or pump casting breather holes replace the pump If the above steps do not cure the problem proceed to the next test VACUUM TEST This will determine if the pump has the ability to pump fuel 1 Disconnect the fuel line at the carburetor Install a rubber hose on to the fuel line and run it back into the gas tank 2 Disconnect the inlet fuel line at the pump Fasten the inlet line in an up position so fuel will not run out Install a vacuum gage on to the inlet of the pump 3 With engine idling using fuel in the carburetor float bowl the vacuum should be at least 12 Hg 4 If the vacuum i
459. plug by carefully tapping on the flat surace of the retainer Fig 8 CAUTION 77e projections must not extend beyond the spacer when the retainer is sealed to prevent TRUCK SUPP OVERHAUL STEERING 9 3 BEARING WITH IDENTIFICATION TOWARD TOOL Fig 6 Installing Bearing Fig 5 Removing Bearing and Seal interference with valve body The spacer must be free thrust bearing adjustment in service is simplified to rotate Power Steering Gear Adjustment Procedure Recommended procedure 1 Drain power steering fluid from gear by rotating the stub shaft full travel in both directions several times Adjustment of the steering gear in the vehicle is discouraged IL d di a ter plug lock nut Fig 9 and because of the difficulty encountered in adjusting the worm 0 gad remove adjuster S ae thrust bearing preload and the confusing effects of the _ 4 hydraulic fluid in the gear Since a gear adjustment is made 3 Using spanner wrench J 7624 turn the adjuster plug in clockwise until the plug and thrust bearings are firmly only as a correction and not as a periodic adjustment it is i bottomed approximately 20 foot pounds Fig 11 better to take the extra time and make the adjustment correctly the first time 4 Mark the housing even with one of the holes in the face Since a handling stability complaint can be caused by of the adjuster plug Fig 12 improperly adjusted worm bearings a
460. ps 7 67 4 CP Cargo lamp 1 1142 21 Radio Dial lamp 1 1816 3 CP AM FM 1 216 Cruise Control lamp 1 53 Courtesy lamp 1 1003 15 CP Windshield wiper switch 1 161 1 Clock 1 168 3 CP Rear Identification 10 1895 2 Underhood lamp 1 93 15 CP Seat belt warning 1 168 3 CP Cargo dome lamp 2 211 2 12 CP 1 On CA KA 10 35 instrument clusters only 3 lamps used on instrument cluster on P models or C K w o gauges 3 Double filament sealed beam 60W high beam 50W tow beam 2 lamps used with step bumper and P models 4 required on P models 6 1157 2 2 24 on C K models 7 Wideside Pickup SPECIFICATIONS 27 LAMP BULB DATA G TRUCK Used in Quantity Trade Power Dome lamps 2 211 2 12 CP Oil pressure indicator lamp 1 168 3 CP Generator indicator lamp 1 168 3 CP Instrument cluster lamps 3 168 JEP Headlamp beam indicator lamp 1 168 3 CP Park directional signal lamps 2 1157 3 32 Tail stop lamps 2 1157 3 32 License lamp 1 67 4 CP Head Lamps 2 6014 50 60W Temperature Indicator Lamp 1 168 3 CP Directional signal indicator lamp 2 168 3 CP Marker lamps 4 168 3 CP Brake warning indicator lamp 1 168 3 CP Back up lamp 2 1156 32 CP Radio dial lamp 1 1893 2 CP Heater or A C Contro 1 1895 2 CP Transmission Control w Tilt Wheel 1 1445 0 7 CP Cruise control 1 53 1 W S wiper Switch lamp 1 161 1 1Double filament sealed beam 60W high beam
461. r eec eee 15 6 Theory of Operation oannes roce itle 15 1 Op ash Tat 15 6 Cruise Master Units eerie onere epos 15 2 Column Mounted Engagement Switch 15 6 Maintenance and Adjustments 15 3 Diagnosis ou eet Rn A Re PERRA 15 6 E 15 3 Electrical System Troubleshooting 15 6 Servo U EE 15 3 Engagement Switch 2 21 15 6 Brake Release Switches sess 15 4 Harness Test 15 6 Electric OR PIOS 15 4 Servo and Vacuum System 15 7 MACUUMM cinis 15 4 System Diagnosis Charts sss 15 9 Component Part Replacement 15 6 GENERAL DESCRIPTION The Cruise Master is a speed control system which employs engine manifold vacuum to power the throttle servo unit The servo moves the throttle when speed adjustment is necessary by receiving a varying amount of controlled vacuum from the regulator unit The speedometer cable from the transmission drives the regulator and a cable from the regulator drives the instrument panel speedometer The engagement of the regulator unit is controlled by an engagement switch located at the end of the turn signal lever On Dealer Installed Cruise Systems the engage switch is mounted on the
462. r Fork C Ring Lock Clip Spring Reverse Shifter Fork Shifter Shaft Hole Plunger 1st 2nd Shifter Fork Hold reverse fork in position and push shaft through yoke Install split pin in fork and shaft then push fork in neutral position Hold 3rd and 4th fork in position and push shaft through yoke but not through front support bore Place two 2 interlock balls in cross bore in front support boss between reverse and 3rd and 4th shifter shaft Install the interlock pin in the 3rd and 4th shifter shaft hole and grease to hold in place Push 3rd and 4th 11 12 Interlock Plunger Reverse Interlock 1st 2nd Shifter Shaft Interlock Pin Cover Gasket Fig 1X Cover Assembly Exploded View TRUCK SUPP OVERHAUL shaft through fork and cover bore keeping both balls and pin in position between shafts until retaining holes line up in fork and shaft Install retaining pin and move to neutral position Place two 2 interlock balls between the Ist and 2nd shift shaft and 3rd and 4th shifter shaft in the cross bore of the front support boss Hold 1st and 2nd fork in position and push shaft through cover bore in fork until retainer hole and fork line up with hole in shaft Install retainer pin and move to neutral position Install new shifter shaft hole expansion plugs and expand in place MAINSHAFT ASSEMBLY Disassembly Fig 3X 1 Remove first speed gear and thrust washer MANUAL TRANSMISSION 7M 13 Re
463. r Hub ALIGNMENT KEYS 3 SPRING UNDER LIP OF Fig 14R Second Third Synchronizer Assembly Install First Reverse sleeve and gear half way onto hub with gear end of sleeve facing rear of shaft Index sleeve to hub with marks made during disassembly Install spring in First Reverse hub Make sure spring is bottomed in hub and covers all three key slots Position three synchronizer keys in hub with small ends in hub slots and large ends inside hub Push keys fully into hub so they seat on spring Then slide First Reverse sleeve and gear over keys until the keys engage in the TRUCK SUPP OVERHAUL Fig 15R Installing Extension Housing Bushing Fig 16R Installing Extension Housing Seal synchronizer sleeve fig 13R Place first gear blocking ring on tapered surface of gear Install First gear on output shaft Rotate gear until notches in blocking ring engages keys in First Reverse hub Install tabbed thrust washer sharp edge facing out and retaining snap ring on output shaft fig 18R MANUAL TRANSMISSION 7M 7 OIL RETURN TOOL SLOT J 25233 FRONT BEARING CAP Fig 17R Installing Clutch Bearing Retainer Seal TABBED THRUST WASHER SHARP EDGE MUST FACE OUT Fig 18R Installing Tabbed Thrust Washer 6 Place second gear blocking ring on tapered surface of gear and install second gear on output shaft with tapered surface of gear facing front of output shaft fig 19R 7 Install Se
464. r Tab over end of stud in direction of arrow Fig 4C Servo Composite C K Trucks TRUCK SUPP SERVICE ACCESSORIES 15 5 ELECTRICAL RELEASE AND STOP LAMP RELEASE BRAKE PEDAL BRACKET RELEASE VALVE STRIKER STRIKER amp eese new B BRAKE PEDAL e V33 TILT COLUMN G TRUCK C K TRUCK Fig 5C Release Switches Valve and Brackets BRAKE PEDAL IN NORMAL POSITION Y BRAKE PEDAL Eos 7 Hing WHEN VACUUM VALVE 5 OPENS INSTALLATION OF SELF ADJUSTING VACUUM RELEASE VALVE Install mounting clip into bracket Depress brake pedal amp push valve into clip until shoulder on valve asm bottoms out against clip Adjust valve by bringing pedal to normal position so that valve is open when pedal is depressed to dimension shown Fig 6C Vacuum Valve TRUCK SUPP SERVICE 15 6 ACCESSORIES st COMPONENT PART REPLACEMENT REGULATOR Replacement 1 Disconnect battery ground cable 2 Disconnect speedometer cables at regulator 3 Disconnect vacuum and wiring harness at regulator body 4 Remove regulator to bracket screws and remove regulator 5 To install reverse Steps 1 4 above SERVO Replacement 1 Disconnect battery ground cable 2 Disconnect vacuum line at servo can 3 Remove servo cover Disconnect ball chain from cable retainer 4 Remove servo to bracket screw s and remove servo 5 To install reverse Steps 1 4 above 6 Adjust the
465. r and hold choke coil lever inside choke housing towards the closed choke position 5 Gauge between upper edge of choke valve and air horn wall 6 Bend vacuum break rod at point shown to adjust 7 After adjustment remove piece of tape covering small bleed hole at rear of vacuum break diaphragm unit Reconnect vacuum hose 8 Install thermostatic coil and cover referring to automatic choke coil adjustment 3 GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND SEAT DIAPHRAGM 4 PLUNGER USING 2 es 2 BEND LINK A SEE INSET PLUG PURGE BLEED HOLE WITH A PIECE _ OF MASKING So m i NOTE PLACE IDLE SPEED ns SCREW ON HIGH STEP OF e RE IURE FAST IDLE CAM Fig 31 Vacuum Break Adjustment CHOKE UNLOADER ADJUSTMENT Fig 32 1 With throttle valves held in wide open position place choke valve toward closed position 2 Place specified gauge between upper edge of choke valve and air horn casting to check clearance 3 If adjustment is required bend tang on throttle lever 2 GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND AIR HORN PER 1 THROTTLE VALVES WIDE OPEN 2 3 BEND TANG TO ADJUST 2 Fig 32 Unloader Adjustment SERVICE OPERATIONS CARBURETOR REPLACEMENT Fig 33 Removal Flooding stumble on acceleration and other performance complaints are in many instances caused by presence of dirt water or other foreign matter in carbur
466. r damage which could cause leakage Inspect fuel cap for correct sealing ability and indications of physical damage Replace any damaged or malfunctioning parts C 15 AIR CLEANER ELEMENT Replace the engine air cleaner element under normal operating conditions every 30 000 miles The PCV filter should be replaced at the same interval Operation of vehicle in dusty areas will necessitate more frequent replacements CAUTION Do not operate the engine without the air cleaner unless temporary removal is necessary during repair or maintenance of the vehicle When the air cleaner 15 removed backfiring can cause fire the engine compartment TRUCK SUPP SERVICE GENERAL INFORMATION AND LUBRICATION 0 17 RECOMMENDED FLUIDS amp LUBRICANTS Power steering system and pump reservoir Differential standard Differential Positraction FLUID LUBRICANT GM power steering fluid Part No 1050017 if not available use automatic transmission fluid or equivalent SAE 80W or SAE 80W 90 GL 5 gear lubricant SAE 80W in Canada Lubricant GM Part No 1050081 Manual Steering Gear Manual transmission Brake system and master cylinder Clutch linkage Man trans only a Pivot points b Push rod to clutch fork joint and cross shaft pressure fitting Manual transmission shift linkage column shift Lubricant GM Part No 1051052 SAE 80W or 80 90 GL 5 ge
467. r system in carburetor not functioning properly Power valve sticking in up position Free up or replace as necessary in carburetor overhaul section 1 Check for dirt in the needle and seat Test using suction by mouth or needle seat tester If defective replace needle and seat assembly with factory matched set 2 Check for loaded float High fuel level in carburetor or carburetor flooding 3 Re set carburetor float as specified in carburetor overhaul section 4 If excessive dirt is present in the carburetor bowl the carburetor should be cleaned Run engine at RPM where nozzle is feeding fuel Observe pump jet If fuel is feeding from jet check pump discharge ball for proper seating by filling cavity above ball with fuel to level of casting No leak down should occur with discharge ball in place Re stake or replace leaking check ball defective spring or retainer Fuel being pulled from accelerator system into venturi through pump jet Air bleeds or fuel passages in carburetor dirty or plugged Clean carburetor or overhaul as necessary TRUCK SUPP SERVICE 6M 54 ENGINE FUEL n YM 2A 4MV QUADRAJET CARBURETOR INDEX General Description cte 6M 54 Air Valve Dashpot Adjustment 6M 61 Theory of eee
468. r those vehicles normally operated in Canada use SAE 80W GL 5 Gear Lubricant only TRANSMISSION SHIFT LINKAGE MANUAL AND AUTOMATIC Every 7 500 miles or 6 months lubricate shift linkage and on Manual transmission floor control lever contacting faces with water resistant EP chassis lubricant which meets General Motors Specification GM6031 M Clutch The clutch pedal free travel should be checked at regular intervals Lubricate the clutch cross shaft at fitting on Series 10 Forward Control models also lubricate the clutch linkage idler lever at fitting every 7 500 miles or 6 months with GENERAL INFORMATION AND LUBRICATION 0 9 water resistant EP chassis lubricant which meets General Motors Specification GM 6031 M REAR AXLES Standard Every 6 months or 7 500 miles whichever occurs first check lubricant level and add lubricant if necessary to fill to level of filler plug hole Use SAE 80W or SAE 80W 90 GL 5 Gear Lubricant For those vehicles normally operated in Canada use SAE 80W GL 5 Gear Lubricant Positive Locking or Positraction Every 6 months or 7 500 miles whichever occurs first check lubricant level and add lubricant if necessary to fill to level of filler plug hole Drain and refill at first 15 000 miles then maintain same as standard axle but use only the special positraction differential lubricant PROPELLER SHAFT SLIP JOINTS Propeller shaft slip joints should be lubricated every 7 500
469. rating Check power valve for free up and down movement Float level too low 1 Check and reset float level as specified in carburetor over haul section Float not dropping far enough into float bowl Check for binding float hanger and for proper float align ment in float bowl Main metering jet dirty plugged or incorrect part 1 If the main metering jet is plugged or dirty and excessive dirt is in fuel bowl carburetor should be completely dis assembled and cleaned Problem ENGINE STARTS HARD WHEN HOT Choke valve not opening completely 1 Check for binding choke valve and or linkage Clean and free up or replace parts as necessary Do not oil choke linkage 2 Check and adjust choke coil rod Engine flooded Carburetor flooding See procedure under Engine cranks will not start No fuel in carburetor 1 Check fuel pump Run pressure and volume test 2 Check float needle for sticking in seat or binding float Leaking float bowl Fill bowl with fuel and look for leaks TRUCK SUPP SERVICE ENGINE FUEL 6M 31 M4MC M4ME QUADRAJET CARBURETOR INDEX General Description 6M 31 Fast Idle Cam Choke Rod Adjustment 6 41 Theory qol OD6eFatlon rre one erue ener enne 6M 32 Air Valve Dashpot Adjustment 6M 42 Float NS ose trente 6M 32 Front Vacuum Break Adjustment 6M 42 Idie Syet aaa erre
470. rcial use when the engine is regularly idled for prolonged periods or when vehicle is used for towing the oil pan should be drained and the strainer cleaned every 15 000 miles Drain fluid immediately after operation before it has had an apportunity to cool WARNING Transmission fluid temperature can exceed 350F SHIFT CONTROLS Column Shift Linkage G Series Fig 2G 1 The shift tube and lever assembly must be free in the mast jacket 2 Set transmission lever C in neutral position by one of the following optional methods NOTE Obtain neutral position by moving transmission lever C counter clockwise to L1 detent then clockwise three detent positions to neutral or obtain neutral position by moving transmission lever C clockwise to the park detent then counter clockwise two detents to neutral 3 Set the column shift lever in neutral position This is obtained by rotating shift lever until it locks into mechanical stop in the column assembly NOTE Do not use indicator pointer as a reference to position the shift lever 4 Attach rod A to shaft assembly B as shown fig 2G 5 Slide swivel D and clamp E onto rod A align the column shift lever and loosely attach as shown 6 Hold column lever against neutral stop park position side 7 Tighten nut F to 18 foot pounds 8 Readjust indicator needle if necessary to agree with the transmission detent positions 9 Readj
471. rder to have good engine performance during warm up and be able to pass Federal exhaust emission standards the electric choke must function properly Possible reasons for the choke not operating properly are listed below 1 No engine oil pressure 2 Malfunctioning oil pressure switch 3 No current to oil pressure switch due to a Burned out 15 amp radio idle stop fuse b Broken wire to switch 18 brown double white 4 No current between choke coil and oil pressure switch due to a Broken 18 light blue lead wire b Wire terminal not locked on coil terminal c Ground circuit incomplete between grounding plate of choke assembly and housing 5 Failed choke coil assembly A voltmeter or continuity light may be used to check the circuits for continuity to the oil pressure switch and the choke coil If it is suspected that the choke coil assembly has failed the following check may be made 1 Remove coil from carburetor and cool to room temperature above 60 F 2 Attach a jumper wire between positive battery terminal and terminal of coil assembly Attach a second jumper wire between negative battery terminal and grounding plate of choke coil assembly 3 The tang of the coil should rotate 45 in 54 to 90 seconds 4 If coil fails to rotate or exceeds the above timing specification replace coil assembly 5 If coil is within above timing specification then coil is good and problem is elsewhere 6 Reinst
472. re Step number 12 should read 12 Install intermediate clutch plates a All models except CL and CZ Lubricate with transmission oil two 2 flat steel and one 1 waved steel plates and three 3 composition faced intermediate clutch plates and install starting with waved steel plate and alternating composition faced and flat steel plates fig 16B b Models CL and CZ Lubricate with transmission oil three 3 flat steel and three 3 composition faced intermediate clutch plates and install starting with flat steel and alternating composition faced and flat steel plates Fig 16B NOTE The models CL and CZ intermediate composition faced plates are different from the other models Refer to parts catalog for correct usage CASE EXTENSION ASSEMBLY 1 Install new case extension housing to case gasket on extension housing Model CL uses a seal between the extension housing and case extension 2 Attach extension housing to case using attaching bolts and or studs Torque bolts to 20 25 ft Ibs TRUCK SUPP OVERHAUL 7A 12 AUTOMATIC TRANSMISSION SS STEEL PLATES 3 Fig 16B Installing Intermediate Backing Plate and Clutch Plates NOTE Models CA CG and CR use two 2 studs at 5 o clock and 7 o clock positions when viewed from the rear of case and transmission in vehicle These studs are for the installation of the catalytic converter Torque the studs to 20 25 ft lbs 3 If necessary install a new se
473. replace thrust washer 4 Install shaft tool J 25232 in bore of countergear and load a row of needle bearing 25 in each end of gear Use heavy grease or equivalent to hold them in place Install one needle bearing retainer on each end of gear 5 Position countergear thrust washer in case use vaseline or equivalent to hold washers in place NOTE Be sure to engage locating tabs on thrust washer in locating slots in case 6 Insert countershaft into bore at rear of case just far enough to hold rear thrust washer from being displaced when the countergear is installed 7 Align bore in countergear with countershaft and front thrust washer then start countershaft into countergear Before countershaft is completely installed make sure that roll pin hole in countershaft is aligned with hole in case When holes are aligned tap countershaft into place remove tool J 25232 fig 5R 8 Measure countershaft end play by inserting feeler gauge between thrust washer and countergear End play should be 0 004 to 0 018 inch If end play exceeds 0 018 inch remove gear and replace thrust washers 9 After correct end play has been obtained install roll pin in case UPPER DETENT SPRING LONG 4 FRONT OF CASE UPPER DETENT PLUG di SETSCREW BORE FIRST REVERSE SHIFT RAIL SECOND THIRD SHIFT RAIL LOWER DETENT SPRING SHORT Fig 21R Installation Sequence Detent Plugs and Springs 10 Lower shorter detent spring in detent b
474. replacement discard all of them and install the 16 service direct clutch release springs 8 Inspect housing for free operation of check ball Assembly Assembly procedure caution should read CAUTION The direct clutch housing for the CL and CZ models use the 6 plate clutch assembly Fig 11B Production built transmissions now use a direct clutch housing with a check ball see Fig 10B If the housing requires replacement and the replacement housing does not contain a check ball replace the direct clutch piston with the service piston which has a check ball Models CL and CZ service piston has 2 check balls EITHER THE DIRECT CLUTCH HOUSING AND OR THE PISTON MUST CONTAIN A CHECK BALL S AUTOMATIC TRANSMISSION 7A 9 FOR IDENTIFICATION CHAMFER FOR a NO CHAMFER AND OR GROOVE IDENTIFICATION DIRECT CLUTCH HOUSING DIRECT CLUTCH HOUSING FOR 6 PLATE CLUTCH PACK FOR 4 OR 5 PLATE PACK Fig 11B Direct Clutch Housing Plate Pack CHECK BALL DIRECT CLUTCH HOUSING Fig 12B Direct Clutch Housing Assembly procedure step number 5 should read 5 Install fourteen 14 springs into piston leaving two pockets diametrically opposite with no springs Assembly procedure step number 8 should read 8 Install direct clutch plates a Model install four 4 composition faced and four 4 flat steel clutch plates starting with a flat steel plate and alternating composition faced and
475. result fuel begins to discharge from the lower idle air bleed holes and continues to do so throughout operation of the part throttle to wide open throttle ranges supplementing the main discharge nozzle delivery EXHAUST GAS RECIRCULATION E G R Fig 38 An Exhaust Gas Recirculation E G R system is used on light duty emission vehicles and California heavy duty emission vehicle with 454 V8 engine to control oxides of nitrogen NOx emissions The E G R valve is operated by a vacuum signal taken from the carburetor Two punched ports one located just above the throttle valve and the other near the upper edge of the throttle body casting provide a timed vacuum signal port for E G R valve operation in the off idle and part throttle ranges of the carburetor The purpose of the E G R system is to supply a metered amount of exhaust gases to the combustion mixtures and lower combustion temperatures thereby reducing oxides of nitrogen during these ranges of engine operation The port system operates as follows TRUCK SUPP SERVICE 6M 34 ENGINE FUEL As the throttle valve is opened beyond the idle position the first vacuum port for the E G R system is exposed to manifold vacuum to supply a vacuum signal to the E G R valve To control the vacuum signal at the lower port the upper port bleeds air into the vacuum channel and modulates the amount of vacuum signal supplied by the lower E G R port In this manner the E G R valve
476. result in a lower pump up pressure and disqualify a good pumping compressor 16 Observe the reading on the HIGH pressure gage at the completion of the tenth revolution of the compressor The pressure reading for a good pumping compressor should be 50 p s i or above for the R 4 and 60 p s i or above for the 6 compressor pressure reading of less than 45 p s i for the R 4 or 50 p s i for the 6 would indicate one or more suction and or discharge valves leaking an internal leak or an inoperative valve and the compressor should be disassembled and checked for cause of leak Repair as needed reassemble and repeat the pump up test A MY A IG M dime MEE Id Am 0 Externally leak test with the electronic type Leak Detector 17 When the pressure pump up test is completed release the air pressure from the HIGH side and remove the Gage Adapters J 5420 and Test Plate J 9625 18 On the R 4 tilt the compressor so that the compressor suction and discharge ports are down Drain the oil from the compressor On the A 6 remove oil charge screw and drain the oil sump 19 Allow the compressor to drain for 10 minutes then charge with the proper amount of oil The oil may be poured into the suction port NOTE If further assembly or processing is required a shipping plate or Test Plate J 9625 should be installed to keep out air dirt and moisture until t
477. rews Center the choke valve before tightening choke valve screws Tighten choke valve screws and stake lightly in place Check choke and shaft for freedom of movement If removed install the outer pump shaft and lever assembly into air horn casting Make sure the plastic washer is in place before installing the outer pump shaft and lever assembly Install the pump plunger to the inner lever and retain with clip provided in the repair kit End of pump plunger shaft should point inward towards center of carburetor when installed correctly Then install inner pump lever onto the pump shaft and tighten set screws securely Position the float needle seat gasket on the needle seat and install seat in the air horn Tighten securely Install the power piston assembly into the air horn casting and lightly stake the retaining washer to casting Make sure the piston travels up and down freely and is not bent Install fuel inlet baffle next to needle seat Make sure baffle is seated in grooves in air horn casting Install air horn gasket onto air horn casting Install float needle into needle seat Then install float assembly on air horn and insert hinge pin Check float action and for free movement of needle in the seat Check float level and drop adjustments Float Level Adjustment With air horn inverted gasket in place and needle seated measure distance from lip at toe of float to air horn gasket Adjust f
478. richment system and secondary vacuum break operation Adjust repair or replace as necessary Inspect carburetor fuel filter for presence of water and or impurities Correct as necessary Check H E I system as outlined in Section 6Y of this manual Check inspect and regap spark plugs Repiace as necessary Check distributor spark advance mechanism for proper operation Repair or replace as necessary Inspect exhaust system for restrictions Correct as necessary Check carburetor mounting gasket for air leaks Repair as necessary Check and adjust valve lash i Check for burned warped or sticking valves Repair or replace as necessary Check engine operating Check engine for low compression Repair as necessary temperature Correct as necessary Check for loose corroded or leaking wiring connections bulk head connectors etc Repair as necessary Check operation of exhaust gas recirculation system Repair or replace as necessary Check fuel system for leaks and or obstructions Repair as necessary Check for vacuum leaks Correct as necessary Check operation of EFE valve as outlined in Section 6T of this manual Repair or replace as necessary TRUCK SUPP SERVICE ENGINE 6 7 ENGINE HAS LOW POWER Check for weak or faulty H E I system coil as outlined in Section 6Y of this manual Check ignition timing Correct as necessary Check for excessive play in
479. ring and screw plug in case Install poppet plate spring gasket and plug if not installed during reassembly of range box Install shift levers on the range box shifter shaft if not left on linkage in vehicle Torque all bolts locknuts and plugs except filler plug to specifications Fill transfer case to proper level with specified lubricant Install and tighten filler plug to specifications TRUCK SUPP OVERHAUL SECTION 7A AUTOMATIC TRANSMISSIONS CONTENTS OF THIS SECTION Turbo Hydra Matic 350 Transmission Turbo Hydra Matic 375 400 475 Transmission 7A 3 TURBO HYDRA MATIC 350 TRANSMISSION DISASSEMBLY 1 Install Holding Fixture J 8763 02 on transmission and place into Holding Tool base J 3289 20 with converter facing upward NOTE Cleanliness is an important factor in the overhaul of the transmission Before attempting any disassembly operation the exterior of the case should be thoroughly cleaned to prevent the possibility of dirt entering the transmission internal mechanism During disassembly all parts should be thoroughly cleaned in cleaning fluid and then air dried Wiping cloths or rags should not be used to dry parts CAUTION Do not use solvents which could damage rubber seals or clutch facings 2 With transmission in holding fixture remove torque converter assembly 3 Remove vacuum modulator assembly attaching bolt and retainer 4 Remove vacuum modulator assembly O
480. ring while attempting to start engine A small supply of fuel will enable carburetor to be filled and the operation of float and intake needle and seat to be checked Operate throttle lever several times and check discharge from pump jets before installing carburetor 1 Be certain throttle body and intake manifold sealing surfaces are clean 2 Install carburetor insulator TRUCK SUPP SERVICE INSULATOR o f gt CAS TORQUE SEQUENCE TIGHTEN N NC NUTS TO 36 IN LBS THEN TO 18 FT LBS conie gt I Ba e HEAT STOVE Fig 16 Carburetor Choke and Heat Stove Install carburetor over manifold studs Install vacuum and fuel lines at carburetor Install attaching nuts and tighten securely Tighten fuel and vacuum lines Connect accelerator linkage Connect choke coil rod and idle stop solenoid electrical connector OQ t A UC Guide vent tube into rocker cover and install air cleaner 10 Refer to Maintenance and Adjustment and adjust low and curb idle speeds FUEL FILTER REPLACEMENT Fig 17 A plugged fuel filter will restrict fuel flow into carburetor and will result in a loss of engine power 1 Disconnect fuel line connection at inlet fuel filter nut Remove inlet fuel filter nut from carburetor Remove filter element and spring Install element spring and filter element in carburetor ot N Install new gasket on
481. rn the adjustment 2 Air valves must be closed completely screw on the vacuum break plunger lever 3 Place specified gauge between air valve dashpot and end 7 After adjustment install vacuum hose to vacuum break of slot in air valve lever unit 4 Bend air valve dashpot rod at point shown if necessary 8 Install thermostatic cover and coil referring to to adjust automatic choke coil adjustment FRONT VACUUM BREAK ADJUSTMENT REAR VACUUM BREAK ADJUSTMENT Fig 50 Fig 49 MAME 1 Loosen three retaining screws and remove thermostatic 1 Loosen three retaining screws and remove thermostatic cover and coil assembly from choke housing cover and coil assembly from choke housing 2 Place cam follower lever on highest step of fast idle cam 2 Place cam follower lever on highest step of fast idle cam 3 Seat the front vacuum diaphragm using an outside 3 Seat the rear vacuum diaphragm using an outside vacuum source vacuum source TRUCK SUPP SERVICE 4 PLACE GAUGE BETWEEN UPPER EDGE OF CHOKE VALVE AND NSIDE WALL OF AIR HORN NOTE HOLO GAUGE VERTICALLY 2 SEAT DIAPHRAGM USING OUTSIDE VACUUM SOURCE 5 TURN SCREW TO ADJUST 1 PLACE CAM FOLLOWER ON HIGHEST STEP OF FAST IDLE CAM 3 PUSH INSIDE CHOKE COIL LEVER COUNTERCLOCK WISE UNTIL TANG ON VACUUM BREAK LEVER CONTACTS TANG ON VACUUM BREAK PLUNGER STEM Fig 49 Front Vacuum Break Adjustment NOTE HOLD GAUGE VERTICALLY GAUGE BETWEEN AIA HORN W
482. ront and rear faces for burrs and if present dress them off with a fine mill file Front and Rear Bearings 1 Wash the front and rear ball bearings thoroughly in a cleaning solvent 2 Blow out bearings with compressed air CAUTION Do not allow the bearings to spin turn them slowly by hand Spinning bearings will damage the race and balls 3 Make sure bearings are clean then lubricate with light engine oil and check them for roughness by slowly turning the race by hand TRUCK SUPP OVERHAUL 1 2 3 4 5 6 7 8 9 MAINSHAFT ROLLER BEARINGS 2 0 amp 3RD SYNCHRONIZER RETAINING RING SYNCHRONIZER BLOCKER RINGS 2 0 amp 3RD SYNCHRONIZER SPRING 2ND amp 3RD SYNCHRONIZER SLEEVE 2ND 8 3RD SYNCHRONIZER KEYS 2ND amp SYNCHRONIZER HUB SECOND SPEED GEAR 15 SPEED GEAR RETAINING RING 1ST SPEED GEAR TABBED WASHER IST SPEED GEAR REVERSE SYNCHRONIZER SPRING IST REVERSE SYNCHRONIZER SLEEVE amp GEAR REVERSE SYNCHRONIZER KEYS IST amp REVERSE SYNCHRONIZER 1ST amp REVERSE SYNCHRONIZER RETAINING RING REAR BEARING RETAINING RING TRANSMISSION MAINSHAFT REVERSE SYNCHRONIZER ASSEMBLY ACCESS COVER BOLTS ACCESS COVER ACCESS COVER GASKET BEARING RETAINER TO CASE BOLTS BEARING RETAINER CLUTCH GEAR GASKET CLUTCH GEAR BEARING RETAINER OUSZSSUSSNS SEAL ASSEMBLY CLUTCH GEAR BEARING RETAINER CLUTCH GEAR BEARING RETAINING RING C
483. rotor and assembly parts Fig 79 If pulley rim mounting screws and washers were removed in Step 2 only clutch rotor and bearing assembly will be removed for replacement The clutch coil and housing assembly is pressed onto front head of compressor with an interference fit and will not be removed unless pulley rim mounting screws are left securely in place and pulley rim pulls coil and housing assembly off with total clutch rotor and pulley rim assembly Fig 80 CLUTCH ROTOR BEARING REPLACEMENT Removal Fig 76 Installing Seal Seat O Ring O ring groove Rotate installer tool to seat O ring and remove tool Inspect the internal neck area for cleanliness and proper O ring positioning PR P P 1 Perform Compressor Clutch Rotor and Bearing 3 Dip new shaft seal O ring and seal face in clean 525 Assembly Removal and remove the pulley rim Viscosity oil and carefully engage shaft seal assembly with locking tangs of seal remover and installer J 9392 Fig 8 4 Install shaft seal protector J 22974 over the end of compressor shaft and slide shaft seal onto compressor mounting screws as described in Step 2 Placerotor and bearing assembly on blocks Fig 82 and drive bearing out of rotor hub with rotor bearing remover and rotor assembly installer J 25029 It will not be necessary to remove the staking at the rear of the TRUCK SUPP OVERHAUL CLUTCH ROTOR BEARING RETAINING RING Fig 77 Removing Be
484. rottle valves are opened engine manifold vacuum low pressure is applied directly beneath the air valves Atmospheric pressure on top of the air valves forces the air valves to open against spring tension and allows metered air to pass through the secondary bores of the carburetor When the secondary throttle valves begin to open the accelerating well ports are exposed to manifold vacuum The ports immediately start to feed fuel from the accelerating wells and continue to feed fuel until the fuel in the well is gone This prevents a momentary leanness as the air valve opens and before the secondary nozzles begin to feed fuel TRUCK SUPP SERVICE 6M 36 ENGINE FUEL SECONDARY METERING RODS 2 ACCELERATOR AIR WELL amp TUBE VALVE ACCELERATING METERING WELL PORT ROD LEVER BOOST VENTURI MAIN WELL AIR FACTORY METERING BLEEDS ADJUSTMENT SCREW NOTE SIDE FUEL ENTRY MAIN B main FUEL f DISCHARGE NOZZLE THROTTLE VALVE MAIN POWER PISTON UP POWER PISTON SPRING VACUUM SECONDARY THROTTLE VALVE METERING DISC MAIN METERING MAIN RODS 2 METERING PASSAGE JETS 2 Fig 40 Power System As the air vaives open a plastic eccentric cam attached to the center of the air valve shaft rotates and through the metering rod lever lifts the secondary metering rods out of the secondary orifice plates The fuel mixture travels from the main wells through the secondary discharge nozzles where it
485. rvice procedure not contained herein LIGHTING SYSTEM MAINTENANCE AND ADJUSTMENTS HEADLAMP ADJUSTMENT HEADLAMP AIMING The headlamps must be properly aimed in order to provide maximum allowable road illumination Headlamps should be checked for proper aim at new car predelivery every 12 months after installing a new sealed beam unit or if front end sheet metal is adjusted or repaired Some state and local authorities have special or additional requirements for headlamp aiming and these requirements should be followed Horizontal and vertical aiming of each sealed beam unit is provided by two adjusting screws which move the mounting ring in the body against the tension of the coil spring fig 1 Both circular and rectangular headlamps are aimed in the same manner There is no adjustment for focus since the sealed beam unit is set for proper focus during manufacturing assembly Before headlamp aiming process begins it is necessary to prepare vehicle as follows 1 Remove any large amounts of mud or ice from underside of fenders 2 Place vehicle on a fairly level flat surface It is not necessary that this surface be exactly level 3 Make sure tires are properly inflated 4 Clean headlamp lenses 5 Fuel tank should be one half full If heavy load is normally carried in load area it should remain there 6 Driver should remain in vehicle or an equivalent weight placed in driver s seat 7 Rock vehicle sideways s
486. ry 6 Months or 7 500 Miles Chassis Lubrication e Fluid Levels Check Engine Oil Change At 1st Oil Chg Then Every 214 4 Oil Filter Change Tire Rotation Steel Belted Radial 6 Rear Axle Lube Change Air Conditioning Check Every 12 Months or 15 000 Miles Cooling System Check Pee ee Coolant Change amp Hose Replacement Wheel Bearing Repack Auto Trans Fluid amp Filter Change Manual Steering Gear Check lutch Cross Shaft Lubrication Owner Safety Checks Tire and Wheel Inspection Exhaust System Check Drive Belt Check Belt Replacement Suspension and Steering Check Brake and Power Steering Check rum Brake and Parking Brake Check Throttle Linkage Check nderbody Flush amp Check umper Check hermo Controlled Air Cleaner Check arburetor Choke Check ngine Idle Speed Adjustment FE Valve Check arburetor Mounting Torque Fuel Filter Replacement Vacuum Advance System amp Hoses Check PCV System Check PCV Valve amp Filter Replacement Idle Stop Solenoid Check Spark Plug Wires Check Spark Plug Replacement Engine Timing Adjustment amp Dist Check Every 24 Months or 30 000 Miles ECS System Check amp Filter Replacement Fuel Cap Tank and Lines Check Every 30 000 Miles Air Cleaner Element Replacement e Also A Safety Service Also An Emission Control Service Every 30 000 Miles o 1 Every 6 Months or 7 500 Miles A gt gt M O IN Every 12
487. s 6 Connect hoses to TVS ports 7 Add coolant as required THERMAL VACUUM SWITCH TVS L6 Oil Temperature The TVS is located on right hand oil gallery Replacement 1 Disconnect hoses at TVS ports 2 Remove TVS switch TRUCK SUPP SERVICE 6 6 EMISSION CONTROL SYSTEMS 3 Install TVS switch 4 Connect hoses to TVS ports ACTUATOR AND ROD ASSEMBLY The actuator and rod assembly is located on a bracket attached to right exhaust manifold on V8 engines figs 6 and 7 and on left side attached to exhaust manifold on L6 engine fig 8 POWER ACTUATOR ACTUATOR ROD Fig 6 Actuator and Rod 350 400 V8 Replacement 1 Disconnect hose from actuator 2 Remove 2 nuts attaching actuator to bracket 3 Disconnect rod from valve and remove actuator and rod 4 Install actuator and rod reversing steps 1 through 3 Tighten nuts to 25 pound inches EXHAUST HEAT VALVE V8 Replacement 1 Remove crossover exhaust pipe Refer to Section 8 for removal and installation 2 Disconnect rod from valve 3 Remove valve 4 Install valve and connect rod 5 Install crossover exhaust pipe POWER ACTUATOR ACTUATOR ROD a EXHAUST HEAT VALVE EXHAUST PIPE POWER ACTUATOR Fig 8 Actuator and Rod L6 EXHAUST HEAT VALVE L6 Replacement 1 Remove 2 nuts attaching actuator bracket to valve and exhaust manifold 2 Remove bracket and disconnect rod from valve 3 Remove 2 additional nuts from valve
488. s 7 Add oil if necessary 8 Lower the vehicle and turn wheels right and left on the ground 9 Check oil level and refill as required 10 If oil is extremely foamy allow vehicle to stand a few minutes with engine off and repeat above procedure a Check belt tightness and check for a bent pulley Pulley should not wobble with engine running b Check to make sure hoses are not touching any other parts of the vehicle particularly sheet metal c Check oil level filling to proper level if necessary following operations 1 through 10 This step and Step d are extremely important as low oil level and or air in the oil are the most frequent causes of objectionable pump noises TRUCK SUPP SERVICE STEERING 9 5 P SERIES MOTOR HOME STEERING CONNECTING ROD IDLER ARM ASSEMBLY STEERING GEAR ASSEMBLY STEERING GEAR MOUNTING BRACKET TIE ROD ASSEMBLY STEERING GEAR ASSEMBLY 2 PITMAN ARM ING a Y STEERING ARM G SERIES e Fig 4 Steering Linkage d Check the presence of air in the oil Air will show up 11 The presence of trapped air in the system will cause the as milky appearing oil If air is present attempt to fluid level in the pump to rise when the engine is turned bleed system as described in operations 1 through 10 off Continue to bleed system until this condition no longer occurs TRUCK SUPP SERVICE 9 6 STEERING NOTE Equal thread lengths must
489. s 3 5 Pints Chevrolet 10 1 2 5 4 Pints Dana 10 1 2 7 2 Pints Dana 9 3 4 6 0 Pints 12 1 4 DIFFERENTIAL SPECIFICATIONS 10 1 2 Chevrolet Gear Backlash Preferred 003 Pinion Bearing Preload In Lbs New 15 30 Bolt Torques Ft Lbs Differential 55 Bearing Caps A Except where noted otherwise Bolt Torques Ft Lbs 4 Filler Plugs Differential Pinion Lock Drive Pinion Nut Differential Carrier to Axle Housing Differential Bearing Adjusting Lock Pinion Bearing Cage To Carrier Thrust Pad Lock Nut Brake Backing Plate Axle Shaft To Hub Bolts n _ 14 0 Pints 10 1 2 Chevrolet TU 35 105 1 m 115 85 20 15 65 165 05 155 Torque as necessary to obtain correct preload TRUCK SUPP SPECS SPECIFICATIONS 7 TORQUE SPECIFICATIONS FT LBS CONT D GIO 120 Spring to Axle U Bolt Nuts G20 120 G30 150 170 Exc w 3 4 Bolt 200 W 3 4 Bolt Leaf Spring Front Bushing Bolt 90 135 G316 90 Rear Shackle Bolt 90 135 0316 90 Shock Absorber Upper Attachment PIO 25 20 140 30 50 Lower Attachment Propeller Shaft To Rear Axle Strap Rear Axle U Bolt Bearing Support to Hanger Hanger to Frame Rear Stabilizer to Anchor Plate 20 30 90 Ft Lbs when tight
490. s except P30 32 models Refer to the 1974 Light Duty Truck Service Manual for brake pedal adjustment on P30 32 models BOOSTER INSTALLATION Refer to Figure 8 for booster installation HYDRAULIC LINE ROUTING Refer to Figures 9 thru 11 for typical hydraulic line routings Mini Master Cylinder 1976 G Series trucks with Hydroboost and all P Series trucks will incorporate new Bendix mini master cylinders fig 12 Due to the new size the G series master cylinder is mounted straight out from the dash rather than laterally in the vehicle as in 1975 fig 8 Replacement procedures remain basically unchanged to those described in the 1974 Truck Service Manual On four wheel disc brake vehicles JF9 the brake warning light switch fig 6 is an integral part of the mini master cylinder assembly it is non serviceable A brake line distribution block 1s located on the frame crossmember It is not a combination valve its only function is to act as a distributor for attaching front and rear brake lines The component parts of the mini master cylinder differ from those of a conventional master cylinder although their functions are essentially the same A disassembled master cylinder is shown in Figure 13 Note that when the master cylinder is in the released position fig 14 the actuator of the secondary piston and the BRAKES 5 11 actuator of the primary piston are in contact with the compensating valve stems which project into the
491. s less than 12 Hg replace pump If the vacuum is okay proceed to the next test NOTE Do not be concerned if vacuum drops off after the engine is stopped Many pumps have valves with a bleed hole that allows vapors to bleed back to the gasoline tank PRESSURE TEST This will determine if the pump can deliver fuel at the proper pressure to the carburetor 1 Reconnect the inlet fuel line to the pump 2 Reconnect the fuel line at the carburetor Idle engine for two minutes so the carburetor float bowl can be refilled This step may be omitted if enough fuel remains in the carburetor after vacuum test 3 Disconnect fuel line at the carburetor and install a pressure gage into the end of this fuel line If the pump has a vapor return line pinch the line closed 4 With the engine idling using fuel in the carburetor float bowl the pressure gage when held at the level of the pump outlet should read at least 3 psi 5 If the pressure is less than this value determine if the line from the pump to the carburetor is restricted If this line is restricted replace or clean it If the line is not restricted remove the pump and install a new one 6 If the pressure is okay determine if fuel can be pulled up to the pump Disconnect the fuel line at both the fuel pump inlet and the gas tank outlet Blow air into the fuel pump end of the line to determine if fuel can flow through this line NOTE Failure to disconnect the fuel
492. s well as an improper 5 Measure back CCW direction 1 2 inch 12 5 gear over center adjustment it is necessary that the steering millimetres and place a second mark on the housing gear assembly be removed from the vehicle and both thrust Fig 13 bearing and over center preload be checked and corrected 6 Turn adjuster plug Gounterclockwiseuimtilthe hole in as necessary An in vehicle check of the steering gear will 5 the f the adj lug whi i not pin point a thrust bearing looseness e face of the adjuster plug which was even with the first mark is in line with second mark Fig 14 Thrust Bearing Adjustment 7 Tighten lock nut securely Hold or have held adjuster If a gear is known to contain the new thrust bearing parts plug to maintain alignment of hole with mark Fig 15 TRUCK SUPP OVERHAUL 9 4 STEERING Fig 7 Installing Adjuster Plug Seal Fig 9 Loosening Lock Nut Fig 10 Removing Lock Nut Fig 8 Installing Retainer TRUCK SUPP OVERHAUL STEERING 9 5 Fig 15 Tighten Lock Nut Fig 13 Measure Back and Remark Housing TRUCK SUPP OVERHAUL 9 6 STEERING 1 PUMP PULLEY REMOVER J 25034 2 PUMP PULLEY INSTALLER 25033 Fig 16 Special Tools TRUCK SUPP OVERHAUL SPECIFICATIONS HEATING AND AIR CONDITIONING SECTION 1A HEATER Amps REN System Capacities Volts Cold Cold Refrigerant 19 Blower Motor C K Four Season System 3 lbs 12 oz
493. sary n Check oil pressure switch for leakage Replace if necessary EXCESSIVE OIL CONSUMPTION DUE TO OIL ENTERING COMBUSTION CHAMBER THROUGH HEAD AREA a Check for intake valve seals to be damaged missing or loose Repair or replace as necessaary b Check for worn valve stems or guides Repair as necessary c Inspect for plugged oil drain back holes in head Correct as necessary d Inspect PCV system operation Correct as necessary EXCESSIVE OIL CONSUMPTION DUE TO OIL ENTERING COMBUSTION CHAMBER BY PASSING PISTON RINGS a Check engine oil level too high Correct as necessary b Check for excessive main or connecting rod bearing clearance and correct as necessary c Check for piston ring gaps not staggered and correct as necessary d Check for incorrect size rings installed and correct as necessary e Check for piston rings out of round broken or scored and replace as necessary f Inspect insufficient piston ring tension due to engine overheating and replace as necessary 8 Check for ring grooves or oil return slots clogged and corrected as necessary h Inspect rings sticking in ring grooves of piston and correct as necessary Inspect ring grooves worn excessively in piston and correct as necessary j Inspect compression rings installed upside down and correct as necessary k Check for excessively worn or scored cylinder walls and correct as necessary l Inspect oil too thin and repla
494. se and tie up away from work area 5 Disconnect front prop shaft from transfer case and tie up shaft away from work area 6 Disconnect shift lever rod from shift rail link On full time 4 wheel drive models disconnect shift levers at transfer case 7 Support transfer case and remove bolts attaching transfer case to transmission adapter 8 Move transfer case to rear until input shaft clears adapter and lower assembly from vehicle Installation 1 Support transfer case in suitable stand and position case 3 OR 4 SPEED TRANSMISSION WITH to transmission adapter Install bolts attaching case to MODEL 205 TRANSFER CASE adapter and torque to 45 ft Ibs 2 Remove stand as required and install bolts attaching transfer case to frame rail Bend lock tabs after assembly 3 Install connecting rod to shift rail link or connect shift levers to transfer case as applicable 4 Connect front prop shaft to transfer case front output shaft 5 Connect rear prop shaft to transfer case rear output shaft 6 Install crossmember support and skid plate if removed AUTOMATIC TRANSMISSION WITH MODEL 203 TRANSFER CASE 7 Connect speedometer cable back up lamp and TCS switch Fig 1Q Transfer Case Installation 8 Fill transfer case to proper level with lubricant specified in the lubricant section of the Truck Chassis Service Manual TRANSFER CASE REPLACEMENT Figs 10 20 9 Lower and remove vehicle from hoist Removal CAUTION Check and
495. se switch above Engagement Switch Test Check engagement switch and connecting wiring as follows Unplug engagement switch connector brown blue black at electrical wiring harness connector then perform the following tests fig 7C Test 1 Connect ohmmeter between terminal 1 brown wire and terminal 2 blue wire Continuity shall be maintained until switch is depressed all the way in Test 2 Connect ohmmeter between terminal 1 brown wire and terminaljt3 black wire No continuity shall be shown however when the button is partially depressed continuity shall be indicated When the button is pressed all the way down no continuity shall be shown Test3 3 Connect ohmmeter between terminal 2 blue wire and terminal 3 black wire Button released continuity however when the button is depressed partially and fully continuity shall be shown Harness Test see Fig 7C 1 Disconnect engage switch wire harness connector from the main harness connector red brown white and white wires 2 Connect ohmmeter between point C brown white stripe wire in main wire harness and ground Make sure the Regulator is well grounded to the chassis The ohmmeter should read between 42 and 49 ohms If a resistance either above or below the value indicated is shown then disconnect the connector from the Regulator and measure the resistance of the brown white stripe wire from point C to D It should measure 40 ohms 4 2 o
496. seat with needle installed 14 needle is defective replace with a factory matched set 2 Check float for being loaded with fuel bent float hanger or binds in the float arm NOTE Check float for fuel absorption by lightly squeezing between fingers If wetness appears on surface or float feels heavy check with known good float replace the float assembly 3 Check float adjustments as specified in carburetor over haul section 4 f excessive dirt is found in the carburetor clean the fuel system and carburetor Replace fuel filter as necessary TRUCK SUPP 5 6M 16 ENGINE FUEL Problem k POSSIBLE CAUSE Fuel Restriction Dirt or water in fuel system Fuel level Main metering jet defective loose or incorrect part Power system in carburetor not functioning properly Power valve sticking in down position Vacuum leakage Problem POOR FUEL ECONOMY Engine needs complete tune up Choke valve not fully opening Fuel leaks Power system in carburetor not functioning properly Power valve sticking in up position High fuel level in carburetor or carburetor flooding ENGINE RUNS UNEVEN OR SURGES CORRECTIVE ACTION Check all hoses and fuel lines for bends kinks or leaks Straighten and secure in position Check all fuel filters If plugged or dirty replace Clean fuel tank and lines Remove and clean carburetor Adjust float as specified in carburetor overhaul section Check for free float and
497. semblies pump plungers should not be immersed in carburetor cleaner 2 Blow out all passages in castings dry with compressed air and blow off all parts until they are dry CAUTION Do not pass drills or wires through calibrated jets or passages as they may enlarge orifices and seriously affect carburetor calibration 3 Check all parts for wear If wear is noted defective parts must be replaced Note especially the following a Check float needle and seat for wear If wear is noted the assembly must be replaced b Check float lip for wear and float for damage Repair or replace as necessary c Visually check throttle and choke shaft bores in throttle body and cover castings for wear and out of round Repair or replace as necessary d Inspect idle adjusting needles if removed for burrs or ridges or being bent Such a condition requires replacement TRUCK SUPP OVERHAUL 6 e Inspect fast idle cam If wear is noted on steps of cam it should be replaced as it may upset engine idle speed during the warm up period f Inspect the pump plunger cup and expander spring Replace plunger if cup or spring is damaged or distorted g Inspect power piston and spring for burrs or being bent Replace as necessary Check filters for dirt or lint Replace as necessary Inspect venturi cluster casting If any parts in casting are loose or damaged the cluster assembly must be replaced Use new gaskets in reassem
498. sembly and the shaft seal assembly provides a front head to shaft seal Refrigerant flows into the crankcase from the connector block at the rear is drawn through the reeds attached to the piston top during the suction stroke and is discharged outward through the discharge valve plate which is held in place at the top of the cylinder by a snap ring Discharge gas flows out of the compressor muffler cavity through the connector block at the rear TRUCK SUPP SERVICE pepo dx3 10 919 05 1eput 2 XIS Jeixy 614 3231 AH3S 44 5 WONHL O Ring Front Head Shaft Seal Assembly Switch Retainer Ring Seol Seat O Rings Seal Seat Retainer Ring Pressure Relief Valve Absorbent Sleeve Seal Retainer O Ring ue Coil Retainer Ring O Ring o a Compressor Shell Clutch Coil and Housing Assembly Suction Screen lt Inner Oil Pump Gear ss Plug Pulley Bearing Superheat RN Oil Pick up Tube pr O Ring Bearing Retainer ME e Pulley Retainer Ring Lock Nut 2 4 Clutch Plate and Rear Head f Hub Assembly p Outer Oil Pump Geor I s 28 Retainer Ring Rear Discharge Valve Plate B AN A Lock Nut Rear Suction Reed DNINOILIGNOO HIV ANY H31V3H ZV L Bushing Needle Beoring Mele aa O Ring gt _ Crossover Cover Rear Cylinder Half Teflon Piston Beet e n 0 Front Cylinder Holf Ball Needle Bearing Sho
499. sh with fill plug hole Add catalyst if required 7 Apply an anti seize compound to the fill plug install and tighten to 50 pound feet Bottom Cover If for any reason the bottom cover of the converter is torn or severely damaged it can be replaced with a repair kit Bottom Cover Replacement Remove bottom cover by cutting close to the bottom outside edge Figure 10 and 11 Do not remove the fill plug The depth of the cut must be very shallow to prevent damage to the inner shell of the converter Remove insulation Fig 12 Inspect inner shell of the converter for damage If there is damage in the inner shell the converter assembly must be replaced Fig 13 Place new insulation in the replacement cover Apply sealing compound all around the cover after the insulation is in position Apply extra sealer at the front and rear opening for the pipes Fig 14 Install replacement cover on converter Fig 14 Install cover retaining channels on both sides of the converter Fig 15 Attach 2 clamps over retaining channels at each end of the converter Fig 16 J 25077 1 Fig 7 Installing Vibrator TRUCK SUPP SERVICE FUEL TANK AND EXHAUST SYSTEM 8 5 FILL TUBE EXTENSION CATALYST CONTAINER Fig 9 Fill Tube Extension Fig 10 Removing Bottom Cover Fig 11 Removing Bottom Cover TRUCK SUPP SERVICE 8 6 FUEL TANK AND EXHAUST SYSTEM CATALYTIC CONVERTER
500. should be noted here that there is a supplementary fuel feed passage in the bottom of the float bowl adjacent to the main metering jet Fuel is picked up from the float bowl and passes through a calibrated hole past a calibration screw and on into the same fuel passage which leads from the main metering jet to the main fuel well The purpose of the adjustable fuel feed is to allow the factory to refine part throttle calibration to meet very accurate air fuel mixture ratios This adjustment 18 made using very sensitive Instrumentation and the screw should not be tampered with or it will require complete float bowl or unit replacement POWER ENRICHMENT SYSTEM Fig 5 The vacuum operated power enrichment system is used to slightly enrichen mixture ratios during moderate to heavy loads during acceleration The necessary enrichment is obtained by movement of a spring loaded vacuum piston which senses changes in manifold vacuum The amount of enrichment is controlled by the clearance between the groove in the power piston and the diameter of the power piston drive rod During part throttle and cruising ranges manifold vacuum is sufficient to hold the power piston down against spring tension The upper part of the groove in the power piston is held down against the top side of the drive rod This places the main metering rod lower in the jet for maximum economy On moderate to heavy accelerations manifold vacuum drops and the power piston spring
501. side Door Handle 45 in lb Seat Support to Floor Clamps 40 ft Ib Ib Ib TRUCK SUPP SPECS SPECIFICATIONS 4 FRONT SUSPENSION SECTION 3 WHEEL ALIGNMENT SPECIFICATIONS CASTER NODE DIMENSION IN INCHES MODELS 2 1 2 2 3 4 3 3 1 4 3 1 2 3 3 4 i 5 CIO 42 P41 101 2711 174 17 3 4 1 2 1745 0 1 27 347 ADJUSTMENT PROVISION 10 620 030 2 1 4 2 11 2 11 4 41 3 4 1 2 1 4 1 4 LM sso esie s oa sere orm oe og 5 3 4 5 1 2 5 5 4 1 2 4 1 4 4 4 3 1 2 3 1 4 3 HOME 32 CAMBER 41 47 1 1 2 NO ADJUSTMENT PROVISION 1 4 10 20 30 K10 K20 G10 G20 G30 Camber on P Truck is dependent on dimension A as explained on page 3 15 of the 1974 Light Duty Truck Service Manual After measuring dimension A set camber as follows svepsvr sse gt sve P10 0 1 4 41 2 1 4 1 4 1 4 0 0 0 P20 P30 0 1 4 1 42 1 4 1 4 1 4 1 4 0 0 ALIGNMENT TOLERANCES WARRANTY RESETTING PERIODIC REPAIR TARGET MOTOR CHECKING VEHICLE INSPECTION C10 C20 C30 K10 K20 10 620 630 P10 P20 P30 MOTORHOME P30 32 5 16 Refer to page 3 15 of the 1974 Light Duty Truck Service Manual TRUCK SUPP SPECS
502. sition automatic transmission in Drive with light duty emissions or Neutral with heavy duty emissions Position manual transmission in Neutral 8 Remove air cleaner and cut off tab on limiter cap Do not remove cap from screw Install air cleaner 9 Turn idle mixture screw clockwise leaner or counterclockwise richer until maximum idle speed is achieved 10 Set idle speed to higher specified rpm by turning solenoid in or out Example 575 550 11 Observe tachometer and turn idle mixture screw clockwise leaner until idle speed is at lower specified rpm Example 575 550 12 Shut off engine and remove tachometer 13 Connect all hoses to vapor canister 14 Connect vacuum advance hose if disconnected FAST IDLE ADJUSTMENT Fig 10 1 Check low and curb idle speed and adjust as required 3 SUPPORT LEVER WITH PLIERS BEND TANG IN OR OUT TO OBTAIN SPECIFIED FAST IDLER P M SEE INSET CLEARANCE SECOND HIGH NC 1JADJUST CURB IDLE M SPEEO WITH IDLE STOP Z PAAGE CAM FOLLOWER s SOLENOID ISEE DECAL TANG HIGH STEP OF CAM FAST IDLE CAM STEPS Fig 10 Fast Idle Adjustment 1MV 2 With engine at normal operating temperature air cleaner on choke open valve signal line disconnected and plugged and air conditioning OFF connect tachometer to engine 3 Disconnect vacuum advance hose at distributor and plug hose on an engine with ported spark vacuum advance 4 Start engine a
503. sitions 6 Connect check rod into lower choke lever inside bowl cavity they install choke rod into slot in upper choke lever and retain the choke lever to the end of the choke shaft with attaching screw Tighten securely Make sure that the flats on the end of the choke shaft align with flats in the choke lever The front and rear vacuum break units fast idle cam choke rod and inside thermostatic choke coil lever must be adjusted properly before installing the choke thermostatic coil and cover assembly and gasket Refer to the Adjustment Procedures in Service Section 7 After the vacuum break fast idle cam choke rod and inside thermostatic coil lever are adjusted the thermostatic coil and cover and gasket on hot air choke model should be installed and the cover assembly rotated until the choke valve just closes On all models except 454 V8 tang on thermostatic coil must be installed in slot in inside choke coil lever pick up arm On M4ME electric choke model coil tang contacts bottom side of inside choke coil lever pick up arm CAUTION M4ME electric choke model do not install a choke cover gasket between the electric choke assembly and the choke housing Align index point on cover with specified mark on housing as shown on adjustment chart Install three choke cover retainers and screws and tighten securely 8 If used position and retain throttle lever actuator TRUCK SUPP OVERHAUL 6M 20 C
504. sprays into the secondary bores supplementing the air fuel mixture delivered from the primary bores In this way correct air fuel mixtures through the secondary bores are controlled by the position of the metering rods in the orifice plates There are other features incorporated in the secondary metering system as follows 1 The main well bleed tubes extend below the fuel level in the main well These bleed air into the fuel in the well to quickly emulsify the fuel with air for good atomization as it leaves the secondary discharge nozzles 2 Two baffle plates are used one in each secondary bore They extend up and around the secondary fuel discharge nozzles Their purpose is to provide good fuel distribution at lower air flows by preventing too much fuel from going to the front of the engine As mentioned earlier a baffle is added on the underneath side of the air valve on some applications to aid in good mixture distribution from the secondary side of the carburetor AIR VALVE DASHPOT Fig 41 The air valve dashpot operates off of the front choke vacuum break diaphragm unit The secondary air valve is connected to the vacuum break unit by a rod to control the opening rate of the air valve This delays the air valve opening rate to prevent secondary discharge nozzle lag Whenever manifold vacuum is above approximately 5 to 6 Hg the vacuum break diaphragm is seated plunger is fully inward against spring tension At
505. ssary Check improper spark timing and correct as necessary i Check excessive idling and correct as necessary NOISY VALVES Check and adjust valve lash if necessary b Check for excessively worn dirty or faulty valve lifters Replace if necessary Check for worn valve guides Repair as necessary Check for excessive run out of valve seat or valve face Repair as necessary Check for worn camshaft lobes Replace camshaft if necessary f Inspect for pulled or loose rocker arm studs Repair or replace as necessary g Check for bent push rods Replace if necessary h Inspect for broken valve spring Replace if necessary TRUCK SUPP SERVICE B n idm l imum TT 6 10 ENGINE NOISY PISTONS AND RINGS a Check for excessive piston to bore clearance Correct as necessary b Inspect for improper fit of piston pin Correct as necessary c Inspect for excessive accumulation of carbon in combustion chamber or on piston tops Clean and or repair as necessary d Check for connecting rods alignment Correct as necessary e Inspect for excessive clearance between rings and grooves Repair or replace as necessary f Check for broken piston rings Replace as necessary BROKEN PISTONS AND OR RINGS a Check for undersize pistons Replace if necessary b Check for wrong type and or size rings installed Replace if necessary c Check
506. st into the bore Place the snap ring over a smooth round ended tool and depress the pistons in the bore Assemble the retaining ring in the groove in the cylinder bore Assemble the compensating valve seals and the small O ring seal in the recesses on the bottom of the reservoir Be sure that all seals are fully seated While holding the pistons depressed assemble the compensating valve springs and the compensating valve poppets in the compensating valve ports Holding the pistons compressed position the reservoir on the master cylinder body and secure with the four mounting bolts Tighten the bolts to 12 15 ft Ibs Bench Bleeding 1 Plug the outlet ports and fasten the master cylinder in a vise with the front end tilted slightly down 2 Fill the reservoir with clean brake fluid Use any tool with a smooth rounded end to depress and release the TRUCK SUPP SERVICE BRAKES 5 13 1 6 amp N41 350 V 8 amp N41 Fig 9 Power Steering Hose Routing Models TRUCK SUPP SERVICE 5 14 BRAKES L 6 amp N40 ring Hose Routing G Models Fig 10 Power Stee BRAKES 5 15 MOTOR HOME 2 o LU o o e L6 amp N40 Fig 11 Power Steering Hose Routing P Models TRUCK SUPP SERVICE 5 16 BRAKES primary piston several times Reposition the master cylinder in the vise with the front end tilted slightly
507. stems see chart Sustained heavy duty and high speed operation or operation under adverse conditions may require more frequent servicing For maintenance and lubrication information on trucks designated with heavy duty emission control systems continue to refer to Section O of the 1974 Light Duty Truck Shop Manual ENGINE Oil and Filter Recommendations The letter designation SE has been established to correspond with the requirements of GM 6136 M SE engine oils will be better quality and perform better than those identified with SA through SD designations and are recommended for all light duty gasoline trucks LIGHT AND HEAVY DUTY EMISSION CLASS VEHICLES Light Duty Vehicle C10 Pickup up to 6000 Ibs GVW G 10 Van Heavy Duty C10 Pickup over 6000 Ibs GVW C10 Suburban C 10 Blazer Jimmy C20 30 All models G 20 30 Van K models models regardless of model year and previous engine oil quality recommendations Oil Change Period e Use only SE engine oil e Change oil each 6 months or 7 500 miles If more than 7 500 miles are driven in a 6 month period change oil each 7 500 miles TRUCK SUPP SERVICE e Change oil each 3 months or 3 000 miles whichever occurs first under the following conditions Driving in dusty conditions Trailer pulling or camper use Frequent long runs at high speeds and high ambient temperatures Motor Home use Stop and go type service such as
508. step number 13 from removal procedure as found in 1974 Overhaul Manual SPEEDOMETER DRIVE GEAR Replacement If removal and installation or replacement of the speedometer drive gear is necessary proceed as follows Nylon Speedometer Drive Gear 1 Depress clip and slide speedometer drive gear off output shaft 2 To install place clip square end toward flange of shaft into hole in output shaft Align slot in speedometer drive gear with clip and install gear NOTE The nylon speedometer drive gear is installed at the factory only ALL service replacement speedometer drive gears are STEEL When replacing the nylon speedometer drive gear with a steel gear discard the retaining clip and refer to Step 2 of steel speedometer drive gear installation Steel Speedometer Drive Gear 1 Install speedometer drive gear remover Tool J 21427 01 and J 9539 bolts with J 8105 or suitable puller on output shaft and remove speedometer drive gear fig 5B 2 Install new steel speedometer drive gear and drive to location 5 43 64 below end of output shaft for all models except CA CG and CR 11 15 64 below end TRUCK SUPP OVERHAUL AUTOMATIC TRANSMISSION 7 5 GAGING STEPS LOCATED ON PIN THREE SIDES OF TOOL PART NO J 21370 9 IDENTIFICATION THIS STEP LONGEST PIN USE PIN NO 8627195 TOOL 21370 9 LOWER STEP SHORTEST PIN Note The Identification Rings are 030 and 100 wide TORQUE Fig 4B Checking Rear
509. ster should be replaced as an NOTE Using a screw extractor damages the seat in assembly the check valve A new charging valve kit must be installed whenever the check valve is removed from the accumulator valve bore NOTE The clearance between the valve spool and the spool bore of the housing assembly is important Because of this the valve spool and the housing 16 Use a 1 4 or a 5 16 spiral flute type screw extractor assembly make up a selective assembly the valve spool to remove the tube seats from the booster ports is selected to match the spool bore TRUCK SUPP OVERHAUL 5 4 BRAKES Fig 5 Removing Booster Pedal Rod Typical 4 Inspect the input rod and piston assembly for corrosion nicks scoring or excessive wear If the piston is damaged the input rod and piston assembly should be replaced Inspect the piston bore in the booster housing for corrosion nicks scoring or other damage If the bore is damaged the entire booster must be replaced as an assembly Assembly CAUTION 5Be sure to keep parts clean until reassembly Re wash at reassembly if there is any occasion to doubt cleanliness such as parts dropped or left exposed for eight hours or longer Lubricate all seals and metal friction points with power steering fluid INPUT ROD AND J 24553 SEALS Lips of Seals Toward Open End of Tool Fig 6 Installing Input Rod Seals J 24551 INPUT ROD AND PISTON Fig 7 Inst
510. stment TRUCK SUPP OVERHAUL HOLD POWER PISTON DOWN 3 Bend float pontoon up or down at float arm junction to adjust Metering Rod Adjustment Fig 8 Open throttle valve slide metering rod out of holder and remove from main metering jet To check adjustment back out idle stop solenoid and rotate fast idle cam so that fast idle cam follower is not contacting steps on cam With throttle valve completely closed apply pressure to top of power piston and hold piston down against its stop Holding downward pressure on power piston swing metering rod holder over flat surface of bowl casting next to carburetor bore Insert gauge between bowl casting and lower surface of metering rod holder Gauge should have a slide fit between both surfaces as shown 79 A BEND HERE BENDING TOOL FLOAT BOWL SURFACE GASKET REMOVED O BACK OUT IDLE SPEED SCREW HOLD THROTTLE VALVE COMPLETELY CLOSED Fig 8 Metering Rod Adjustment CARBURETOR 6 5 To adjust carefully bend metering rod holder up or down After adjustment install metering rod and spring assembly Install rod in jet then install in hanger Install air horn gasket on float bowl by carefully sliding slit portion of gasket over metering rod holder Then align gasket with dowels provided on top of bowl casting and press gasket firmly in place Air Horn 1 Install choke shaft assembly and choke valve into air horn if rem
511. sufficiently charged for testing ENGINE ELECTRICAL 6Y 7 DARKENED INDICATOR WITH GREEN DOT FULLY CHARGED DARKENED INDICATOR NO GREEN DOT NEEDS CHARGING LIGHTENED INDICATOR REPLACE BATTERY Fig 2b Battery Charge Indicator Charge Indicator Dark Green Dot Not Visible Fig 2b If the charge indicator is dark and the green dot is not visible charge battery until dot appears but not more than 60 ampere hours for example 15 amperes for four hours NOTE Some chargers are constant current chargers while others are constant voltage chargers If a constant voltage charger is used for charging the battery and the green dot fails to appear after prolonged charging it may be necessary to tip the battery slightly from side to side a few times for the green dot to appear Charge Indicator Light Fig 2b If the charge indicator is light replace battery DO NOT attempt to charge or jump when charge indicator is light NOTE A battery that failed prematurely and exhibited a light charge indicator condition may indicate a need for checking the charging system of the vehicle Remove Surface Charge Connect a 300 ampere load across battery terminals for 15 seconds to remove surface charge from battery Load Test 1 Connect voltmeter and an ampere load across battery terminals as indicated below BATTERY AMPS FOR TYPE LOAD TEST 170 130 210 TRUCK SUPP SERVICE O
512. suspension steering linkage and constant velocity universal joint Also lubricate transmission shift linkage hood latch hood hinges and parking brake cable guides and linkage clutch linkage propellor shaft slip joint universal joints and brake and clutch pedal springs Lubricate suspension and steering linkage every 3 months or 3 000 miles when operating under dusty or muddy conditions and in extensive off road use A 2 FLUID LEVELS Check level of fluid in brake master cylinder power steering pump battery engine axle transmission and windshield washer Engine coolant should be checked for proper level and freeze protection to at least 20 29 F to the lowest temperature expected during the period of vehicle operation Proper engine coolant also provides corrosion protection Any significant fluid loss in any of these systems or units could mean that a malfunction is developing and corrective action should be taken immediately On some models a low fluid level in the brake master cylinder front reservoir could also be an indicator that the disc brake pads need replacing Also a Safety Service Also an Emission Control Service EEE TOL JC Mv ERE GENERAL INFORMATION AND LUBRICATION 0 13 A 3 ENGINE OIL Change each 6 months or 7 500 miles whichever occurs first under normal driving conditions or each 3 mont
513. t 4 Remove two screws holding module to housing and move module to a position where electrical connector may be removed from B and C terminals of module 5 Use needle nose pliers or similar tool to remove pole piece and plate assembly electrical leads from W White and G Green terminals of module Do not remove leads by pulling on the wires as damage to the leads may occur 6 Install replacement module in reverse order of removal During installation make sure a liberal amount of special silicone grease is applied to the metal mounting surface of module to insure proper cooling 7 Check operation of new module by starting and running vehicle Pole Piece and Plate Assembly Replacement Figs 7i 9i The pole piece and plate assembly is serviced by complete replacement only The three screws securing stationary pole piece and permanent magnet should not be disturbed except under extreme conditions since the pole piece is adjusted by the factory to critical dimensions During replacement make sure the replacement pole piece and plate assembly is the correct specified part One quick method of assuring a correct part is to observe the retainer bow that holds the white and green electrical leads together is color coded yellow The correct pole piece and plate assembly for all 6 and 8 cylinder engines are color coded yellow 1 Remove distributor as described previously in this section 2 Support distributor gear on a bloc
514. t failures in any way the location of the various unit numbers have been indicated These unit numbers and their prefix or suffix are necessary on these papers for various reasons such as accounting follow up on production etc The prefixes on certain units identify the plant in which the unit was manufactured and thereby permits proper follow up of the plant involved to get corrections made when necessary Always include the prefix in the number Axles Series 10 20 and P30 Code is stamped on Front of Right Rear Axle Tube e Series C G30 except dual wheel code is stamped at the Forward Upper Surface of Carrier e Dual Wheel Part Number and Production Code is stamped on Front of Right Axle Tube Transmissions e 3 Speed Transmission Unit Number Located on Lower Left Side of Case Adjacent to Rear of Cover 4 Speed Transmission Unit Number Stamped on Rear of Case Above Output e Turbo Hydra Matic 350 Transmission Unit Number Located on Right Rear Vertical Surface of Oil Pan TRUCK SUPP SERVICE 0 2 GENERAL INFORMATION AND LUBRICATION TRUCK MODEL IDENTIFICATION Chassis Type GVW Range Cab or Body Style Body Ordering Code Chassis Type C Conventional 4 x 2 G Forward Control 4 x 2 Body Frame Integral K Conventional 4 x 4 Four Wheel Drive P Forward Control 4 x 2 Conventional Series GVW Range 1 4800 to 7300 2 6400 to 8400 3 6400 to 14 000 Cab or Body Style 03 Co
515. t race Fig 44 If the pull is just less than 4 ounces add 0005 to the thickness of the feeler stock used to measure the clearance If the pull on the scale reads just over 8 ounces then subtract 0005 from the thickness of the feeler stock Select a race TWO 2 FULL SIZES LARGER than feeler gage thickness If feeler gage is 007 select a No 9 or 090 race Select a thrust race with a number corresponding to TWO 2 FULL SIZES LARGER than Dial Indicator or feeler gage measurement of the amount of end play shown If measurement is 007 select a No 9 TRUCK SUPP OVERHAUL AIR CONDITIONING COMPRESSOR 1 17 THRUST BEARING RACE PART NO IDENTIFICATION DIAL INDICATOR ENDING IN STAMP READING PART NO IDENTIFICATION MIN FEELER ENDING IN STAMP GAGE READING SELECT AND USE SHOE NO POSITION POSITION POSITION 1 2 3 PISTON NO 1 019 0195 019 PISTON 2 020 020 020 PISTON NO 3 021 021 022 Fig 42 Selection of Proper A 6 Shoe Disc CHECKING FOR SHAFT END PLAY PISTON PLAY THRUST RACE SHOE DISC Clamp J 8001 1 Sleeve J 8001 2 Fig 44 Checking Piston and Shaft End Play field service Thrust races are identified on the part by their thickness in thousandths in excess of the thickness of the ZERO thrust race Bearing 2 This number also corresponds to the last three digits x of the piece part number See Thrust Race siz
516. t area for any lint dirt or foreign material and be sure these areas are perfectly clean before installing new seal parts Be sure seal AIR CONDITIONING COMPRESSOR 1 29 J 9480 2 AIR GAP 020 040 Fig 73 Installing Clutch Plate and Hub Assembly 1 23128 CERAMIC SEAL SEAT J 22974 Fig 74 Removing Seal Seat remover and installer J 9392 seal protector J 22974 and O ring installer J 21508 are clean internally and externally The seal seat O ring shaft seal and seal seat should be dipped in clean 525 Viscosity oil and not handled any more than is absolutely necessary by hand particularly the mating surfaces Any dirt or lint on sealing surfaces could cause seal leak or seal damage 1 Dip new seal seat O ring in clean 525 Viscosity oil and assemble onto O ring installer J 21508 Fig 76 2 Insert O ring installer J 21508 into the compressor neck until the tool bottoms Lower the movable slide of O ring installer to release O ring into seal seat TRUCK SUPP OVERHAUL 1 30 AIR CONDITIONING COMPRESSOR shaft Slowly turn the tool clockwise while applying light pressure until seal engages the flats of compressor shaft and can be seated into place Rotate tool J 9392 counterclockwise to disengage from seal tabs and remove tool 5 Attach ceramic seal seat to the seal seat remover and installer J 23128 and dip ceramic seat in clean 525 viscosity oil to coat seal face and ou
517. t throttle allows each carburetor to be individually calibrated at time of assembly Each carburetor is adjusted by the manufacturer to provide the most ideal air fuel ratio for low exhaust emissions The adjustable part throttle screw is used to raise or lower the power piston and metering rods to provide this ratio In part throttle and cruising ranges manifold vacuum is sufficient to hold the power piston down against spring tension so that the larger diameter of the metering rod is held in the main metering jet orifice Mixture enrichment is not necessary at this point However as engine load is increased to a point where extra fuel enrichment is required the spring tension overcomes the vacuum pull on the power piston and the tapered primary metering rod moves upward in the main metering jet orifice The smaller diameter of the metering rod allows more fuel to pass through the main metering jet and enrich the mixture flowing into the primary main wells and out the main discharge nozzles When manifold vacuum rises and mixture enrichment is no longer needed the vacuum overcomes the power piston spring tension and returns the larger portion of the metering rod into the metering jet orifice and back to normal economy ranges As the engine speed increases the primary side of the carburetor can no longer meet the engine air and fuel requirements To meet these demands the secondary side of the carburetor is used As the secondary th
518. te pipe ends to A cable to be routed rest against steering Ye above power housing steering pipes and NC clearance Clamp must be installed with bolt head toward front of vehicle Hose assembly must be installed against steering gear cover 305 350 400 V 8 G 10 30 Hose assembly 4 must be located against hydra boost mounting bracket _ 10 TO 15 VIEW A 305 350 400 v8 CK 10 30 ABOOST EXCEPT HYDRABO MOTOR HOME Fig 20 Power Steering Hose Routing Fig 23 Power Steering Hose Routing TRUCK SUPP SERVICE 9 10 STEERING Route Pipe Assembly Inlet parallel to of steering gear EXCEPT HYDRABOOST Fig 24 Power Steering Hose Routing 4 nt VIEW A be installed against steering gear cover Route pipe assembly 15 to parallel of steering gear assembly must be installed against steering gear cover 7 454 V 8 C 30 W HYDRABOOST AND 4 56 AXLE Fig 26 Power Steering Hose Routing 454 8 C 20 30 W VACUUM POWER BRAKES AND 4 56 AXLE Route pipe assembly inlet outboard 15 to parallel of steering gear 7 NE located against hydraboost mounting bracket ly must be 454 V 8 MOTOR HOME 199 203 Diameter hole in radiator support 454 V 8 C 20 30 FLUID COOLER ASSEMBLY Fig 29 Fluid Cooler Line Routing TRUCK SUPP SERVICE STEERING
519. ter so end is below liquid level and watch for bubbles Presence of bubbles indicates a leaking radiator cap Replace cap if necessary If leaking is still indicated by moving handle of Hose Gauge J 23636 and visible external leaks have been TRUCK SUPP SERVICE 6K 2 ENGINE eliminated then the leak must be internal and more complicated testing must be performed to determine which part must be repaired or replaced Such internal leaks will be corrected by doing the following in this order a Torque the head bolts b Replace head gaskets Replace heads Replace engine block RADIATOR REPLACEMENT All Except P30 32 Chassis Refer to Figure 1 through 4 for radiator assembly positions for C K G and P30 42 Series vehicles MOUNTING PANEL LPP PIII wl Fifi 66077 Lui L6 ENGINE amp MANUAL TRANSMISSION Fig 1 Radiator Mounting P20 42 MOUNTING PANEL erum 16 SHOWN TER a gt Me lt PAD 21 CLIP amp RADIATOR SUPPORT gt z lt Fig 2 Radiator and Fan Shroud CK P30 42 r m IE r Removal 1 Remove radiator cap when engine is cool by e Slowly rotate cap counter clockwise to detent do not press down while rotating Wait until any residual pressure indicated by a hissing sound is relieved After hissing ceases press down on cap while continuing to rotate counterclockwise CAUTION avoid the d
520. ter surface Carefully install seat over compressor shaft and seal protector J 22974 and push seat into place with a rotary motion Remove tools J 23128 and J 22974 6 Install new seal seat retainer ring with snap ring pliers J 5403 7 Leak test compressor as described under Leak Testing the Compressor and correct any leaks found SHAFT SEAL J 22974 8 Reinstall clutch plate and hub assembly as described under Compressor Clutch Plate and Hub Assembly COMPRESSOR CLUTCH ROTOR amp BEARING Compressor Clutch Rotor amp Bearing 1 Remove the clutch plate and hub assembly as described Fig 75 Removing Shaft Seal under Compressor Clutch Plate and Hub Assembly 2 Remove rotor and bearing assembly retaining ring using snap ring pliers J 6083 Fig 77 Mark the location of clutch coil terminals If clutch rotor and or rotor bearing only are to be replaced bend the lockwashers away from pulley rim mounting screws Fig 78 and remove the six mounting screws and special lockwashers before proceeding with Step 3 Discard special lockwashers 3 Install rotor and bearing puller guide J 25031 1 over the 21508 end of compressor shaft and seat on the front head of compressor Fig 78 SEAN SRAN SEANSS 4 Install rotor and bearing puller J 25031 2 down into rotor until the puller arms engage the recessed edge of rotor hub Hold puller and arms in place and tighten puller screw against puller guide to remove clutch
521. the booster The tab on the inside diameter of the large hole in the bracket should fit into a slot in the threaded portion of the booster hub 14 Install the NEW bracket nut with the staking groove outward on the threaded hub of the booster Using Tool 16 17 18 BRAKES 5 5 SLOT IN BOOSTER HUB Fig 9 Staking Mounting Bracket Nut Typical J 24554 and a torque wrench fig 8 tighten the nut to 95 120 ft Ibs CAUTION See Caution on Page 1 of this section Use a hammer and a small punch inserted into the staking groove of the nut at the slot in the booster hub fig 9 to stake the nut in place Be sure that the outer thread of the nut is upset Assemble a NEW boot if used on the pedal rod Then assemble a NEW grommet in the groove near the end of the pedal rod Moisten the grommet with water to ease assembly and insert the grommet end of the pedal rod into the input rod end of the booster housing Push on the end of the pedal rod to seat the grommet in the groove inside the housing NOTE When the grommet 1 fully seated the pedal rod will rotate freely with no binding Slide the boot on the pedal rod and assemble the large end of the boot onto the hub of the power section TRUCK SUPP OVERHAUL 5 6 BRAKES omoouoggsomwmc J 4880 J 25085 J 21183 J 21524 J 21601 J 22657 J 22647 J 22677 J 22733 J 22805 SPECIAL TOOLS Snap Ring Pliers Special Socket Height Gauge
522. the large end of the tool into the piston fig 7 and slide the tool and piston into the piston bore and through the piston seal Assemble the NEW O ring onto the NEW accumulator check valve and dip the assembly in clean power steering fluid Insert the check valve into the accumulator valve recess in the housing flange Assemble the new ball and spacer in the same recess TRUCK SUPP OVERHAUL Fig 8 Installing Mounting Bracket Nut Typical 9 Assemble the NEW O ring onto the charging valve plunger seat and insert the plunger into the seat Dip the assembly in clean power steering fluid and insert it into the charging valve recess 10 Dip the spool assembly in clean power steering fluid and insert the assembly into the spool bore in the housing Be sure that the pivot pins on the upper end of the input rod lever assembly are engaged in the groove in the sleeve Remove Tool J 24551 from the piston assembly 11 Position a NEW housing seal in the groove in the housing cover Then join the booster housing and cover and secure with five screws Tighten the screws to 18 26 ft lbs using Special Socket J 25085 CAUTION See Caution on Page 1 of this section 12 Assemble a NEW O ring seal on the spool plug Insert the spool spring and the spool plug in the forward end of the spool bore Press in on plug and assemble the plug snap ring in the groove in the bore 13 Position the mounting bracket on
523. the nipple on the vacuum break unit and apply suction by mouth or use tool J 23418 to apply vacuum Plunger should move inward and hold vacuum If not replace the unit NOTE Always check the fast idle cam adjustment before adjusting vacuum break unit Adjust choke coil rod 1 Clean and align choke valve and linkage necessary Replace if 2 Re adjust if part replacement is necessary Adjust low and curb idle speeds to specifications on label in engine compartment 1 Check fuel pump pressure and volume 2 Check for partially plugged fuel inlet filter Replace if dirty 3 Remove air horn and check float adjustments as specified in carburetor overhaul section gt Check float needle and seat for proper seal If a needle and seat tester is not available mouth suction can be applied to the needle seat with needle installed If needle is defective replace with a factory matched set 2 Check float for being loaded with fuel bent float hanger or binds in the float arm NOTE Check float for fuel absorption by lightly squeezing between fingers If wetness appears on surface or float feels heavy check with known good float replace the float assembly 3 Check float adjustments as specified in carburetor over haul section 4 excessive dirt is found in the carburetor clean the fuel system and carburetor Replace fuel filter as necessary TRUCK SUPP SERVICE DO r r Jn LLACLAAGA
524. the throttle valves so that they can be nearly closed at idle This reduces the amount of air flowing through the carburetor venturi to prevent the main fuel nozzles from feeding during idle operation Off Idle Operation As the primary throttle valves are opened from curb idle to increase engine speed additional fuel is needed to combine with the extra air entering the engine This is accomplished by the slotted off idle discharge ports As the primary throttle valves open they pass by the idle ports gradually exposing them to high engine vacuum below the throttle valves The additional fuel added from the off idle ports mixes with the increasing air flow past the opening throttle valves to meet increased engine air and fuel demands Further opening of the throttle valves increases the air velocity through the carburetor venturi sufficiently to cause low pressure at the lower idle air bleeds As a result fuel begins to discharge from the lower idle air bleed holes located at the bottom of the large venturi skirt and continues to do so throughout operation of the part throttle to wide open throttle ranges supplementing the main discharge nozzle delivery Canister Purge On California vehicles the fuel tank is not vented to atmosphere and all fuel vapors are collected in a vapor collection canister from the fuel tank vent In order to remove the fuel vapors collected in the vapor canister it is necessary to provide a means of
525. this point the vacuum break rod is in the forward end of the slot in the air valve lever and the air valves are closed During acceleration or heavy engine loads when the secondary throttle valves are open the manifold vacuum drops The spring located in the vacuum break diaphragm overcomes the vacuum pull and forces the plunger and link outward which in turn allows the air valves to open The opening rate of the air valves is controlled by the calibrated TRUCK SUPP SERVICE ACTUATING ROD AIR VALVE SHAFT LEVER FRONT VACUUM BREAK DIAPHRAGM Fig 41 Air Valve Dashpot restriction in the vacuum inlet nipple in the diaphragm cover This gives the dashpot action required to delay air valve opening enough for efficient fuel flow from the secondary discharge nozzles ACCELERATING PUMP SYSTEM Fig 42 During quick acceleration when the throttle is opened rapidly the air flow and manifold vacuum change almost instantaneously The fuel which is heavier tends to lag behind causing a momentary leanness The accelerator pump is used to provide the extra fuel necessary for smooth operation during this time The accelerating pump system consists of a spring loaded pump plunger and pump return spring operating in a fuel well The pump plunger is operated by a pump lever on the air horn which is connected directly to the throttle lever by a pump rod When the pump plunger moves upward in the pump well as happens during throttle
526. thods of phasing are used models with 32 splines use an alignment key as shown in figure 11 to obtain proper phasing The shafts can mate only in the correct position C and G models with 16 splines must be phased as shown in figure 12 The rear shaft must be rotated four splines 90 toward the left side of the vehicle after aligning the trunnions vertically as shown K models with 16 splines must align the trunnions vertically before installing Do not rotate the shafts VERTICAL FRONT YOKE OF REAR PROP SHAFT IN VERTICAL POSITIO PLACE TRANSMISSION SLEEVE YOKE IN VERTICAL POSITION VERTICAL REAR PROP SHAFT ROTATE REAR SHAFT 4 SPLINES 90 TOWARD L H SIDE INSTALL REAR SHAFT TO FRONT SHAFT Fig 12 Alignment for Phasing C and G Models Only TRUCK SUPP SERVICE Fig 13 Removing Lock Screw AXLE SHAFT Remove and Reinstall Axles equipped with 8 7 8 ring gears and Eaton Locking differentials use a thrust block on the pinion shaft which affects the removal of axle shafts as noted below 1 Raise the vehicle on a hoist Remove both rear wheel and tire assemblies and both rear brake drums 2 Remove the rear cover and drain the lubricant 3 Rotate the case to the position shown in figure 13 Support the pinion shaft so that it cannot fall into the case then remove the lock screw 4 Carefully withdraw the pinion shaft part way out as shown in figure 14 Rotate the case unti
527. tifying Front End of A 6 Piston Carefully remove the rear half of the cylinder from the pistons and set the front cylinder half with the piston shaft and axial plate in Compressing Fixture J 9397 Pull up on compressor shaft and remove piston previously identified as No 1 with balls and shoe discs from axial plate a Inspect the Teflon piston rings for nicks cuts or metal particles imbedded in exposed ring surface and replace the piston rings as required if either condition exists See Teflon Piston Ring Replacement procedure 6 Remove and discard the piston shoe discs 10 Remove and examine piston balls and if satisfactory for re use place balls in No 1 compartment of Parts Tray J 9402 Fig 33 Place piston in No 1 compartment of Parts Tray J 9402 with notch in casting web at front end of piston Fig 32 into the dimpled groove of Parts Tray compartment Repeat Steps 5 through 9 for Pistons No 2 and No 3 Remove rear combination of thrust races and thrust bearing from shaft Discard races and bearing TRUCK SUPP OVERHAUL 1 14 AIR CONDITIONING COMPRESSOR Fig 33 6 Parts Tray Thrust Races BLOCK J 21352 Fig 34 Removing Front Thrust Races and Bearings Remove shaft assembly from front cylinder half If the discharge cross over tube remained in the front cylinder half it may be necessary to bend discharge cross over tube slightly in order to remove shaft Remove
528. ting External and Internal 1 24 Major Repair Procedures 1 8 For Compressor REMOVAL AND INSTALLATION see 1974 Service Manual page 1A 58 For all practical purposes all V8 engine equipped vehicles make use of the same air conditioning 6 cylinder compressor Actual differences between compressors are found in their mounting brackets pulleys connector assemblies and compressor capacities none of which will affect the following Overhaul Procedures MINOR REPAIR PROCEDURES The following operations to the Compressor Clutch Plate and Hub Pulley and Bearing and Coil Housing are covered as Minor because they may be performed WITHOUT FIRST PURGING THE SYSTEM OR REMOVING THE COMPRESSOR from the vehicle The Compressor Shaft Seal assembly and Pressure Relief Valve may also be serviced WITHOUT REMOVING THE COMPRESSOR from the vehicle but these operations are covered later in this section as Major Repair Procedures because the system MUST FIRST BE PURGED of Refrigerant Illustrations used in describing these operations show the compressor removed from the vehicle only to more clearly illustrate the various operations When servicing the compressor remove only the necessary components that preliminary diagnosis indicates are in need of service Refer to Fig 1 and Fig 2 for information relative to parts nomenclature and location Removal installation o
529. to cool to room temperature before attempting to remove AIR CONDITIONING COMPRESSOR 1 35 33 1 24895 Wo MAIN BEARING Fig 90 Installing Main Bearing SHELL RETAINING STRAP Fig 9 1 Releasing Retaining Strap compressor shell as greater force will be required to remove the compressor shell when hot due to metal expansion difference between the aluminum cylinder and steel compressor shell 1 Pry shell retaining strap away from cylinder and position the strap high enough to clear cylinder as shell is removed Fig 91 2 Remove compressor holding fixture J 25008 1 and reverse holding fixture step block protrusions engaging compressor shell Install medium length bolts through holding fixture and thread them into compressor cylinder until the step of the fixture protrusions contact TRUCK SUPP OVERHAUL 1 36 AIR CONDITIONING COMPRESSOR Fig 92 Removing Shell Assembly Fig 93 Removing Valve Plate compressor shell finger tight both sides Fig 92 Check to be sure the step protrusions do not overlap the cylinder but will pass both sides 3 Using a wrench alternately tighten each approximately 1 4 turn to push shell free of O rings on cylinder If one screw appears to require more force to turn than the other immediately turn the other screw to bring the screw threading sequence in step or the shell will be cocked and made more difficult to remove Normal removal does not requ
530. ton No 1 and rear ball pocket position Shoe discs are provided in 0005 one half thousandths variations There are a total of 11 sizes available for field servicing All shoe discs are marked with the shoe size 20 21 SPRING SCALE Fig 40 Gaging Rear Piston Ball which corresponds to the last three digits of the piece part number See Shoe Disc size Chart in Fig 41 above Once a proper selection of the shoe has been made THE MATCHED COMBINATION OF SHOE DISC TO REAR BALL AND SPHERICAL CAVITY IN PISTON MUST BE KEPT IN PROPER RELATIONSHIP during disassembly after gaging operation and during final assembly of internal mechanism Repeat in detail the same gaging procedure outlined in Steps 15 through 18 for Piston No 2 and No 3 Mount Dial Indicator J 8001 3 on edge of Compressing Fixture J 9397 with Clamp J 8001 1 and Sleeve J 8001 2 Fig 43 Position Dial Indicator on rear end of shaft and adjust to zero Apply full hand force at end of mainshaft a few times before reading clearance This will help squeeze the oil out from between mating parts Push upward and record measurement Dial Indicator increments are 001 therefore reading must be estimated to nearest 0005 An alternate method of selecting a proper race is to use Gage Set J 9661 01 selecting a suitable feeler gage leaf until the result is a 4 to 8 ounce pull on the scale between the rear thrust bearing and upper or outer rear thrus
531. ts Fig 4 and is belt driven by the engine when the electromagnetic clutch assembly on the compressor is energized by the air conditioning controls The purpose of the compressor is to pump low pressure low temperature refrigerant vapor produced by the evaporator and compress it into a high pressure high temperature vapor which can then be readily condensed back to a liquid state by the condenser The compressor has a displacement of 10 0 cu in The compressor has variations in the pulley rim diameter specified for the respective vehicle applications The basic compressor mechanism is a modified scotch yoke with four cylinders located radially in the same plane Opposed pistons are pressed into a yoke which rides upon a slider block located on the shaft eccentric Rotation of the shaft provides reciprocating piston motion with no connecting rods The mechanism is completely balanced with counterweights Needle bearings are used for tbe shaft journals and the shaft eccentric Pistons and yokes along with the main cylinder housing and front cover are made from aluminum to provide light weight Teflon piston rings are used to provide both a gas compression seal and a piston to bore bearing surface The outer shell is a simple steel band which encloses a large annular discharge muffler space Two O rings provide a seal between the compressor shell and the compressor cylinder rubber seal ring seals the front head to the cylinder as
532. ts function of filtering air drawn into the engine through the carburetor the air cleaner also acts as a flame arrestor in the event the engine backfires Because backfiring may cause fire in the engine compartment the air cleanershould be installed atall times unlessiits removal is necessary for repair or maintenance services 5 Replace filter element located in carburetor inlet as indicated in Section 0 of this Manual TRUCK SUPP SPECS SPECIFICATIONS 12 ENGINE TORQUES In Line Small V 8 262 amp 350 Mark IV V 8 Camshaft Thrust Plate Crankcase Front Cover Flywheel Housing C Oil Filler Bypass Valve Oil Pan To Crankcase 80 lb in Oil Pan To Front Cover i Oil Pump Cover Rocker Arm Cover Camshaft Sprocket Clutch Pressure Plate _ _ 20 1 20 Ib ft Oil Pan To Crankcase 75 lb in 65 lb in Oil Pump 115 lb in Push Rod Cover 50 lb in Water Pump 15 lb in Clutch Pressure Plate Distributor Clamp 20 lb ft Flywheel Housing 30 Ib ft Manifold Exhaust 30 Ib f 20 lb ft D Manifold Exhaust to Inlet 30 Ib ft Manifold Inlet 30 Ib ft Manifold to head 35 Ib fi ft Thermostat Housing 30 lb ft Water Outlet Water Pump 3 8 24 Connecting Rod Cap 30 Ib ft 30
533. type clamp may be installed on the input shaft at this time to prevent loosing bearings when removing input shaft assembly from the range box Raise shift rail and drive out pin retaining shift fork to rail Remove shift rail poppet ball plug gasket spring and ball from case small magnet may be used to remove ball from case Push shift rail down lift up on lockout clutch and remove shift fork from clutch assembly Remove bolts retaining front ouput shaft rear bearing retainer to transfer case Tap on front of shaft or carefully pry retainer away from case Remove retainer from shaft and discard gasket Recover any roller bearings which may fall from rear cover TRUCK SUPP OVERHAUL 7M 16 MANUAL TRANSMISSION 1 2 3 4 5 6 7 8 9 4 5 P Adapter Input Drive Gear Pilot Brgs Range Selector Sliding Clutch Range Selector Housing Low Speed Gear Bushing Low Speed Gear Thrust Washer amp Locating Pin Gasket Input Brg Retainer Input Brg Brg Outer Ring Brg Retaining Ring Thrust Washer Locating Pin Lubricating Washer amp Spacer Intermediate Chain Housing Drive Shaft Sprocket Gasket Sliding Lock Clutch Rear Output Housing Rear Output Front Brg Vent Oil Seal 6 7 B 910 F 11 12 13 14 15 16 17 j 7 Oil Pump Speedometer Drive Gear Brg Retainer Ring Rear Output Rear Brg Rear Output Shaft Washer Locknut Rubber Spline Seal
534. ualizer adjusting nut until a moderate drag is felt when the rear wheels are rotated forward CAUTION See Caution on page 1 of this section 5 Fully release the parking brake and rotate the rear wheels No drag should be present BRAKE PEDAL POSITION WHEN ELECTRICAL CONTACT IS MADE BRAKE PEDAL IN NORMAL POSITION 1 00 to 1 24 Fig 2 Stoplamp Switch C K Models TRUCK SUPP SERVICE 5 6 BRAKES P Se ae MODELS Fig 3 Parking Brake Assembly Typical 6 Remove vehicle from hoist Adjustment Orsheln Type Refer to the 1974 Light Duty Truck Service Manual page 5 23 Adjustment Propshaft Internal Expanding Drum On 1 Jack up at least one rear wheel Block wheels and release hand brake 2 Remove cotter pin and clevis pin connecting pull rod and relay lever This will assure freedom for full shoe release CAUTION Jt may be necessary to knock out lanced area in brake drum with punch and hammer to gain entry into adjusting screw through brake drum Be sure all metal has been removed from parking brake compartment 3 Rotate brake drum to bring one of access holes into line with adjusting screw at bottom of shoes manual transmission top of shoes automatic transmission 4 Expand shoes by rotating adjusting screws with screwdriver inserted through hole in drum Move outer end of screwdriver away from drive shaft Continue adjustment until shoes are tight against drum and drum cannot
535. uld pull in Clamp off engine vacuum supply line and check for leakage The cruise release brake valve vacuum and connecting hoses can likewise be checked using a vacuum pump oneumneug 01129 3 24 B14 32IAH3S 490 32n81 ENGAGEMENT SWITCH SHOWN IN REST POSITION CRUISE RELEASE VALVE CRUISE RELEASE BRAKE LIGHT SWITCH BROWN WHITE BRAKE PEDAL RESISTANCE WIRE TO BRAKE LIGHT CIRCUIT 40 1 RED ENGAGEMENT SWITCH POSITIONS REST POSITION SPEED REGULATOR IGNITION SWITCH 00 07 oe DIRECTION OF ROTATION WITH SPEED INCREASE BOWDEN CABLE TO CLUTCH SPRING CARBURETOR LINKAGE 7 POSITION VARIABLE ORIFICE AIR CONTROL VALVE SWITCH N O BELOW 35 POWER UNIT CORE SHOWN IN N DE ENERGIZED POSITION TO MANIFOLO VACUUM M J 12 VOLTS DC AIR FILTER S3IHOSS322V 8 91 ACCESSORIES 15 9 CRUISE MASTER TROUBLESHOOTING MH i A A CHECK I FOR SYSTEMS WITH ERRATIC CRUISE PERFORMANCE CHECK FOR INOPERATIVE SYSTEMS MAKE ALL TESTS WITH TRANSMISSION SELECTOR IN PARK amp PARKING BRAKE ON EXCEPT WHERE INDICATED OTHERWISE RECONNECT ANY DISCONNECTED HOSES AND OR ELECTRICAL CONNECTORS IN PROPER MANNER AT THE COMPLETION OF TEST CHECK I CHECK SERVO CABLE ADJUSTMENT MUST HAVE MINIMUM AMOUNT OF LOST MOTION SEE SERVICE ADJUSTMENT PROCEDURE FIG 4 CHECK FOR PINCHED KINKED PLUGGED
536. ulley 5 Tension belt as outlined under Pump Belt Tension Adjustment 6 Bleed as outlined under Bleeding Power Steering System POWER STEERING HOSES When servicing the power steering hoses be sure to align the hoses in their correct position as shown in Figs 13 28 It is important that the power steering hoses be installed correctly Hoses installed out of position may be subjected to chafing or other abuses during sharp turns Do not twist hoses unnecessarily during installation CAUTION 2o not start engine with any power steering hose disconnected BLEEDING POWER STEERING SYSTEMS When a power steering pump or power gear has been installed the air that has entered the system must be bled out before the vehicle is again operated If air is allowed to remain in the power steering fluid system noisy and unsatisfactory operation of the system will result Bleed air from the hydraulic system as follows NOTE When power steering fluid is added to power steering system only clean new power steering fluid should be used GM 1050017 1 Fill oil reservoir to proper level and let oil remain undisturbed for at least two minutes 2 Start engine and run momentarily 3 Add oil if necessary 4 Repeat above procedure until oil level remains constant after running engine 5 Raise front end of vehicle so that wheels are off the ground 6 Turn the wheels off ground right and left lightly contacting the wheel stop
537. ump rod Fig 4MQ Fig 1MQ A M4ME Quadrajet Carburetor TRUCK SUPP OVERHAUL 6 12 CARBURETOR Fig 2MQ Removing Upper Choke Lever CAUTION Use care in removing small roll pin to prevent damage to pump lever casting bosses in air horn 5 Remove nine air horn to bowl attaching screws two attaching screws are located next to the venturi Two long screws five short screws and two countersunk screws Fig 5MQ 6 Remove air horn from float bowl by lifting straight up The air horn gasket should remain on the float bowl for removal later Fig 6MQ Fig 3MQ Removing Secondary Metering Rods Fig 4MQ Removing Pump Lever CAUTION When removing air horn from float bowl use care to prevent bending the small tubes protruding from the air horn These tubes are permanently pressed into the air horn casting DO NOT REMOVE Air Horn Disassembly Remove front vacuum break bracket attaching screws The diaphragm assembly may now be removed from the air valve dashpot rod and the dashpot rod from the air valve lever Fig 7MQ CAUTION Do not place vacuum break assembly in carburetor cleaner Further disassembly of the air horn is not required for cleaning purposes If part replacement is required proceed as follows Fig 5MQ Removing Air Horn Screws TRUCK SUPP OVERHAUL CARBURETOR 6M 13 Float Bowl 1 Remove air horn gasket by lifting out of dowel locating pins and lifting tab of gasket from ben
538. unloader mechanism is provided should the engine become flooded during the starting period The unloader partially opens the closed choke valve to allow increased air flow through the carburetor to lean out the overly rich mixtures This is accomplished by depressing the accelerator pedal to the floor so that wide open throttle is obtained When this is done a tag on the throttle lever contacts an arm on the fast idle cam and forces the choke valve partially open The extra air leans out the fuel mixture enough so that the engine will start MAINTENANCE AND ADJUSTMENT IDLE SPEED Two idle speeds are required and are controlled and adjustable by the idle stop solenoid The purpose of two idle speeds is to prevent dieseling when ignition is turned off One speed is Curb Idle Speed which is normal engine idle and solenoid is energized The second speed is Low Idle Speed and when solenoid is de energized the carburetor throttle plate closes further than at normal engine idle Low Idle and Curb Idle Speed Adjustment Fig 9 Refer to Vehicle Emission Control Information label on vehicle for latest certified specification information which may differ from specifications in manual 1 With engine at normal operating temperature air cleaner on choke open and air conditioning OFF except where indicated connect a tachometer to engine 2 Set parking brake and block drive wheels 3 Disconnect and plug carburetor and PCV hoses at vapor c
539. ure screws until the lower specified idle speed is achieved Example 650 600 TRUCK SUPP SERVICE ENGINE FUEL 6 41 10 Connect fuel tank vent hose PUMP ROD ADJUSTMENT Fig 44 1 With fast idle cam follower off steps of fast idle cam back out carburetor idle speed screw until the throttle valves are completely closed in bore NOTE Be sure secondary actuating rod is not keeping the primary throttle valves from closing If the primary cam throttle valves do not completely close bend the HIGHEST STEP 4 secondary closing tang of position closing tang out of position and then readjust after pump adjustment MACIOME SETTING SPECIFICATIONS 3 TURN FAST IDLE SCREW IN TO CONTACT LEVER THEN SCREW IN SPECIFIED NUMBER OF TURNS TO ADJUST SEE NOTEI 2 TURN FAST IDLE SCREW 7 OUT UNTIL IT PULLS AWAY FROM CAM FOLLOWER 3 GAUGE FROM TOP OF CHOKE VALVE WALL NEXT TO VENT STACK TO TOP OF PUMP STEM AS SPECIFIED Fig 45 Fast Idle Adjustment 2 Run engine to obtain normal operating temperature ebay Breen eons 3 Position transmission in Park or Neutral 2 support LEVER idu 4 Disconnect and plug vacuum hose at EGR valve if equipped 454 engine with electric choke disconnect and plug vacuum hose to front vacuum break unit 5 Position cam follower lever on highest step of fast idle THROTTLE VALVES COMPLETELY CLOSED cam
540. ures are desired at warmer ambient temperatures AIR TEMPERATURE BETWEEN 50 AND 70 F Electric current applied to the small section or both the small and large sections of the ceramic resistor depending upon the temperature will produce the required heat to warm the thermostatic coil to control choke valve position for good engine performance in these temperature ranges NOTE Ground contact for the electric choke is provided by a metal plate located at the rear of the choke assembly DO NOT INSTALL A CHOKE COVER GASKET BETWEEN THE ELECTRIC CHOKE ASSEMBLY AND THE CHOKE HOUSING The electric choke assembly is indexed properly by aligning the scribe mark on the front cover with the specified mark on the choke housing TRUCK SUPP SERVICE 6M 40 ENGINE FUEL THERMOSTATIC COIL POST amp GROUND COVER BI METAL SNAP DISK RING 3 FINGERED SPRING x c RIVET CONTACT RIVET 2 4 D S RIVET INSULATOR TERMINAL PLATE TERMINALS ELECTRICAL CONNECTION CERAMIC RESISTOR Fig 43B Electric Choke Assembly As the thermostatic coil warms up the choke coil lever in the housing moves the choke rod up in the slot in the upper choke lever to open the choke valve further to the near wide open position while still keeping the cam follower lever on the low step of the fast idle cam In this way the fast idle speed is maintained long enough to keep the engine from stalling yet allows use of a choke coil whi
541. ust neutral start switch if necessary to provide the correct relationship to the transmission detent positions CAUTION inaccuracies in the above adjustments may result premature failure of the transmission due to operation without controls in fuil detent Such operation results in reduced oil pressure and in turn partial engagement of the affected P WASHER L WASHER GROMMET NUT F COLUMN SHIFT LEVER 77 coum ASSEMBLY 1 SIDE RAIL TRANSMISSION 7 RETAINER GROMMET SHAFT ASSEMBLY B GROMMET 77 Fig 2G Column Shift Linkage G Series clutches Part al engagement of the clutches with sufficient pressure to cause apparent normal operation of the vehicle will result in failure of the clutches or other internal parts after only a few miles of operation DETENT DOWNSHIFT CABLE Figs 3G and 4G Removal 1 Push up on bottom of snap lock and release lock and detent downshift cable 2 Disconnect cable from carburetor lever 3 Compress locking tabs and disconnect snap lock assembly from bracket 4 Remove clamp around filler tube remove screw and washer securing cable to transmission and disconnect detent downshift cable Installation 1 Install new seal on detent downshift cable lubricant seal with transmission fluid 2 Connect transmission end of detent downshift cable and secure transmission case with bolt and washer tightened to 75 inch pounds 3 Route cable in front of filler tub
542. vacuum sensitive power piston and power valve are used for power requirements When manifold vacuum drops to a pre determined point called power cut in the power piston moves downward against spring tension to force the power valve plunger off its seat Fuel then flows from the float bowl down past the valve plunger through a small calibrated orifice in the valve side and on into separate fuel channels leading to the power restrictions The fuel passes through the power restrictions into the main fuel wells for desired enrichment at the main discharge nozzles The power valve located at the bottom of the fuel bowl provides the correct fuel enrichment for power requirements MANIFOLD VACUUM 7 lvyvACUUM RELIEF PASSAGE POWER PISTON 4 RESTRICTIONS MAIN WELL Fig 24 Power Enrichment System TRUCK SUPP SERVICE PUMP SYSTEM Fig 25 When the throttle valve is opened rapidly air flow and manifold vacuum change almost instantly while the heavier fuel tends to lag behind causing a momentary leanness The accelerator pump system provides the fuel necessary for smooth operation on rapid acceleration PUMP DURATION DISCHARGE PASSAGE SPRING EXPANDER INLET CHECK SPRING BALL Fig 25 Pump System Fuel for acceleration is supplied by a double spring loaded pump plunger The top and bottom springs combine to move the plunger so that a smooth sustained charge of fuel is delivered for accelerat
543. val This procedure will include removal of the converter support bracket TRUCK SUPP SERVICE 7 4 AUTOMATIC TRANSMISSION nr 7 C K 350 4 AND P MODELS C K 350 2 MODEL Fig 4G Detent Downshift Cable CK and P Series DIAGNOSIS OIL PRESSURE CHECK While vehicle 1 stationary service brake on engine speed set to 1200 rpm transmission oil pressure gauge attached and vacuum modulator tube disconnected the transmission to line pressure tap should read 167 psi in drive 166 psi in L1 or L2 and 254 psi in reverse for the 350 V 8 While vehicle is stationary service brake on engine speed set to maintain 12 inches hg absolute manifold pressure transmission oil pressure gauge attached and vacuum modulator tube connected the transmission should read 85 psi in drive 105 psi in L1 or L2 and 129 psi in reverse for the 350 8 SPRING TENSION COMPARISON CHECK Using tool J 2466 as shown in Figure 5G compare the load of a known good modulator with the assembly in question a Install the modulator that is known to be acceptable on either end of the tool b Install the modulator in question on the opposite end of the tool c Holding the modulators in a horizontal position bring them together under pressure until either modulator sleeve just touches the tool The indicator in the gage wil show white if the modulator TRUCK SUPP SERVICE J 24466 HOLD MODULATORS IN A HORIZONTAL POSITION AS
544. ve replace with a factory matched set 3 Check float for being loaded with fuel bent float hanger or binds in the float arm NOTE A solid float can be checked for fuel absorption by lightly squeezing between fingers If wetness appears on surface or float feels heavy check with known good float replace the float assembly 4 1f excessive dirt is found in the carburetor clean the fuel system and carburetor Replace fuel filter as necessary TRUCK SUPP SERVICE Problem ENGINE FUEL 6M 27 ENGINE CRANKS TURNS OVER BUT WILL NOT START OR STARTS HARD WHEN COLD POSSIBLE CAUSE Improper starting procedure used No fuel in gas tank Choke valve not closing sufficiently when cold Choke valve or linkage binding or sticking Inoperative choke or vacuum break No fuel in carburetor Engine Flooded NOTE To check for flooding remove air cleaner with engine off and look into carburetor bore Fuel will be dripping off nozzle and or carburetor will be very wet Carburetor flooding CORRECTIVE ACTION Check proper starting as outlined in the owner s manual Add fuel Check fuel gauge for proper operation Adjust the choke coil rod Realign the choke valve or linkage as necessary If caused by dirt and gum clean with automatic choke cleaner Do not oil choke linkage parts are replaced check adjustments 1 Inspect choke and vacuum break for worn or missing parts Replace and adjust as require
545. ve coolant recovery tank and empty of fluid Clean inside of tank thoroughly with detergent and water scrubbing sides clean and then flush with clean water and drain Reinstall tank C K Models Insert coolant recovery hose in tank as far as the first white stripe Fig 5 Fig 5 Coolant Recovery System CK Series ENGINE 6K 3 Fig 6 Coolant Recovery System G Series 9 Add sufficient ethylene glycol coolant meeting GM specification 1899 M to provide the required freezing and corrosion protection at least a 50 percent solution 207F Completely fill radiator and add sufficient coolant to the recovery tank to raise the level to the Cold Level mark Reinstall recovery tank cap 10 Pressure check cooling system BRACKE Fig 7 Coolant Recovery System P30 42 TRUCK SUPP SERVICE 6K 4 ENGINE Fig 8 Coolant Recovery System P30 32 COOLANT RECOVERY SYSTEM Refer to Figures 5 through 8 for removal and installation of applicable coolant recovery system Inside of coolant recovery tank should be clean before installing in a vehicle TRUCK SUPP SERVICE SECTION 6M ENGINE FUEL CONTENTS OF THIS SECTION IMV Carburetor 2GC Carburetor M4MC M4ME Carburetor 4 Quadrajet Carburetor Accelerator Control Alt Cleaner o says Fuel Pump e Special Tools
546. ve hose with compressed air Replace deteriorated hoses The PCV filter located in the air cleaner should be replaced whenever the air cleaner element is replaced C 9 IDLE STOP SOLENOID Check for proper operation An inoperative solenoid must be replaced C 10 SPARK PLUG WIRES Clean exterior of wires remove any evidence of corrosion on end terminals Inspect spark plug wires for evidence of checking burning or cracking of exterior insulation and tight fit at distributor cap and spark plugs or other deterioration If corrosion cannot be removed or other conditions above are noted replace wire 11 SPARK PLUGS Replace plugs at 22 500 mile intervals for V8 engines and 30 000 miles for L 6 engines with type specified in Section 6 of this manual OO u I a i Al T q A hh C 12 TIMING AND DISTRIBUTOR CAP Adjust ignition timing following the specifications shown on label under the hood Also carefully inspect the interior and exterior of the distributor cap and rotor for cracks carbon tracking and terminal corrosion Clean or replace as necessary C 13 EVAPORATION CONTROL SYSTEM ECS Check all fuel and vapor lines and hoses for proper connections and correct routing as well as condition Remove canister and check for cracks or damage Replace damaged or deteriorated parts as necessary Replace filter in lower section of canister C 14 FUEL CAP FUEL LINES AND FUEL TANK Inspect the fuel tank cap and lines fo
547. ve in the bore of the throttle body do not remove the throttle valve or shaft THROTTLE LEVER THROTTLE VALVE SPARK PORTS Fig 6 Throttle Body Assembly TRUCK SUPP OVERHAUL mnr x m ONG NEN UE euge eee c n I aw rr s 6M 4 CARBURETOR CLEANING AND INSPECTION The carburetor should be cleaned in a cold immersion type cleaner 1 Thoroughly clean carburetor castings and metal parts in an approved carburetor cleaner such as Carbon X X 55 or its equivalent Rubber and plastic parts should not be immersed in carburetor cleaner However the air horn which has the plastic relief valve will withstand normal cleaning in carburetor cleaner Blow out all passages in castings with compressed air Do not pass drills through jets or passages Examine float needle and seat assembly for wear Install a new factory matched set if worn Inspect upper and lower casting sealing surfaces for damage Inspect holes in levers for excessive wear or out of round condition If levers are worn they should be replaced Examine fast idle cam for excessive wear or damage Check throttle and choke levers and valves for binds and other damage Check all springs for distortion or loss in tension replace as necessary NOTE When carburetor has been disassembled new gaskets and filter must be used ASSEMBLY Throttle Body l 2 3 Invert float bow and install new throttle body to
548. vehicle that could obscure vision or become an injury hazard TRUCK SUPP SERVICE t DOOR LATCHES for positive closing latching and locking u HOODLATCHES Check to make sure hood closes firmly by lifting on the hood after each closing Check also for broken damaged or missing parts which might prevent secure latching v FLUID LEAKS Check for fuel water oil or other fluid leaks by observing the ground beneath the vehicle after it has been parked for a while Water dripping from air conditioning system after use is normal If gasoline fumes or fluid are noticed at any time the cause should be determined and corrected without delay because of the possibility of fire w SPARE AND JACK Check that spare tire assembly and jack equipment are securely stowed at all times B 2 TIRES AND WHEELS To equalize wear rotate tires as illustrated in Section 10 Adjust the tire pressures as recommended on tire placard on rear face of driver s door Check disc brake pads and condition of rotors while wheels are removed Check tires for excessive wear or damage Make certain wheels are not bent or cracked and wheel nuts are tight Check tire inflation pressure at least monthly or more often 1f daily visual inspection indicates the need B 3 EXHAUST SYSTEM Check complete exhaust system and nearby body areas for broken damaged missing or mispositioned parts open seams holes loose connections or other deterioration
549. ween air horn wall and upper edge of choke valve using specified gauge 5 Bend vacuum break rod if adjustment is required CHOKE UNLOADER ADJUSTMENT FIG 140 1 Push up lightly on vacuum break lever to close choke Hold in position with rubber band 2 AIR VALVES MUST BE COMPLETELY CLOSED n pu t 027 BEND ROD HERE AE E TO OBTAIN SPECIFIED CLEARANCE BETWEEN ROD AND END OF SLOT IN LEVER 1 DIAPHRAGM lt SEATED val USE OUTSIDE Y VACUUM SOURCE 3 PLACE GAUGE BETWEEN ROD AND END OF SLOT IN LEVER Fig 12Q Air Valve Dashpot Adjustment TRUCK SUPP SERVICE 6M 62 ENGINE FUEL 9 GAUGE BETWEEN AIR HORN WALL AND UPPER EDGE OF CHOKE VALVE VACUUM PLUNGER MUST BE FULLY SEATED USING OUTSIOE VACUUM LIGHTLY ROTATE CHOKE COIL LEVER COUNTERCLOCK WISE UNTIL END OF ROD 1 IN END OF SLOT IN LEVER OPEN PRIMARY THROTTLE VALVES SO THAT FAST IDLE CAM FOLLOWER CLEARS TO ADJUST FAST IDLE CAM Fig 130 Break Adjustment 2 Hold primary throttle valves wide open 3 Position specified gauge between air horn wall and upper edge of choke valve 4 If opening is incorrect bend tang on lever to adjust 3 GAUGE BETWEEN AIR HORN WALL AND UPPER EDGE OF CHOKE VALVE NJ LEVER TOWARDS CLOSED L CHOKE T 2 HOLD PRIMARY THROTTLE VALVES WIDE OPEN Ss amp m L Fig 14Q Choke Unloader Adjustment CHOKE COIL ROD ADJUSTMENT FIG 15
550. which leads into the main well from the discharge nozzle cavity After the fuel in the main well is mixed with air from the air bleeds it then passes up the discharge nozzle where it sprays into the small boost venturi At the boost venturi the fuel mixture then combines with air entering the engine through the carburetor bore to provide the correct air fuel mixtures to the engine for efficient combustion MAIN WELL AIR BLEED POWER PISTON METERING ROD MAIN DISCHARGE NOZZLE POWER PISTON BOOST VENTURI MAIN VENTURI MAIN METERING JET CALIBRATION POWER PISTON ACTUATING LINKAGE LOWER IDLE AIR BLEED POWER PISTON VACUUM THROTTLE VALVE piis Fig 4 Main Metering System TRUCK SUPP SERVICE Fuel flow to the main discharge nozzle is controlled by a tapered metering rod which is actuated by linkage connected directly to the throttle shaft As the throttle valve is opened from idle position the tapered metering rod is gradually raised out of the main metering jet orifice Fuel flow from the main discharge nozzle is controlled by throttle opening and the depth of the metering rod in the main metering jet orifice With the fuel metering mechanically controlled by the throttle valve angle it is possible to maintain very accurate mixture ratios throughout part throttle to wide open throttle operation An initial metering rod adjustment is required to set the depth of the rod in the main metering jet CAUTION t
551. will be applied to the inner race of the bearing when installing the assembly on the front head of the compressor 5 Install rotor and bearing using Snap Ring Pliers J 6083 6 Assemble and fully seat pulley rim to clutch rotor and bearing assembly as shown in Figure 84 using Loctite RC 75 or equivalent on screw threads and use new lockwashers Do not torque mounting screws to final torque limits until pulley rim is checked to be rotating jn line 7 Tighten pulley rim mounting screws to a 100 inch pounds torque and lock screw heads in place as shown in Figure 84 8 Assemble clutch plate and hub assembly as described under Compressor Clutch Plate and Hub Assembly CLUTCH COIL AND PULLEY RIM REPLACEMENT Removal 1 Perform Compressor Clutch Rotor and Bearing Assembly Removal but do not loosen or remove pulley rim mounting screws until clutch rotor coil and pulley rim assembly have been removed from front head in Step 4 2 Remove pulley rim mounting screws and slide pulley rim off rotor and hub assembly The pulley rim and J 25029 Fig 82 Removing Clutch Rotor Bearing clutch coil are replaceable at this point Installation 1 Assemble clutch coil pulley rim and clutch rotor and bearing assembly as shown in Figure 80 using Loctite RC 75 or equivalent on screw threads and using new lockwashers but do not lock screw heads in place Place assembly on neck of front head and seat into place using
552. wing step 10 carefully CAUTION Srep 10 must be performed if the window 1s removed or disengaged from the regulator ift arms The lift arms are under tension from the counter balance spring can cause injury if the motor Is removed without locking the sector gears position TRUCK SUPP SERVICE BODY 1 3 G MODELS Fig 5 Control and Latches REAR DOOR ITEMS Latches Strikers and Wedges Figures 5 and 6 illustrate the new latches strikers wedges and adjustment dimensions for G Model rear doors Refer to pages 1B 44 and 1B 45 of the 1974 Light Duty Truck Service Manual for replacement instructions Note the new dimensions for striker adjustments QUICK RELEASE BENCH SEAT G VAN Fig 7 All models equipped with 2nd 3rd and 4th bench seat assemblies feature a quick release mechanism which facilitates removal of the seats for added cargo space Instead of the conventional clamp and bolt method of seat retention cam type latch assemblies and hooked retainers which fit onto anchor pins in floor anchor plates are used When the latch assemblies are depressed their cams and the hooks of the retainers are drawn tightly onto the anchor pins for secure seat attachment WEDGE ADJUSTMENT 04 MAX CLEARANCE IN SECONDARY LATCHED POSITION OR 010 TO 050 INTERFERENCE IN FULL LATCHED POSITION UPPER STRIKER ADJUSTMENT 17 03 11 64 DRILL IN SECONDARY LATCHED POSITION
553. with clean 525 viscosity refrigerant oil Mount the seal seat on Seal Seat Remover Installer J 23128 and install it in the compressor neck taking care not to dislodge the seal TRUCK SUPP OVERHAUL 1 10 AIR CONDITIONING COMPRESSOR INSTALLER J 9392 N SEAL di PROTECTOR J 22974 WIRE GAGE 026 SHOULD GO 075 SHOULD NOT GO SEAL SEAT RETAINER RING SEAL ASSEMBLY Fig 21 Compressor Shaft and Seal seat O ring and being sure the seal seat makes a good seal with the O ring Remove Seal Protector J 22974 from the end of the shaft see Fig 19 Install the new seal seat retainer ring with its flat side against the seal seat using Snap Ring Pliers J 5403 321 See Fig 18 Use the sleeve from Seal Seat Remover Installer J 23128 Fig 19 to press in on the seal seat retainer ring so that it snaps into its groove Install Compressor Leak Test Fixture J 9625 on rear head of compressor and connect gage charging lines as shown for bench test in Fig 22 or pressurize SUCTION SIDE of compressor on car with Refrigerant 12 vapor to equalize pressure to the drum pressure Temporarily install the shaft nut and with compressor in horizontal LEAK TEST SU PERHEAT ADAPTER SHUTOFF J 9625 SWITCH OIL FITTING Fig 22 Leak Testing 6 Compressor position and oil sump down rotate the compressor shaft in normal direction of rotation several times by hand Leak test the seal with an
554. y 4 Manually hold air valve closed 5 Turn tension adjusting screw clockwise specified number of turns after spring contacts pin 6 Tighten lockscrew and replace air valve dashpot rod and vacuum break diaphragm unit and bracket Throttle Lever Actuator Adjustment Fig 18Q For additional information refer to Section 6T Throttle Return Control System 1 Disconnect valve to actuator hose at valve and connect to an external vacuum source equipped with a vacuum gauge 2 Check the throttle lever shaft and linkage to be sure that they operate freely without binding or sticking 3 Start engine and run until warmed up and idle is stable Place transmission in neutral or park 4 Apply 20 in Hg vacuum to the actuator Manually open the throttle slightly and allow to close against the extended actuator plunger Note the engine RPM 5 If the RPM noted above is not within the specified Throttle Return Control TRC speed range then turn the screw on the actuator plunger in the appropriate direction and repeat step No 4 until the specified TRC speed range is obtained 3 WITH PLUNGER HELD INWARD TURN PLUNGER SCREW IN OR OUT TO OBTAIN SPECIFIED DECEL RPM L 2 WITH ENGINE AT SPECIFIED IDLE SPEED 1 ADJUST IDLE SPEED PUSH IN ON END OF SCREW TO OBTAIN rJ PLUNGER UNTIL SEATED SPECIFIED RPM VACUUM OPERATED DECELERATION CONTROL Fig 18Q Throttle Lever Actuator TRUCK SUPP SERVICE 6 64 ENGINE FUEL
555. y three inches 10 Install through bolts in engine mount and tighten through bolts retaining nuts just enough to prevent bolts from slipping out 11 Lower engine until through bolts are resting on frame portion of engine mounts and then remove jacking device 12 Remove screws securing oil pan to engine and then remove oil pan Installation Fig 4L 1 Thoroughly clean all gasket sealing surfaces 2 Use a new gasket set and install rear pan seal in rear main bearing cap 3 Install front pan seal on crankcase cover pressing tips into holes provided in cover 4 Install side gaskets to engine block using gasket sealer with sufficient body to act as a retainer 5 Install oil pan by reversing the removal steps and tightening all retaining screws to specifications THROUGH BOLT 2 ENGINE MOUNT 2 gt 4 5 E Fig 4L Oil Pan Replacement ENGINE 6 3 ENGINE MECHANICAL V 8 ENGINES GENERAL INFORMATION All vehicles utilize a high energy ignition system Using this system the conventional external ignition coil and other related components are eliminated Except for the following changes all information listed in Section 6 Engine of the 1974 Light Truck Service Manual is applicable to the 1976 model COMPONENT REPLACEMENT AND ADJUSTMENT INTAKE MANIFOLD The intake manifold removal and installation procedure remains basically the same except that a new carburetor
556. zation in running the engine Refer to Section 8 in the 1974 Light Duty Truck Service Manual for service procedures M 22 ou ES C Carburetor Hot Air Meters and mixes heated air with incoming cold air to optimize fuel vaporization Refer to Section 6M for service procedures of air cleaner and air intake duct Controlled Combustion System CCS Increases combustion efficiency through leaner carburetor mixtures and revised distributor calibration Thermostatically controlled damper in the air cleaner silencer maintains warm air intake to carburetor Refer to Section 6M for air cleaner service procedures Air Injection Reactor A I R California Except L6 Engine Compresses regulates and distributes quantities of air to the exhaust to more completely burn carbon monoxide and hydrocarbon emissions Refer to 1974 Light Duty Truck Service Manual for service procedures Throttle Return Control TRC When vehicle is coasting against engine throttle lever actuator pushes throttle lever slightly open to reduce hydrocarbon emission during coast down Service procedures are included in this section AIR INJECTION REACTOR SYSTEM The air injection reactor system remains basically the same in theory and operation with the following addition Air is injected into the front exhaust pipe forward of the cat

1976 Service Manual - 73

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