MARVEL-SCHEBLER - The Old Car Manual Project
Contents
1. Install Choke Assembly Parts Choke Valve and Screws Before assembling dust cap attach the choke flex spring as shown in illus tration below 21B Attach Choke Flex Spring With choke valve in open position attach spring to pins on choke lever and shaft as shown 22 Install Idle Adjusting Needle Set approximately 1 turns from seat for pre liminary setting NOTE Idle needle brass plated to distinguish 23 Install Load Adjusting Needle Set approximately 1 turn from seat for preliminary setting NOTE Load needle cad mium plated gray color to distinguish 24 Install Nozzle Tap bottom of the nozzle lightly to seat in casting Before assembling carbureter clean castings channels and parts with carbureter cleaning fluid and air under pressure Make certain all small holes and channels are open and free from carbon and dirt Do not use wire or small drills to clean out small holes as a slight change in size of these holes will affect the carbureter operation Gum deposits not removed by carbureter cleaning fluid clean with a lacquer thinner To assure a successful overhaul always replace all worn or damaged parts and any parts that are questionable Always use new gaskets Page 17 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Service Instructions for Model DLTX Carbureters 25 Install Float and Lever Assembly amp Float2. SERVICE MANUAL for MARVEL SCHEBLER TRACTOR and INDUSTRIAL CARBURETERS MODELS DLTX amp TSX MARVEL SCHEBLER PRODUCTS DIV BORG WARNER CORPORATION DECATUR ILL U S A Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Principle of Operation Marvel Schebler Carbureters are used on thousands of tractor and industrial engines and have been designed to provide many years of trouble free service however as in the case of all mechanical devices they do in time require proper service and repairs An understanding of their construction and how they operate as well as an understanding of their function with respect to the engine will not only avoid many false leads on the part of the service man in diag nosing so called carbureter complaints but will vreate customer satisfaction and a profitable business for the progressive service shop To understand a carbureter it is necessary to realize that there is only one thing that a carbur eter is designed to do and that is to mix fuel and air in the proper proportion so that the mixture will burn efficiently in an engine It is the func tion of the engine to convert this mixture into power There are three major factors in an engine which control the change of fuel and air into power 1 Compression 2 Ignition 3 Car buretion Carburetion has been listed last because it is absolutely necessary for the engine to have good co
3. A dual float mechanism Figure 3 is used in a fuel bow that almost com pletely surrounds the nozzle This de sign and construction is such that the tractor or engine can be operated at any angle up to 45 degrees without seriously affecting the fuel and air ratio and without flooding because the mean level at the nozzle tip is practi cally constant at any angle of opera tion Some carbureters are equipped with a spring loaded governor control lever to permit manual closing of the throttle to an idle position for engines equipped with certain type governors An example of this type lever is shown in Figure 4 however there are other variations of this type dependent upon the particular application While there are many variations produced by combining the different types and sizes into a specific application all Model TSX carbureters incorporate the same engineering principles and are alike from a functional standpoint Fig 4 Spring Loaded Governor Lever Page 8 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Service Instructions for Model TSX Carbureters MARVEL MARVEL i i AE SCHEBLER SCHEBLER Type A Fixed Jet Type B Adjustable Jet Type C Adjustable Jet The following procedure for service of all Model TSX Carbureters is for a complete overhaul After removing carbureter from engine wash thoroughly with cleaning fluid such as gasoline to permit exam
4. the road equipment it is possible to wear the cylinder walls down one thousandths of an inch in 50 hours of operation as a result of leakage around a worn throttle shaft Make sure on all engine overhaul and tune up jobs that the carbureter is removed cleaned and all worn parts replaced Remember it s not the air which is drawn into the engine around worn shafts which wears out rings valves and cylinder walls it s the dust and dirt in the air Dirt Is Engine Enemy No 1
5. Illinois U S A Model TSX Carbureter IDLE ADJUSTING NEEDLE FUEL IDLE ADJUSTING NEEDLE AIR NOZZLE POWER JET BOWL DRAIN AP ik POWER ADJUSTING NEEDLE Fig 1 Idle and Power Fuel Feed Systems The Marvel Schebler Model TSX Carbureter is manufactured in three S A E nominal sizes inch 1 inch and 114 inch In addition to these vari ations in size there are also variations necessitated by the specific require ment of the engines on which the car bureters are used Many engines for instance require special throttle and choke operating levers and for pur pose of calibration they may have dif ferent size jets nozzles venturii etc For this reason when ordering parts refer to the individual carbureter serv ice parts list for the engine on which the carbureter is installed The Model TSX Carbureter consists of only two major castings 1 The throttle body casting which forms the cover for the fuel bowl 2 The fuel bowl casting which con tains the air inlet Cast iron material is used for rug gedness It will be noticed Figure 1 that all passages whenever possible are drilled from the top face of the fuel bowl casting to prevent any fuel leaks to the outside of the carbureter because of shrunken gaskets or defec tive hole plugs and also to prevent vapor lock or percolation of the fuel when the carbureter is operated under ex tremely hot conditions resulting in ha
6. 9 NSS ERS the throttle valve 6 since this valve must be slightly open to permit the engine to idle The resultant mix ture is correct for operat ing engine at idle speed provided the idle adjust ing needle 13 is prop erly adjusted As the throttle valve 6 is slowly opened from the slow idle position it gradu ally subjects the second ary idle orifice 8 to in take manifold vacuum and the secondary idle orifice 8 no longer bleeds air to the idle fuel passage 10 but feeds an addi tional quantity of fuel into the engine This is proper since the throttle valve is now open wider and will admit a greater amount of air to blend with this additional fuel to maintain the correct proportions of fuel and air for the engine IDLE ADJUSTING NEEDLE 13 As the throttle valve 6 is opened still wider the idle fuel delivery begins to fade out how ever the throttle valve at this point is far enough open for the power fuel feed system to begin functioning The idle system as described above is the most positive and satisfactory of idle systems as it is working under very high suction and the mixture flows through the small passages and orifices at very high velocities It is necessary to bear in mind however that there are times when these small holes may become plugged with particles of dirt or foreign matter and will require clean ing At such times the passages jets and small drilled
7. On Models DLTX 26 and DLTX 46 use Tool No M 131 16 Install Lower Shaft Bush ing Open End Bushing Place new lower bushing on Tool No M132 and drive bushing in casting up to shoulder on tool 16A Install Throttle Shaft Hole Plug Drive plug flush with face of lower throttle shaft bushing boss 16B Install Lower Shaft Bush ing Blind End Bushing Drive bushing until flush with face of casting boss Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Service Instructions for Model DLTX Carbureters 17 Install Upper Shaft Bushing Place new upper bushing on pilot of Schebler Tool No 2604 and drive bush ing into body until flush with top of casting boss Use Tool No M 129 for Models DLTX 26 and DLTX 46 18 Ream Throttle Shaft Bushings If throttle shaft binds in bushings ream bushings with special reamer Scheb ler Tool No 2606 Use reamer Tool No M 128 for Models DLTX 26 and DLTX 46 Assemble 19 Install all Channel Plugs and Economizer Plug Install new economizer plug if plug is nicked or damaged 20 Install Throttle Shaft and Lever Assembly Valve and Screws Tap valve lightly to cen ter in throttle bore Tight en screws 21 Install Choke Shaft and Lever Assembly Choke Valve and Screws Center valve in casting be fore tightening screws 21A
8. Screws Center valve in casting before tightening screws 27 Install Power Jet Type A Type B 28 Install Main Nozzle and Gasket Type A Type B Use new gasket Page 11 29 Install Main Nozzle and Gasket Type C Use new gasket 30 Install Power Adjusting Needle Assembly Type C Use new gasket Set approximately one turn from seat for preliminary setting 31 Install Gasoline Drain Strainer amp Retainer Plug Stake retainer plug in place with center punch to insure secure locking Adjustment PRELIMINARY ADJUSTMENTS Set throttle stop serew so that throttle valve is open slightly Make certain that fuel supply to carbureter is open Close choke valve Start engine and partially release choke After the engine has been run sufficiently to bring up to operating temperature throughout see that choke is returned to wide open position LOW SPEED OR IDLE ADJUSTMENT Set throttle or governor control lever in slow idle position and adjust throttle stop screw for the correct engine idle speed On a new stiff engine this speed must be slightly higher than required for a thoroughly run in engine Turn idle adjusting needle until engine begins to falter or roll from richness then turn needle in the opposite direction until the engine runs smoothly NOTE It is better that this adjustment be slightly too rich than too lean 32 Assemble Castings Invert t
9. Valve TYPE A Before installing float sub merge in pan of hot wat er Replace if air bubbles are observed escaping from float 26 Install Float Lever Pin and Float Lever Bearing Screws Type A 27 Install Float Valve Seat and Gasket Type A Use new gasket Examine action of float Be sure there is no sticking be tween fingers on float lev er and head of float valve 28 Set Float Level Type A Set float 14 on models DLTX 3 to DLTX 63 in clusive Set float on models DLTX 67 to DLTX 73 in clusive Measure from top of fuel bowl to top of float Use Schebler Tool No 35 to bend float lever ADJUSTMENT PRELIMINARY ADJUSTMENTS Set speed control lever so that throttle valve is open slightly Make certain that fuel supply to carbureter is open Close choke yalve Start engine and partially re lease choke After engine has been run sufficiently to bring up to operating temperature throughout see that choke is returned to wide open position IDLE ADJUSTMENT Advance speed control lever to wide open throttle position which will be fast idle or governor controlled idle Adjust idle adjusting needle until engine runs evenly NOTE To enrich the idle mixture turn idle adjusting needle to the left or counter clockwise 29 Install Fuel Strainer Assembly Type A Always use a new strain er gasket 30 Install Float Valve Seat Gasket and
10. any parts that are questionable Always use all new gaskets i aaaaaaaaaaaaaaalauaaaaaualauaasasasasasauastulululssultlltllssssSsSMSMl Page 10 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A 19 Install Economizer Jet 20 Install Idle Jet 21 Install Idle Adjusting Needle and Spring Set approximately one turn from seat for preliminary setting 22 Install Float Valve Seat and Gasket Use new Float Valve and Seat Assembly 23 Assemble Bowl Cover Gasket and Venturi in Casting Install float valve 24 Install Float and Lever Ass mbly and Float Lever Pin Set floats 14 from gasket face to nearest edge of float keeping edge of float parallel with gasket Ad Just by using bending tool 25 Install Choke Shaft Packing Retainer and Packing MARVEL Install retainer as shown SCHEBLEAR in illustrations below Note On some carbureter models the packing is re tained by choke bracket in place of packing retainer 25A On carbureters counter bored to amp deep in stall retainer with cup facing towards casting Tap lightly until flush with casting face 25B On carbureters counter bored 3 to deep in stall retainer with cup facing away from casting Tap lightly until flush with casting face 26 Install Choke Bracket Choke Return Spring Choke Shaft and Lever Assembly Valve and
11. is dis assembled for whatever cause the service man make following checks 1 Examine float valve for any signs of wear If it is not absolutely true or is grooved and hasn t a N perfect taper a new N float valve and also a N new float valve seat N must be used These N float valves and seats N are supplied in match N ed sets and are tested S at the factory for leaks Always use a new float valve seat gasket to make sure of a perfect seal 2 Examine float for any signs of failure To test metal float submerge float in pan of hot water and if air bubbles are observed replace with new float Examine cork float for bare places or cracks in coating If either are found or if float shows evidence of having been soggy replace with new one Do not attempt to recover float with shellac or varnish Set float height to the proper specification for the particular model carbureter being serviced Make certain that the entire assembly works free and that there is no binding Wash fuel strainer assembly in gasoline and clean screen with air under pressure If the screen or the threads on the strainer are not in good condition install a new assembly When re installing fuel strainer assembly always use a new strainer gasket if a gasket is used to obtain a seal It has been proven with few exceptions that with a float system in good order carbureter flooding only occurs when dirt or foreign matter becomes
12. needle el Page 12 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Model DLTX Carbureter THROTTLE BODY FUEL STRAINER ASSEMBLY z SEDIMENT CUP DRAIN PLUG A 4j FLOAT VALVE Es FLOAT VALVE FLOAT if THROTTLE LEVER STOP SPRING CHOKE VALVE LOAD ADJUSTING ee ae p PS NOZZLE FUEL BOWL NOZZLE RETAINING SPRING Fig 1 Choke Float and Power Fuel Feed Systems The Marvel Schebler Model DLTX Carbureter is a horizontal type carbureter used on John Deere tractors To meet the specific engine re quirements of the individual tractor on which the carbureter is installed requires different size jets nozzles venturi throttle and choke oper ating levers etc For this reason when ordering parts always refer to the individual carbureter service parts list for the engine on which the carbureter is installed The Model DLTX Carbureter consists of two castings 1 The throttle body casting which contains the air inlet 2 The fuel bowl casting The throttle body casting contains in addition to the throttle assembly a venturi machined in the casting and the choke assembly Cast iron materia is used for ruggedness All passages whenever possible are drilled within the cast ing to prevent any fuel leaks to the outside of the carbureter because of shrunken gaskets or defective hole plugs The Model DLTX Carbureter is completely sealed against dust o
13. through the nozzle air bleeds 15 into the nozzle 14 But because the size of the power jet 20 and the position of the power ad justing needle 18 restrict the amount of fuel which can enter the nozzle 14 the fuel in the accelerat ing well 16 will soon be exhausted and air will then enter through the nozzle air bleeds 15 to mix with the fuel passing through the nozzle 14 The amount of air that can enter into the nozzle 14 is limited by the size of the nozzle air vent 21 The result of air bleed ing into the nozzle 14 is to help atomize or break up the fuel into finer par ticles to regulate the quan tity and the rate of dis charge of the fuel fed from the accelerating well 16 during acceleration and to provide the correct mixture proportions for full throttle operation As the throttle valve is opened toward the wide open position the velocity through the ven turi 17 continues to increase lowering the air pressure at the nozzle 14 and resulting in additional fuel being supplied to the engine as the speed is increased When the throttle valve 6 is opened sud denly from slow or just off slow idle position the fuel stored in the accelerating well 16 is forced out through the nozzle air bleeds 15 very rapidly and serves to provide the extra richness required by the engine to meet the sudden load When the throttle valve 6 is closed fuel again fills the accelerating well 16 ready
14. Float Valve Type B Use new gasket 31 Set Float Level Type B Before installing the float submerge in pan of hot water Replace if air bubbles are observed es caping from float Set the float 4 from lower flange face to nearest edge of float 32 Assemble Castings Use new bowl gasket and bowl retaining nut gasket Tighten bowl retaining nut securely INSTRUCTIONS LOAD ADJUSTMENT To secure maximum fuel economy with tractor pulling load turn the load adjusting needle to the right or clock wise until the power drops appreciably Then turn the needle to the left or counter clockwise until the engine picks up power and runs smoothly Due to variations in temperature or fuels it may be necessary to richen up this mixture by backing out the power adjusting needle a small amount at a time until good acceleration is obtained If when load is released governor closes throttle clear shut causing uneven running or hunting governor opening and closing turn the throttle stop screw against the throttle lever stop spring until the hunting is cor rected and idling is satisfactory Normally there is 74 clearance between the throttle stop screw and the throttle lever stop spring at fast idle eS Page 18 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Service Complaints IDLE UNEVEN IN OPERATION The idle construction used in Marvel S
15. From the gasket to the top of the float MA All except MA 4 5 010e T0 vec ee From the top of the float to the gasket VU Ae AU og ee any chev cae e sas S From the top of the float to the gasket EN ects a oe EE From the bowl cover face to the bottom of the float AEN a cet user enaieeesane ar PEDE OS From top of float to flange gasket SP CERO ly N See neve 3 6 eRe From upper bowl gasket to bottom of float TRE ven erase ie edeneinc ccs Tinana From the gasket to the bottom of the float bit ua T A E EET GALES ter er From the gasket to the nearest surface of the float TSV A From the gasket to the nearest surface of the float TDK e apaiia E AN From the face of the flange to the bottom of the float TVET EE Se EAEE AS FEW ori From the gasket to the end of float furthest from hinge pin EIE E e AEE E D aaar From the nozzle boss to the end of the float furthest from hinge pin LS T D N a eRe nee AREN From the gasket flange face to the bottom of the float NOTE Changing the float setting from our standard in an effort to improve the operation of the carbureter or in an effort to prevent flooding will only result in faulty carbureter operation SPECIAL SERVICE NOTE How to Give Your Engines Longer Life A loose throttle shaft and worn packings will allow coarse highly abrasive dirt to be pulled into the engine It has been proved by actual test that under extreme dust conditions such as encountered by off
16. amber and additional fuel flows to the engine to provide the extra richness required for operation at heavy loads where maximum horsepower is necessary The Back Suction Economizer System as sures the proper metering of fuel to the engine throughout the service life of the carbureter as there are no moving parts to wear out or adjust ments to get out of order It is essential how ever that the system remain free of dirt and foreign matter because any foreign substance in the system will restrict the flow of air thereby creating improper pressures in the fuel bowl chamber and resulting improper fuel delivery to the engine Page 5 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Choke System The choke system is used during cold starting and the warm up period Under these cold con ditions it is necessary to supply an additional rich mixture of fuel and air as only the light ends or more volatile portions of the fuel will vaporize with the manifold and air tempera tures at these cold conditions Consequently it is necessary that a large quantity of fuel be available so that there will be enough light ends to combine with the air to form a com bustible mixture for starting the engine The function of the choke valve 25 is to restrict the amount of air that can enter the car bureter and to increase the suction on the nozzle 14 so that additional fuel will be
17. chebler Tractor and Industrial Carbureters is the most positive and satisfactory of idle systems because it is working under very high suction and the mixture flows through the small passages at very high velocities It is necessary to bear in mind however that there are times when these small holes may become plugged with particles of dirt or lint but very seldom If idle trouble is experi enced first check the manifold to cylinder head gasket and the carbureter to manifold gasket for air leaks At slow idle an engine requires only approximately 20 to 25 lbs of air per hour and a slight leak will result in a very erratic or rough idling engine Other causes for a ruugh idling engine are uneven compression caused by sticky or leaking valves leaking valve seats tappets with im proper clearances leakage past pistons and rings cylinder head gasket leaking weak spark or spark plug points not spaced correctly ignition cable covering cracked and thus ground ing spark and cable not assembled properly in the distributor cap which causes corrosion and weak spark The spark timing of the engine is most im portant and should also be checked very care fully and set exactly on the mark as called for in factory standard specifications In fact all of the above items must be checked very care fully to factory standards and not just given a casual inspection with the common expression Everything looks O K You can KNOW def
18. dpoint en Page 14 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Service Instructions for Model DLTX Carbureters Type A Cast Fuel Bowl Type B Stamped Fuel Bowl The following procedure for service of DLTX carbureter models is for a complete overhaul After removing carbureter from engine wash thoroughly with cleaning fluid such as gasoline to permit examination of external parts for damage For type carbureter being serviced see illustrations above Instructions apply to both types unless specified otherwise i Remove Bowl Retaining Nut Gasket and Nozzle Retaining Spring Separate Castings Remove Fuel Strainer Assembly and Gasket Type A Replace assembly if screen or threads are not in good condition 3 Remove Float Valve Seat and Gasket Type A Remove seat with Schebler Tool No 725A s Remove Float Lever Bear ing Screws and Float Lever Pin Type A Replace screws and pin if parts are worn 5 Remove Float and Lever Assembly amp Float Valve Type A Replace float valve and seat if valve is grooved or worn or seat damaged e Remove Float Valve Float Valve Seat amp Gasket Type B Replace Float Valve and Seat if valve is grooved or worn or seat damaged 7 Remove Load Adjusting Needle Replace needle if grooved or damaged 8 Remove Idle Adjus
19. drawn into the manifold As soon as the engine fires and runs the rich mixture must be rapidly reduced to prevent stalling This change in mixture is ac complished by the operator positioning the choke valve to provide the proper mixture However afew degrees movement of the choke valve 25 will make a big change in the mixture strength and to help reduce the sensitivity of the choke valve 25 position use is made of a spring loaded relief valve 26 in many applications This valve opens automatically with engine speed and load and eliminates a great deal of manipulation of the choke on the part of the operator When the engine has obtained normal oper ating temperature the choke valve 25 must be fully opened to assure maximum power and economy In addition extended use of the choke results in more gasoline being supplied to the engine than can be burned A large percentage of the unburned gasoline is lost through the ex haust system The remainder of the raw gasoline is forced between the pistons and cylinder walls washing away the protective oil film and increas ing engine wear and enters the crankcase where it dilutes the engine oil Any adjustments that are necessary on the carbureter should never be attempted until the engine has obtained its normal operating tem perature and the choke valve 25 has been placed in the wide open position Page 6 Marvel Schebler Products Division Borg Warner Corporation Decatur
20. e back suction economizer system to regulate the air pressure in the fuel bowl cham ber for proper fuel delivery to the engine The size of the plug is carefully established by engi neering tests and the specified size for a given carbureter model must always be used to assure the proper operation of the carbureter on the engine In some models a calibrated fixed orifice is machined in the throttle body casting in place of the economizer plug To provide additional economy in addition to the back suction economizer system the carbu reter provides for two adjusting needles the low speed or idle adjusting needle and the load ad justing needle These needles must not be inter changed The idle adjusting needle head is brass plated and the load needle cadmium plated gray color to distinguish A throttle lever stop spring Figure 1 is pro vided to prevent uneven running or hunting governor opening and closing when the load is released and the governor closes clear shut Turn the throttle stop screw against the throttle lever stop spring until the hunting is corrected and idling is satisfactory Normally there is 42 clearance between the throttle stop screw and the throttle lever stop spring at fast idle While there are many variations produced by combining the types and sizes into a specific ap plication all Model DLTX Carbureters incorpo rate the same engineering principles and are alike from a functional stan
21. for the next acceleration T_T Page 4 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Back Suction Economizer System THROTTLE The amount of fuel supplied to an engine is controlled by the size of the power jet the po sition of the power adjusting needle and the difference in air pressure between the fuel bowl chamber and the venturi However in many engines the mixture must be leaned out addi tionally during part throttle operation to obtain maximum economy To provide this leaner mixture Marvel Schebler Tractor and Industrial Carbureters make use of the Back Suction Economizer System With this method of meter ing fuel the air pressure in the fuel bowl chamber is regulated and controlled according to load conditions by a combination of bowl vent and economizer passages communicating with the throttle bore of the carbureter Through regulations of the air pressure in the fuel bowl chamber the fuel flow through the carbureter can be controlled to provide the prop er mixture proportions for the engine All the air that enters the fuel bowl chamber 9 must first pass through the air cleaner and the bowl vent 22 The size of the bowl vent 22 controls or limits the amount of air that can enter the fuel bowl chamber 9 The amount of air that is drawn out of the fuel bowl chamber 9 is controlled by the size of the economizer jet 23 the economizer orifice 24 and the posi
22. he throttle body casting To provide additional economy in addition to the back suction economizer system some carbu reters are provided with two adjusting needles the low speed or idle adjusting needle and the power or load adjusting needle However the power adjusting needle is not always required and for applications of this nature the fixed jet type carbureter is used in which the power jet controls the amount of fuel that is supplied to the engine There are two variations in carbureters hav ing the power adjusting needle commonly called the adjustable jet type carbureter In Figure 1 is shown these two arrangements The adjust ment of either type is accomplished in the same manner A large percentage of the Model TSX Carbu reters are provided with an idle adjusting needle which alters the fuel and air proportions of the mixture which enters ihe carbureter bore from the idle passage Figure 1 This is known as an FLOAT VALVE air adjusting idle needle The upper inset in Figure 1 shows an idle adjust ing needle which alters the amount of fuel and air mixture which enters the carbureter bore from the idle passage This is commonly known as a fuel ad justing idle needle It is important to remember in setting the idle mixture the air adjusting idle needle must be turned in or clockwise to enrich the idle mixture and the fuel adjusting idle needle must be turned out or counter clockwise to enrich the idle mixture
23. holes should only be cleaned with a cleaning fluid such as gasoline and air under pressure Never use drills or wires as a change in size of these small openings will change the entire calibration of the carbureter SSS Page 3 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Power Fuel Feed System Y LLG eee Qn POWER ADJUSTING NEEDLE SEAT 19 POWER ADJUSTING NEEDLE 18 With the throttle valve 6 in slow or just off slow idle position fuel rises up through the nozzle 14 and out the nozzle air bleeds 15 to fill the accelerating well 16 to approxi mately the height of the fuel level in the fuel bowl 1 As the engine speed is increased from the slow idle position the air flow through the venturi 17 is gradually increased and as the idle system begins to diminish the velocity through the venturi 17 is high enough to create a pres sure at the tip of the nozzle 14 slightly less than the pressure in the fuel bowl chamber 9 and the accelerating well 16 Fuel therefore feeds from the fuel bowl 1 through the open ing between the power load adjusting needle 18 and the power adjusting needle seat 19 through the power jet 20 and out the nozzle 14 to be discharged into the air stream at the THROTTLE VALVE 6 FUEL BOWL CHAMBER 9 venturi 17 At the same time the fuel that is stored in the accelerating well 16 is also forced
24. hrottle body and lower fuel bowl over floats taking precaution that venturi guides bodies into position or WBAuYW 33 Install Bowl Cover Screws and Lock Washers Tighten screws gradually until all are tight 34 Install Power Adjusting Needle Assembly Type A Set approximately one turn from seat for preliminary setting Instructions IDLE ADJUSTING NEEDLE AIR ADJUSTING To richen the idle mixture turn the idle adjusting needle to the right or clockwise IDLE ADJUSTING NEEDLE FUEL ADJUSTING To richen the idle mixture turn the idle adjusting needle to the left or counter clockwise POWER OR LOAD ADJUSTMENT TYPE B TYPE C With the engine running at governed speed under load turn power adjusting needle to the right or clockwise a little at a time until the power drops appreciably Then turn the needle to the left or counter clockwise until the engine picks up power and runs smoothly This will give an economical part throttle mixture and due to the economizer action the proper power mixture for full throttle operation Due to variations in temperature or fuels it may be necessary to richen up this mixture by backing out the power adjusting needle a small amount at a time until good acceleration is obtained NOTE Carbureters TSX 107 TSX 330 TSX 339 TSX 355 TSX 385 and TSX 398 use the fuel ad justing type idle needle All other Model TSX Carbureters use the air adjusting type idle
25. i nitely that the tractor is up to the standards set by the manufacturer POWER AND ECONOMY LOW Complaints are received from the field that the engine will not pull or develop its maximum horsepower or that it develops good power but uses far too much fuel Too often a service man will at once change the carbureter to correct these complaints but by so doing he may not be successful in overcoming the difficulty It must be clearly understood by all service men that when a new engine is designed and developed the management first decides what horsepower they want this engine to produce at a definite rated speed The engineering depart ment develops the new engine to pull the re quired horsepower In the design there are cer tain fixed dimensions that never change For instance the bore and stroke the displacement compression ratio diameter of valves lift of valves diameter of intake passage The carbu reter engineer works out the diameter of throttle bore venturi size and provides for means of adjusting and regulating the power fuel mixture ratio as well as the idle Now in service con sider that the compression ignition and timing have been checked and found to be 100 in this engine If the air intake temperature and the water temperature is held constant then the only variable we have that affects maximum horsepower is the fuel mixture ratio If compression ignition and timing which are variable are f
26. ination of external parts for damage For type carbureter being serviced see illustrations above Instructions apply to all types unless specified otherwise Remove Power Adjusting Needle Assembly Type B e Remove Bowl Cover Screws and Lock Washers Separate Castings r Remove Float Valve Bowl Gasket and Venturi If Valve is grooved or damaged replace Valve and Float Valve Seat 4 Remove Float Valve Seat and Gasket 5 Remove Economizer Jet NOTE Not required in all carbureters Check service parts list or repair kit of carbureter being serviced 6 Remove Idle Jet NOTE Not required in all carbureters Check service parts list or repair kit of carbureter being serviced Removing Idle Adjusting Needle and Spring Replace with new Needle if grooved or damaged s Remove Throttle Valve Screws Valve and Throttle Shaft and Lever Assembly Replace with new shaft and lever assembly if ex cessive looseness between shaft and throttle body Page 9 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A 5 Remove Throttle Shaft Packing Retainer and Packing Force out Retainer with small screwdriver or punch 10 Remove Main Nozzle and Gasket Type A Type B 11 Remove Power Jet Type A Type B 12 Remove Power Adjusting Needle Assembly Type C Carbureters not having adjustable needle re
27. irst properly checked by a service man and set to factory specifications very little difficulty will be experienced in ad justing the carbureter to give the maximum horsepower and economy A great deal has been said regarding the im portance of engine tune up and the reasons for service men being exact in their service work on engines The reasons why a carbureter may not Page 19 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A function properly when everything else has been checked and set to factory standards will now be covered With the present type carbureter construction used on Marvel Schebler tractor and industrial carbureters not very much can go wrong with the possible exception that it may foul with dirt There are only two places that are subject to wear the throttle shaft and bushings and the float valve and seat The wear on the throttle shaft and bushings and resultant air leak there from results in a lean idle and to compensate for the air leak more fuel must be turned on for idle Wear on the float valve and seat results in a high fuel level in the fuel bow and flooding trouble Both faults can be easily observed by the service man and corrected by replacing worn parts with new ones The proper function Page 20 ing of the carbureter is obtained by a series of holes drilled to exact size and location which do not wear or change location in service It mus
28. is U S A Float System A AS FLOAT VALVE SEAT 4 ZZ FLOAT AND LEVER 2 LLY LiL bdssis lille ANISS FUEL BOWL 1 The float system controls the level and supply of gasoline in the fuel bowl throughout the oper ating range of the engine When the fuel bowl 1 is empty the float and lever 2 and float valve 3 drop and fuel under pressure from the fuel pump or gravity feed is forced through the float valve seat 4 around the float valve 3 and into the fuel bowl 1 As the fuel in the bowl approaches the correct operating level it raises the float and lever 2 with enough force to raise the float valve and eut off the flow of fuel into the bowl As fuel feeds through the carbureter jets into the engine the fuel level 5 drops allowing additional fuel to enter the fuel bowl Under actual operating conditions the fuel level 5 and float and lever 2 automatically position themselves so that the inward flow of gasoline to the carbureter is equal to the out ward flow of gasoline to the engine As can readily be seen the float system under the most favorable of operating conditions is subjected to a certain amount of wear Under severe conditions or conditions that result in ex cessive vibrations being transmitted to the carbu reter float valve and float valve seat wear is accelerated ANAAAAAANRAAAAAAAARAAAR It should be an estab lished policy that when ever the carbureter
29. lodged between the float valve 3 and float valve seat 4 ee ee ee eee Page 2 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A The Idle System THROTTLE VALVE 6 SECONDARY IDLE ORIFICE 8 IDLE JET 11 IDLE FUEL PASSAGE 10 LL N The idle system controls the flow of fuel at idle speed and at slow speeds until the throttle is opened wide enough to allow the power fuel feed system to function When the throttle valve 6 is in the idle posi tion the edge of the valve is between the primary idle orifice 7 and the secondary idle orifice 8 With the valve in this position the air pres sure manifold vacuum at the primary idle orifice 7 is lower than the air pressure in the fuel bowl chamber 9 and fuel is forced from the fuel bowl 1 into the idle fuel passage 10 As the fuel travels through the idle fuel passage 10 it passes through the metering orifice of the idle jet 11 to the point where it is combined with air entering through the idle adjusting needle seat 12 The mixing of air with gasoline helps to atomize the fuel and this process is repeated at the secondary idle orifice 8 as the fuel travels through the idle fuel passage 10 As this rich mixture of fuel and air emerges from the primary idle orifice 7 it is reduced to cor rect proportions by the air which passes around PRIMARY IDLE ORIFICE 7 FUEL BOWL CHAMBER
30. move power jet 13 Remove Main Nozzle and Gasket Type C 14 Remove Retainer Plug and Gasoline Drain Strainer Strainer can only be re placed on carbureters hav ing a curled hair or felt type strainer Only re place when impossible to clean with gasoline and compressed air Porous metal type strainer can not be replaced Clean only 15 Remove Choke Valve Screws Valve Choke Shaft amp Lever Assembly Choke Return Spring and Choke Bracket 16 Remove Choke Shaft Packing Retainer ri and Packing MARVEL SCHEBLER Force out retainer with small screwdriver or punch ASSEMBLE 17 Install Throttle Shaft Packing and Retainer Assemble new retainer and packing on throttle shaft Insert shaft in carbureter and tap lightly until retainer is flush with casting face 18 Install Throttle Valve and Screws Install valve with angle identification mark facing flange face of carbureter Tap valve lightly to cen ter in throttle bore Tight en screws securely Before assembling carbureter clean castings channels and parts with carbureter cleaning fluid and air under pressure Make certain all small holes and channels are open and free from carbon and dirt Do not use wire or small drills to clean out small holes as a slight change in size of these holes will affect the carbureter operation To assure a successful overhaul always replace all worn or damaged parts and
31. mpression and good ignition before it can have good carburetion When the average person thinks of carbure tion they immediately think of the carbureter as a unit Carburetion is the combined function of the carbureter manifold valves piston and rings combustion chamber and cam shaft It can be readily seen that carburetion is a far deeper subject than consideration of the car bureter alone and expecting the carbureter to cure faulty ignition compression valves etc will only result in wasted time and effort on the part of the service man and added expense to the customer It must be remembered that the function of the carbureter does not extend beyond deliver ing the proper mixture of fuel and air to the manifold and the other factors which effect power and economy cannot be changed or cor rected by the carbureter Inability to understand all the factors that effect engine operation is the reason many service mechanics change from fac tory standards and attempt to improve on the engine set up by their own methods or stand ards All that any service mechanic should ever try to do is to make the particular engine he is working on as good as the manufacturer in tended it to be but he can make it a lot worse Far too many engines are running below their standard of performance in service today For the carbureter to accomplish its function it must be able to vary the mixture strength de pendent u
32. pon the engine demands It must supply a mixture strength that will allow the en gine to give maximum horsepower whenever the throttle is fully opened while at part throttle conditions it must lean out the mixture so that maximum economy can be obtained In addition it must have flexibility throughout the entire range of operating speeds from idle and part throttle to full power wide open throttle posi tion The carbureter must also have an acceler ating well with enough fuel capacity to start handling sudden maximum loads In other words the carbureter not only varies the volume of fuel and air that enters the engine but also varies the amount of fuel that goes in with a given amount of air in order to produce the proper mixture proportion for any condition under which the engine is operating at any time In order to understand the function and opera tion of the Marvel Schebler Tractor and Indus trial Carbureters it is well to consider the systems that make up each carbureter These systems are The Float System The Idle System The Power Fuel Feed System The Back Suction Economizer System and The Choke System A thorough knowledge of each system will help the service mechanic to quickly locate and correct legitimate carbureter complaints as well as to inspect repair and put back to standard any carbureter that requires an overhaul Page 1 Marvel Schebler Products Division Borg Warner Corporation Decatur Illino
33. r dirt All air entering the fuel bowl of the carbureter must first pass through the air cleaner The throttle shaft bear ings and the choke shaft bearings are sealed to eliminate dust and dirt entering at these points New throttle shaft bushings can be installed when the bearings have become worn The float mechanism is contained in a cast iron fuel bow Figure 1 on all DLTX models with the exception of Model DLT X 26 and Model DLTX 46 In these two carbrueters the float assembly is retained by the throttle body casting surrounded by a stamped metal fuel bowl All models have a fuel strainer to prevent dirt and foreign substance from entering the fuel Page 13 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Model DLTX Carbureter BOWL VENT BOWL DRAIN BOWL RETAINING NUT IDLE ADJUSTING NEEDLE IDLE PASSAGE Fig 2 Idle and Back Suction Economizer Systems bowl To service the fuel strainer in the cast iron fuel bowl first remove the sediment cup drain plug Figure 1 to permit any dirt to drain off Then remove the fuel strainer assembly and clean with gasoline and air under pressure Flush sediment cup by turning on fuel supply valve using a small brush to wash out any re maining dirt in cup Be careful not to damage or remove composition gasket on fuel strainer assembly Always replace any damaged gasket A calibrated economizer plug Figure 2 is used in th
34. rd start ing or erratic engine op eration The Model TSX carbu reter is completely seal ed against dust or dirt All air entering the fuel bowl of the carbureter must first pass through the air cleaner The throttle shaft bearings and choke shaft bear ings are sealed to elimi nate dust and dirt enter ing at these points The back suction econ omizer system Figure 2 is provided with a removable economizer jet The size of this jet has been carefully es tablished by engineer ing tests to provide the exact fuel requirements for maximum economy at part throttle opera tion Always use the economizer jet specified in the individual carbureter service parts list to assure proper engine operation On some carbu ECONOMIZER Le JET ECONOMIZER ORIFICE BOWL VENT Fig 2 Back Suction Economizer System Page 7 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Model TSX Carbureter ZA CHOKE VALVE 9 GASOLINE DRAIN STRAINER Fig 3 Float and Choke Systems reter models the proper fuel requirements are established without the use of an economizer jet and the fixed economizer orifice machined in the carbureter throttle body regulates the fuel sup plied to the engine In addition there are engine and carbureter combinations that do not require the back suction economizer system In these carbureters the economizer orifice has not been machined in t
35. t be realize that if the carbureter worked correctly at first when passed by the inspectors at the tractor factory it will always function the same provided these passages are all free from dirt On a carbureter complaint from the field the only thing a service man can do to the carbu reter is to disassemble it BE SURE that the passages are open and free from dirt that there is no wear on the throttle shaft and bushings that float valve and seat are O K that the float height is correct and that a good air tight seal exists around the bowl gasket If such carbureter service does not correct the complaints a com plete check of the engine must again be made Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Marvel Schebler Carbureter FLOAT SETTINGS To check the float setting the casting must be held in an inverted position so that the float lever is in contact with the float valve and the float valve seated Factory Carbureter Model Setting Where to Measure DLTX 26 and 46 ee ee From the bottom of the nozzle boss to the nearest surface of the float DETR T1 Tey CB ieceri 5 Sete ere et From the bowl gasket to the nearest surface of the float All other DLTX except duals Cork or Metal Float Ma TEN From the bowl gasket to the nearest surface of the float Duplex DLT Xaus SG ikon aalis From bowl gasket seat in casting to bottom of float a E L E ai to sb
36. ting Needle Replace needle if grooved or damaged Page 15 Marvel Schebler Products Division Borg Warner Corporation Decatur Illinois U S A Service Instructions for 5 Remove Throttle Valve Screws Valve amp Throttle Shaft amp Lever Assembly NOTE On some models it is necessary to first re move throttle lever from shaft before throttle valve can be removed Replace throttle shaft if worn 10 Remove Choke Valve Screws and Valve Do not remove choke shaft 11 Remove Nozzle Insert flat end of Schebler Tool No 2599 under choke shaft and force nozzle down as far as possible 11A Insert bent end of tool over choke shaft and force nozzle out 12 Remove Choke Shaft and Lever Assembly Replace shaft and lever assembly if shaft is worn 12A Remove Choke Shaft and Lever Assembly Replace shaft and lever assembly if shaft is worn Model DLTX Carbureters Remove all Channel Plugs Throttle Shaft Bushing Repair Procedure for replacing worn throttle shaft bush ings 14 Remove Upper Throttle Shaft Bushing Insert Schebler Tool No 2603 amp drive bushing out jit NOTE On Models DLTX 26 and DLTX 46 remove gt bushing with tool No M 130 15 Remove Lower Shaft Bushing Insert Schebler Tool No 2603 through upper throttle shaft bushing boss arid drive bushing out
37. tion of the throttle valve 6 as its position determines the manifold vacuum or suction on the econo mizer orifice 24 As the throttle valve 6 is opened from the fast idle position the economizer orifice 24 is gradually ex posed to manifold suction and air flows from the fuel bowl chamber 9 through the economizer jet 23 and out the econo mizer orifice 24 This air must be re placed by air entering through the bowl vent 22 but as the size of the bowl vent 22 restricts the amount of air that can enter the resultant pressure in the fuel bowl chamber 9 will be lowered reduc ing the difference in air pressure between the nozzle 14 and the fuel bowl chamber 9 The flow of fuel will therefore be re tarded so that the exact economy mixture ratio will be delivered to the engine at this particular throttle opening Opening the throttle valve 6 further exposes the entire economizer orifice 24 to manifold suction resulting in additional air being removed from the fuel bowl chamber 9 again leaning out the mixture ratio to the correct proportions for this new throttle position After the econo mizer orifice 24 is fully exposed to manifold suction the amount of air that is drawn out of the fuel bowl chamber 9 is controlled by the manifold vacuum or suction at any given throttle valve 6 position and as this suction decreases as the throttle approaches wide open position less air is drawn out of the fuel bowl ch
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