CARBURETOR - Holley Performance Products
Contents
1. CARBURETOR P N 0 804575 0 80457SA amp 0 80458SA electric choke P N 0 1850C 0 1850S amp 0 1850SA manual choke INSTALLATION TUNING AND ADJUSTMENT MANUAL 199R7948 5 NOTE These instructions must be read and fully understood before beginning installation this manual is not fully understood installation should not be attempted Failure to follow these instructions including the pictures may result in subsequent system failure TABLE OF CONTENTS INTRODUCTION ssc 3 ee a 3 E EE EE ee 3 ELECTRIC CHOKE MODELS anena s ewe a a a a A aaa a 6 MANUAL CROKE MODELS a aaa aaa aa aa a 6 INSTALLATION NOTES cccsccssecssscsesecsesssscsesecsecscscsesscsesseacsesscscesuacsessrsestacsesecsessracsesausesacacsecess 7 CHRYSLER APPEIGA TIONS a a aaa a aa at 7 FORD 2 7 8 CHOKE ADJUSTMENT cccssessccessssecssscsssecsesesscsesscsesscscsessuscsasacsssuacssscsessuacsssusessvacsesansesanaess 9 FUEL LEVEL FLOAT LEVEL FOR ADJUSTABLE NEEDLE amp SEAT EQUIPPED BOWLS 10 IDLE MIXTURE NEEDLES csccscecssccsessssecssscsesecsesssecsesscsesssacsessuscesracsessuacessacsesatacsesausesscaess 12 VACUUM OPERATED SECONDARY THROTTLES ssssses2. applications equipped with V 6 and V 8 engines It is designed for use on square flange intake manifolds Carburetor adapters are not recommended to adapt to spread bore intake manifolds since adapters may have an adverse affect on cylinder to cylinder distribution and ultimately total engine performance However some manifolds may be universal such as Weiand 8004 Please check with Holley s Technical Service Department if you have any questions REMOVAL 1 Remove the air cleaner exercising care to carefully detach any vacuum lines from the air cleaner and marking them so they can be reassembled to the air cleaner in the same manner 2 Remove the existing carburetor by the following procedure A Carefully disconnect the fuel line WARNING Carefully protect the open end of the fuel lines so that no foreign particles can enter Wrap the end of the fuel line with a clean lint free cloth Disconnect and mark all vacuum lines and wiring if any to the carburetor Disconnect the PCV hose Disconnect the choke rod or heat tubes if equipped Disconnect and remove the throttle linkage and automatic kickdown linkage Save all retaining clips Unbolt and remove the carburetor from the manifold 3 Ifthe intake manifold is being changed at this time install the new manifold according to the manifold s directions Since we are not familiar with all manifold instructions Holley cannot a
3. in the neutral Remove the sight plug to confirm your setting A slight trickle should be seen at the threads Adjust if necessary Replace the sight plug and tighten FOR 0 80458SA ONLY NOTE Do not try to remove the sight glasses It takes special tools to install these and it is not recommended that they be removed Primary and secondary float adjustments are set at the factory but variations in fuel pressure could cause a change in these settings To aid in adjustment of the float levels clear sight glasses are installed from the factory The following procedure shows how to make these adjustments 1 Start the vehicle 2 Observe the sight glass for the fuel level If none is seen the level is too low If it is higher than the middle of the sight window it is too high NOTE A properly set float level will have the fuel level located at the middle or slightly below the middle of the sight window as shown by the line in Figure 11 Float Level Lock Screw Float Level Adjusting Nut Fuel Level N Figure 11 3 To adjust shut down the engine 4 Loosen the lock screw on top of the fuel bowl just enough to allow you to turn the adjusting nut Hold the screw in position with the screwdriver 5 Using a 5 8 wrench turn the adjusting nut in the appropriate direction Clockwise to lower float and counterclockwise to raise float NOTE Many customers attempt to adjust the float level down by turning the adjusting nut cl
4. open and recheck the float level 11 IDLE MIXTURE NEEDLES Idle mixture needles control the air fuel mixture at idle These have been preset at the factory and SHOULD NOT need any adjustments However if you feel that adjustment is necessary you can use the following procedure to do so When tuning the idle mixture you re actually tuning for the best manifold vacuum Idle mixture needles are found on the primary metering blocks If you change one idle mixture needle you must change the other idle mixture needle by the same amount Here are the proper steps for setting the idle mixture needles 1 Attach the vacuum gauge to a manifold vacuum port on the throttle body Figure 3 2 Adjust each idle mixture screw Figures 12 amp 13 1 8 turn at a time alternating between each screw Turn them equally until you achieve the highest possible vacuum reading without adjusting the curb idle speed screw Turn screws in to lean the mixture Turn them out to richen the mixture Idle Mixture Screw Figure 12 Figure 13 Now that the idle mixture is set it may be necessary to go back and reset the idle speed using the curb idle speed screw as shown in Figure 14 4 Ifa vacuum gauge is not available use a tachometer to obtain the highest RPM Curb Idle Speed Screw Figure 14 ROUGH IDLE AND VACUUM LEAKS If a rough idle persists after the engine has been started and the mixture screws adjusted check for manifold vacuum leaks
5. you in fine tuning adjustments Electric Choke 1 You can control the choke operation by rotating the choke cap If the choke comes off too soon loosen the three screws and rotate the cap counterclockwise one notch at a time until the choke operation is satisfactory If the choke comes off too late rotate the cap clockwise one notch at a time until the choke operation is satisfactory The choke setting from the factory is on index or at center position After making the final adjustments start the engine and make sure the choke plate opens completely A A choke that comes off too soon could exhibit one or more of the following symptoms stalling surging backfiring stumbles or poor vehicle driveability when the vehicle is cold A choke that comes off too late could exhibit one or more of the following symptoms black smoke from the tail pipe poor driveability when cold poor gas mileage misses or rough idle Manual and Electric Chokes 2 Ifthe fast idle RPM is too low or too high for your preferences SHUT DOWN THE ENGINE Advance the throttle to wide open exposing the fast idle set screw below the choke housing See Figure 7 3 Using a 1 4 open end wrench turn the screw clockwise to increase the RPM or counterclockwise to decrease the RPM The factory setting should give you a 1500 1600 RPM fast idle speed NOTE All vacuum ports must be plugged at this time Fast Idle Speed Screw Figure 7 FUEL LEVEL Flo
6. Lockout Screw Figure 6 Ford applications GM APPLICATIONS WARNING If you are using this carburetor with a GM overdrive transmission TH700R4 or a TH200R4 you must use a transmission kickdown cable bracket Holley P N 20 95 and geometry corrector Holley P N 20 121 Otherwise SEVERE transmission damage WILL result Depending on your accelerator bracket you will need one of the following throttle studs Holley P N 20 2 20 38 or 20 40 This carburetor is not designed to work with ANY other automatic overdrive transmissions 1 Remove the throttle cable ball and automatic transmission kickdown stud if any from the original carburetor and mount these in similar locations on the Holley throttle lever If the original throttle cable is too large a new throttle ball or stud is needed Holley P N 20 2 or 20 38 NOTE For proper adjustment of the GM automatic kickdown linkage refer to the appropriate GM service manual for your application WARNING On automatic transmission vehicles only install the transmission kickdown adjustment screw and black retaining clip as correctly indicated Failure to attend to this detail may result in a sticking wide open throttle or dangerous uncontrolled engine speed CHOKE ADJUSTMENT IMPORTANT Your Holley carburetor has been factory wet flowed and calibrated The out of the box settings should be very close for all adjustments The following tuning section is included ONLY to aid
7. These could result from unplugged vacuum fittings or a carburetor flange gasket that was torn during installation Recheck for proper attachment of all vacuum lines and check the lines for cracks If the manifold was changed a manifold vacuum leak could occur at the cylinder head manifold surface due to damaged gaskets improper torquing Frequently manifold vacuum leaks occur from the valley side of the manifold These are very difficult to detect unless a discernible whistle can be heard NOTE In most cases when rough idle occurs after a carburetor manifold change they result from manifold vacuum leaks similar to those described above Assuring a proper manifold installation rather than assuming the carburetor is not functioning properly will ultimately save time 12 VACUUM OPERATED SECONDARY THROTTLES Many people have the misconception that opening the secondary throttles sooner will provide increased performance and quicker drag strip times Others think they must feel a kick when the secondaries engage Still others believe that they should disconnect the vacuum diaphragm and make the secondaries open mechanically Before going any further lets discuss these points in a reverse order First if we could make our vacuum operated secondary carburetors perform better by opening the secondaries mechanically it would be to our advantage to do so since all that vacuum actuating hardware is expensive and requires much time and money
8. ase in altitude 3 Holley jets are broached flowed and stamped according to flow rate NEVER drill jets as this seriously alters flow characteristics Stamped numbers are reference numbers and DO NOT indicate drill size 4 In most cases it will be unnecessary to increase jet size more than four numbers greater than out of the box jetting Exceptions could arise when the carburetor is mounted on a very large volume plenum ram manifold 5 Spark plugs provide the best indication of proper jetting Consult an ignition manual for proper reading of spark plugs POWER VALVES The number stamped a power valve such as 65 indicates the manifold vacuum below which the power valve is operational In this case all manifold vacuums below 6 5 Hg the power valve is operating Generally a 65 power valve is sufficient for most high performance applications that have a manifold vacuum of 12 Hg or higher However some problems can result with radically cammed machines equipped with automatic transmissions These vehicles often idle at 2000 rom approx 6 0 Hg At this point the main nozzles are starting to feed and richen the mixture supplied by the power valve and the engine will probably load up To correct this problem install a 45 or 35 power valve If the engine has a manifold vacuum of 12 Hg or less a good way to determine power valve size is take the manifold vacuum at idle and divide that number by two The answer is t
9. at Level for Adjustable Needle amp Seat Equipped Bowls 0 80457SA amp 0 1850SA eE j Fuel level at of site plug Figure 8 Figure 9 The float s controls the fuel delivery however if the float s are not properly adjusted a fuel starvation or a flooding affect could result This operation is difficult to do accurately on a rough idling vehicle 1 10 Mechanical fuel pump remove coil wire and crank engine over for 10 seconds to allow fuel bowls to fill This procedure can prevent a power valve blow out Reconnect coil wire when finished Electric fuel pumps let the fuel bowls fill in stages by turning the ignition on and then off let fuel pump run for a few seconds at a time This procedure can prevent the needle from being forced up at an angle not allowing the needle to seat properly Remove the sight plug from the fuel bowl and start the vehicle Loosen the lock screw at the top of the assembly Turn the adjusting nut while holding the screw in place until the fuel level is at the bottom of the sight plug hole even with the threads A slight trickle can be seen at the threads Turn the adjusting nut clockwise to lower the fuel level and counter clockwise to raise the fuel level Adjusting Nut Figure 10 Tighten the lock screw while holding the adjustment nut Replace the sight plug and finger tighten Flush the fuel bowl by revving the engine a few times with the transmission
10. ave an assistant slowly press the accelerator pedal to the floor while you watch the throttle for any sticking or binding Correct any sticking or binding conditions before proceeding Also ensure that you are reaching full throttle Many performance problems are traced to partial throttle openings from improperly adjusted linkage Secondaries will not open mechanically during this procedure Fuel Bowl Vents List and Prod Date Timed Spark Vacuum Source to distributor vaccum advance Primary Secondary Fuel Bowl Fuel Bowl Idle Mixture Screw one on each side of bowl Power Brake or PCV Vacuum Port Choke Thermostat Diaphragm Positive Choke Ts Negative Choke Terminal must 9 Terminal must have 12 be grounded Figure 2a Choke Cable Clamp Choke Cable Lock Screw Choke Actuation Lever Figure 2b Manual choke parts 0 1850 shown 6 Reconnect the appropriate vacuum hoses to the carburetor noting the correct fitting from Figure 2a and Figure 3 Replace any cracked or dry rotted hoses at this time to prevent any vacuum leaks The full manifold vacuum source in the front of the throttle body provides vacuum for proper operation of the air cleaner the pump diverter valve if equipped AC Cruise and or the temperature sensing valve If vacuum for more than one component is needed use small plastic vacuum available at most automotive stores B The timed spa
11. buretor should be inspected periodically to assure no fuel leakage and to ensure the soundness of the hoses Today s clean emissions engines provide higher temperatures in the engine compartment These high temperatures promote faster aging of non metallic materials Hoses that exhibit surface cracks when bent to 180 should be replaced The presence of liquid fuel demands tightening of fittings hose replacement and retorquing of the fuel system component flange nuts Periodically check the torque on the fuel bowl screws to 25 30 in lbs to assure proper fuel metering GENERAL Some very important factors to optimize efficiency and performance include Correct engine timing correct spark plug gap and heat range ignition components in good working order and correct operation of exhaust heat valve WARNING On automatic transmission vehicles only install the transmission kickdown adjustment screw and black retaining clip as correctly indicated Failure to attend to this detail may result in a sticking wide open throttle or dangerous uncontrolled engine speed INSTALLATION NOTES CHRYSLER APPLICATIONS WARNING This carburetor is not designed for use with any Chrysler automatic overdrive transmission SEVERE transmission damage may result from improper application use 1 Unless you are replacing an existing Holley carburetor which already has a lever extension arm you may need to purchase and install a throttle lever extension Hol
12. ccept responsibility for their validity INSTALLATION 1 Install the carburetor mounting studs not provided the proper location on the intake manifold carburetor flange 2 Place the new carburetor flange gasket provided with the carburetor in the proper position on the intake manifold 3 Place the carburetor on top of the flange gasket on the manifold Install the hold down nuts and snug down progressively in a crisscross pattern 60 80 in lbs as shown in Figure 1 WARNING Overtightening may result in a warped or cracked carburetor throttle body 4 Before connecting the linkage operate the throttle lever to assure the correct travel no sticking or binding by opening to wide open throttle and back to closed throttle several times Correct any sticking or binding conditions before proceeding WARNING Any sticking binding or other interference in the throttle linkage could result in uncontrolled engine speed This could result in engine damage or personal injury 5 Reconnect the throttle and transmission kickdown linkage and throttle return spring Holley P N 20 89 Operate the carburetor throttle lever by hand to assure the correct travel no sticking or binding by opening to wide open throttle and back to closed throttle several times Correct any sticking or binding conditions before proceeding ENGINE Figure 1 Carburetor torque sequence all Holley carburetors NOTE With the engine turned off h
13. egard all references to the check ball as yours does not use a check ball 6 Change the spring Make sure that the new spring seats on the stud cast into the underside of the cover The stiffer the spring the later the secondaries will open 7 When reassembling secondary diaphragm parts exercise care to properly align the vacuum passage in the casting with the cut out in the rubber diaphragm and make sure the check ball is in place DO NOT pinch or tear the rubber diaphragm TIP To make reassembling the diaphragm easier push the diaphragm arm into the housing and form the diaphragm into a mushroom shape Figure 19 Then position the diaphragm over the bolt holes and vacuum port Hold the diaphragm in that position with your fingers while inserting the spring cover and bolts to avoid disturbing the position of the diaphragm 8 Make sure the cork gasket in the secondary diaphragm housing mates with the main body casting and reassemble the housing and choke to the main body 9 Reinstall the air cleaner and test drive the vehicle CORRECT 14 JETTING MAIN JETS Due to varied applications that a universal performance carburetor will work with a few tips on jetting are provided to help you understand their purpose 1 Out of the box jetting is extremely close for most applications 2 Carburetors are calibrated at 70 at sea level Decrease the jet size primary and secondary one number for every 2000 ft incre
14. ely reduced by the drain imposed by the choke cap Suitable ignition activated 12 volt sources are most electrical relays as well as the leads to accessories such as windshield wipers DO NOT connect this wire to the original equipment O E electric choke source This may not be a 12V source B Check the voltage source with a volt ohm meter to assure proper voltage and choke operation Provision of a good ground and 12 volt source that can supply enough current to the choke cap is essential for proper choke operation MANUAL CHOKE MODELS A Connect the choke control cable Holley P N 45 228 to the choke actuation lever and lock in place with the choke cable lock screw B Mount the outer sleeve to the cable clamp C Actuate the choke cable through its full range of motion to ensure full choke operation Adjust as necessary 10 Start the engine and check the fuel lines and inlet fitting for possible leaks NOTE The recommended fuel pressure is 5 7 psi Use an adjustable fuel pressure regulator Holley P N 12 803 if it is higher than 7 psi 11 Recheck to assure all existing vacuum hoses are attached properly Plug any fittings not used 12 With the engine at operating temperature set the idle speed to the manufacturer s specifications see page 10 for idle adjustment 13 Shut off the engine and readjust the throttle operated transmission linkage if necessary On installations that have a kickdown actuating switch on the pas
15. esesscsesesscsesesscsessserscsersracsesuacsesarers 13 VACUUM OPERATED SECONDARY TUNING2E cessscecessececessesesseseceesesessrsesescsessesessesesucaeseees 13 ET TING JETS E E E 15 POV Sse 15 CARBURETOR SPECIFICATIONS 15 INTRODUCTION CONGRATULATIONS on your Holley carburetor purchase We feel that you have purchased the finest performance carburetor manufactured today Should you need information or parts assistance please contact our Technical Service Department at 1 270 781 9741 Monday through Friday 8 a m to 5 p m CST Please have the part number of the product you purchased on hand when you call To preserve the warranty these instructions must be read and followed thoroughly before and during installation ATTENTION The information in this manual covers carburetor models 0 804575 0 80457SA 0 80458SA 0 1850 0 1850S and 0 1850SA For most pictures the 0 80457S carburetor equipped with electric choke is shown the illustrations in this manual NOTE The 0 804575 0 1850C and 0 1850S carburetors are 50 state emission legal replacement carburetors for 1965 69 V 8 applications In California those vehicles must have been originally equipped with a four barrel carburetor These carburetors have been designed and calibrated as a universal replacement carburetor for passenger cars and light truck
16. he power valve size This will provide idling and proper fuel flow under wide open throttle conditions when manifold vacuums seldom rise above 1 Hg CARBURETOR SPECIFICATIONS PRIMARY SECONDARY PUMP PRIMARY SECONDARY CARBURETOR METERING METERING DISCHARGE POWER DIAPHRAGM NOZZLE VALVE SPRING 0 804575 34R9716 6 0 031 0 1850C 0 1850S_ 15 Holley Performance Products Inc 1801 Russellville Rd Bowling Green KY 42101 Toll Free Technical Service 1 866 464 6553 Technical Service 1 270 781 9741 Fax 1 270 781 9772 For online help please refer to our website www holley com 2000 Holley Performance Products Inc All rights reserved 199R7948 5 Revision Date 4 1 13 16
17. les enter the fuel bowl after the new carburetor installation Remove the fuel line at the pump and blow the line clean with compressed air DO NOT use the procedure where the coil wire is disconnected the engine cranked for a few revolutions and the fuel collected in a container This procedure is unsafe because sparking can occur either at the coil or at the distributor end of the coil wire and ignite any fuel spilled in the engine compartment CAUTION The use of a quality in line fuel filter such as Holley P N 162 523 is mandatory as a safeguard against possible flooding which could result from unfiltered particles becoming lodged between the fuel inlet needle and its seat This can result in fire if a spark is present or backfire occurs in the engine compartment Air cleaner filter elements should be blown clean with compressed air at 6 000 miles and replaced at 12 000 miles to assure maximum protection Now would be the perfect time to upgrade to a Holley Powershot air filter Holley P N 120 146 ELECTRIC CHOKE MODELS A Connect the electric choke lead Supplied to the positive terminal of the choke cap The other end must be connected to a good ignition activated 12 volt source Hookup of this wire is not optional WARNING Connecting the choke cap to the ignition or ignition coil could result in unacceptable choke operation poor fuel economy and possible engine misfiring since the voltage delivered to the spark plugs will be sever
18. ley P N 20 7 on the carburetor Remove the throttle stud and nut from the original carburetor You can purchase a new stud from your Holley dealer Holley P N 20 67 Install the stud in the throttle extension lever Figure 4 Throttle Stud P N 20 67 Throttle Lever Extension P N 20 7 Figure 4 Chrysler applications FORD APPLICATIONS WARNING This carburetor is not designed for use with any Ford automatic overdrive transmission SEVERE transmission damage may result from improper application use NOTE Unless replacing an existing Holley Carburetor you may need to purchase Holley P N 20 91 spring and perch kit for Ford automatic transmissions 1 Install the throttle ball lockwasher and retaining nut to the carburetor throttle lever in the same position as the existing carburetor 2 Insert the transmission kickdown screw with the retaining clip and lock nut on the transmission kickdown lever Figure 5 This assembly must be installed according to the detailed drawing Figure 5 e oe Transmission Kickdown Adjusting Screw Retainer Spring Perch amp Lock Nut Throttle Lever Stop Transmission Kickdown Lever Transmission Kickdown Transmission Kickdown Spring Adjusting Screw Figure 5 Ford applications 3 Remove the lock out screw from the kickdown lever Figure 6 4 Install the transmission kickdown spring between the transmission kickdown lever and spring perch Figure 5
19. ockwise only to see the fuel level rise through the sight glass This is due to the float being pushed down into the fuel therefore displacing the fuel to a higher level You will find it easier to adjust the float levels if you rev the engine slightly between adjustments to evacuate the fuel Turn the adjusting nut in increments of 1 4 of a rotation Retighten the lock screw N Restart the vehicle and observe the sight window 9 Repeat steps 1 through 8 as necessary SECONDARY FLOAT LEVELS Very little fuel is drawn out of the secondary fuel bowls during idle operation This makes it a little tricky to set the proper float level with the sight glasses Many customers attempt to adjust the rear float level down by turning the adjusting nut clockwise only to see the fuel level rise through the sight glass This is due to the float being pushed down into the fuel therefore displacing the fuel to a higher level You will find it easier to adjust the float levels if you rev the engine slightly by opening the secondaries between adjustments This can be easily done by pushing upward on the secondary diaphragm stem or by rolling the secondary throttle shaft linkage forward on the driver s side of the vehicle This will use fuel from the secondary bowl at a much faster rate allowing the float level to seek the adjustment point that you have set Once the floats have been set with this procedure drive the vehicle making sure the secondaries
20. probably open too soon Secondaries should open only when the engine is under a load DO NOT clip or trim a spring in an effort to make a spring lighter so that the secondaries will open sooner Strange as it may seem clipping springs actually increases spring rate and will delay opening So in order to tune the secondaries follow the steps below A secondary spring kit is available from your local Holley retailer Holley P N 20 13 VACUUM OPERATED SECONDARY TUNING NOTE The Holley Quick Change Diaphragm Housing Cover makes swapping secondary springs a matter of loosening two screws It is available under P N 20 59 1 Remove the choke cap electric choke and choke housing manual and electric choke to gain access to the third screw retaining the vacuum diaphragm to the main body Figure 15 2 Remove three screws attaching secondary vacuum diaphragm to the main body Figure 16 Figure 15 Figure 16 3 Remove the clip retaining the diaphragm plunger to the secondary throttle lever using a small flat blade screwdriver Figure 17 13 VACUUM PASSAGE CORK GASKET WITH CHECK BALL OR BRASS RESTRICTION awe 3 Ds Figure 17 Figure 18 4 Remove the four screws securing diaphragm cover 5 Gently remove the cover Take care as not to tear the diaphragm or loose the check ball Figure 18 NOTE Your secondary housing may have a brass restriction inserted where the check ball should be If that is the case please disr
21. rk fitting the choke side of the primary metering block provides vacuum for the operation of the distributor vacuum advance Connect the hose to the distributor spark delay valve and or temperature sensing valve as originally connected Again use 5 as necessary If any questions arise about the hose connections consult the proper service manual C Plug any vacuum source not used The Choke Fresh Air Intake Hose is not drilled so no plug is needed 7 Connect the PCV hose to the PCV fitting in the carburetor base plate 8 Connect the power brake and or PCV hose to the fitting as shown in Figure 3 Full Manifold Vacuum Port Power Brake or PCV Full Manifold Vacuum Port Figure 3 9 In some cases the existing fuel line will have to be cut and connected to a dual feed fuel line with a length of rubber fuel hose and a clamp WARNING During the fuel line installation DO NOT allow any foreign particles to enter the fuel lines which could then cause flooding and may result in a fire WARNING Keep the fuel line away from the EGR valve if equipped on the intake manifold If installation requires cutting the metal fuel line cut the fuel line with a good tube cutter This will minimize the chance of producing metal chip particles If a hacksaw must be used then metal chips must be removed WARNING In all cases where the fuel line has been cut it is essential that it be clean to insure that no metal partic
22. senger s side of the firewall it might be necessary to readjust it according to the manufacturer s service manual FORD APPLICATIONS WITH AUTOMATIC TRANSMISSIONS With the engine off push the transmission kickdown rod rearward until it stops and hold it in position Push the throttle lever rearward to its wide open throttle position and adjust the transmission kickdown screw to come in contact with the transmission kickdown lever tang WARNING With the engine off recheck the assembled linkage for sticking and or proper return to the idle position 14 Place the air cleaner gasket Supplied on the sealing flange and install the air cleaner 15 With some air cleaner configurations it may be necessary to use an air cleaner spacer to provide adequate clearance between the carburetor and the air cleaner Holley offers such a spacer Holley P N 17 13 Depending on the overall height obtain the proper length 1 4 x 20 stud and install in the carburetor airhorn Close the hood slowly to ensure adequate clearance between the air cleaner stud and the hood WARNING Inadequate clearance between the air cleaner and the throttle lever could result in throttle sticking and uncontrolled engine speed Check the clearance between the throttle lever and air cleaner for proper operation Check the clearance between the air cleaner and the hood before closing the hood completely MAINTENANCE WARNING Fuel system components including fuel lines and the car
23. to calibrate Mechanical secondary carburetors all utilize a secondary pump shot to prevent bogging when the secondaries are opened Secondly those who feel a kick when the secondaries engage are actually feeling a flat spot during initial acceleration because the secondaries have already begun to open and have weakened the fuel delivery signal to the primary boosters The engine is struggling to increase speed and what they actually feel are the secondary nozzles crashing in as the engine finally reaches the speed where it provides the proper fuel delivery signal to primary and secondary venturi Third opening the secondaries early causes the situation described above The secondaries must not open until the engine requires the additional air This allows torque to increase along the peak torque curve Performance is compromised less by holding the secondaries closed a little longer than by opening them a little too soon If the opening rate of the vacuum operated secondaries is properly calibrated there should not be a kick only a smooth increase in power should be felt In general heavier cars require stiffer secondary diaphragm springs than light cars Air cleaner configuration and restriction plays an important part in spring selection also so be sure to use your air cleaner when evaluating your vehicles performance after each change DO NOT expect to wing the throttle and see the secondaries begin to open If they do they will
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