AutoZone 1995 Chevrolet Corvette 5.7L SFI OHV 8cyl | Repair Guides | Fuel System | Carbureted Fuel System | Carburetor | AutoZone.com

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    Ford Mid-Size Cars 1971-1985 Repair Guide

    Carburetor

    Print

    See Figures 1 through 11



    Click image to see an enlarged view

    Fig. Fig. 1: Autolite 1101-V carburetor



    Click image to see an enlarged view

    Fig. Fig. 2: Carter YF 1V carburetor



    Click image to see an enlarged view

    Fig. Fig. 3: Motorcraft 42 2V carburetor



    Click image to see an enlarged view

    Fig. Fig. 4: Autolite 4100 4V carburetor



    Click image to see an enlarged view

    Fig. Fig. 5: Autolite/Motorcraft 4300 4V carburetor



    Click image to see an enlarged view

    Fig. Fig. 6: Motorcraft 4350 4V carburetor



    Click image to see an enlarged view

    Fig. Fig. 7: Motorcraft 5200 carburetor



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    Fig. Fig. 8: Holley 4150 carburetor



    Click image to see an enlarged view

    Fig. Fig. 9: Holley 1933 carburetor



    Click image to see an enlarged view

    Fig. Fig. 10: Rochester Quadrajet carburetor



    Click image to see an enlarged view

    Fig. Fig. 11: Carter Thermo-Quad carburetor

    THROTTLE SOLENOID (ANTI-DIESELING SOLENOID) TEST



    Most models are equipped with a throttle solenoid positioner. The purpose of a throttle solenoid is to prevent the engine from running on (dieseling) after the ignition is turned OFF . Dieseling is a common occurrence with many cars using emission control systems that require a leaner fuel mixture, a higher operating temperature, and a higher curb idle speed. The throttle solenoid prevents run-on and dieseling by closing the throttle plate(s) after the key is switched to OFF , thereby shutting off the air and gas to the overheated combustion chamber.

    1. Turn the ignition key ON and open the throttle. The solenoid plunger should extend (solenoid energize.)
    2.  
    3. Turn the ignition OFF . The plunger should retract, allowing the throttle to close.
    4.  

    With the anti-dieseling solenoid de-energized, the carburetor idle speed adjusting screw must make contact with the throttle shaft to prevent the throttle plates from jamming in the throttle bore when the engine is turned OFF.

    1. If the solenoid is functioning properly and the engine is still dieseling, check for one of the following:
      1. High idle or engine shut off speed.
      2.  
      3. Engine timing not set to specification.
      4.  
      5. Binding throttle linkage.
      6.  
      7. Too low an octane fuel being used.
      8.  

    2.  
    3. Correct any of these problems as necessary.
    4.  
    5. If the solenoid fails to function as outlined, disconnect the solenoid leads. The solenoid should de-energize. If it does not, it is jammed and must be replaced.
    6.  
    7. Connect the solenoid to a 12 volt power source and to ground. Open the throttle so that the plunger can extend. If it does not, the solenoid is defective.
    8.  
    9. If the solenoid is functioning correctly and no other source of trouble can be found, the fault probably lies in the wiring between the solenoid and the ignition switch or in the ignition switch itself. Remember to reconnect the solenoid when finished testing.
    10.  

    REMOVAL & INSTALLATION



    Prior to removing any wire harness, vacuum line or cable, properly mark or tag the item.

    Motorcraft 42

    On vehicles with an automatic transmission, the transmission kickdown lever or the throttle valve lever must be adjusted whenever the carburetor assembly is removed for service or replacement.

    1. Remove the air cleaner assembly.
    2.  
    3. Disconnect the throttle cable from the throttle lever.
    4.  
    5. Unfasten all vacuum lines, emission hoses, the fuel line, electrical connection and choke heat tube at the carburetor.
    6.  
    7. Remove the carburetor retaining nuts. Lift off the carburetor carefully, taking care not to spill any fuel. Remove the carburetor mounting gasket and discard it. Remove the carburetor mounting spacer, if so equipped, from the intake manifold. To install:
    8.  
    9. Prior to installation, clean the gasket mounting surfaces of the intake manifold, spacer (if so equipped), and carburetor. When using a spacer, use two new gaskets, sandwiching the spacer between the gaskets. If a spacer is not used, only one new carburetor mounting gasket is required.
    10.  
    11. Position and connect the choke heat tube.
    12.  
    13. Install the spark and EGR port vacuum lines, if so equipped, before bolting the carburetor in place.
    14.  
    15. Place the new gasket(s) and spacer (if so equipped) on the carburetor mounting studs. Position the carburetor on top of the gasket and hand-tighten the retaining nuts. Then tighten the nuts in a crisscross pattern to 14-16 ft. lbs. (18-2 Nm).
    16.  
    17. Connect the fuel line, throttle cable, transmission linkage, emission hoses and vacuum lines.
    18.  
    19. Install the air cleaner assembly.
    20.  
    21. Adjust the engine idle speed and mixture settings, if necessary, as outlined in Engine Performance and Tune-Up . Be sure that the accelerator pump rod is set in the specified hole. (Refer to the Carburetor Specifications chart, later in this section.)
    22.  

    Carter YFA
    1. Remove the air cleaner assembly.
    2.  
    3. Disconnect the throttle cable or rod at the throttle lever.
    4.  
    5. Disconnect the appropriate vacuum lines.
    6.  
    7. Unfasten the fuel bowl vent hose at the air horn.
    8.  
    9. Disconnect the fuel line at the fuel filter.
    10.  
    11. Unfasten the electrically assisted choke wire at its connector.
    12.  
    13. Unfasten the electrical connections for the throttle control, idle tracking switch and Wide Open Throttle (WOT) air conditioning cut-off switch, if so equipped.
    14.  
    15. On feedback model carburetors, disconnect the feedback solenoid, idle speed control motor and throttle position sensor wires.
    16.  
    17. Remove the carburetor retaining nuts. Lift off the carburetor carefully, taking care not to spill any fuel. Remove the carburetor mounting gasket and discard it. Remove the carburetor mounting spacer, if so equipped, from the intake manifold. To install:
    18.  
    19. Prior to installation, clean the gasket mounting surfaces of the intake manifold, spacer (if so equipped), and carburetor. When using a spacer, use two new gaskets, sandwiching the spacer between the gaskets. If a spacer is not used, only one new carburetor mounting gasket is required.
    20.  
    21. Place the new gasket(s) and spacer (if so equipped) on the carburetor mounting studs. Position the carburetor on top of the gasket and hand-tighten the retaining nuts. Then tighten the nuts in a crisscross pattern to 12-15 ft. lbs. (16-19 Nm).
    22.  
    23. Connect the fuel line, throttle cable or rod, and the appropriate vacuum lines.
    24.  
    25. Connect the fuel bowl vent hose to the air horn.
    26.  
    27. Fasten the electrical connections for the throttle control, idle tracking switch and WOT air conditioning cut-off switch, if so equipped.
    28.  
    29. Connect the electrically assisted choke wire. On feedback model carburetors, connect the feedback solenoid, idle speed control motor and throttle position sensor wires.
    30.  
    31. Install the air cleaner assembly.
    32.  
    33. Check and adjust the engine idle speed settings, as outlined in Engine Performance and Tune-Up .
    34.  

    Holley 5200 or 6500

    1. Remove the air cleaner assembly.
    2.  
    3. Disconnect the throttle cable from the throttle lever.
    4.  
    5. Disconnect the canister bowl vent tube, bowl vent tube, vacuum throttle kicker tube (if so equipped), and feedback tube (model 6500 only).
    6.  
    7. Disconnect the distributor vacuum tube, Thermactor® dump valve vacuum tube, EGR vacuum tube and external choke pulldown vacuum tube (if so equipped).
    8.  
    9. Disconnect the fuel inlet line.
    10.  
    11. Unfasten the electric choke cap, bowl vent switch connector, throttle solenoid connector (if so equipped) and idle tracking switch connector.
    12.  
    13. Remove the carburetor retaining nuts. Lift off the carburetor carefully, taking care not to spill any fuel. Remove the carburetor mounting gasket and discard it. Remove the carburetor mounting spacer, if so equipped, from the intake manifold. To install:
    14.  
    15. Prior to installation, clean the gasket mounting surfaces of the intake manifold, spacer (if so equipped), and carburetor. When using a spacer, use two new gaskets, sandwiching the spacer between the gaskets. If a spacer is not used, only one new carburetor mounting gasket is required.
    16.  
    17. Place the new gasket(s) and spacer (if so equipped) on the carburetor mounting studs. Position the carburetor on top of the gasket and hand-tighten the retaining nuts. Then tighten the nuts in a crisscross pattern to 10-14 ft. lbs. (13-18 Nm).
    18.  
    19. Connect the electric choke, bowl vent switch, throttle solenoid (if so equipped) and idle tracking switch.
    20.  
    21. Connect the canister bowl vent tube, bowl vent tube, vacuum throttle kicker tube (if so equipped), and feedback tube (model 6500 only).
    22.  
    23. Connect the distributor vacuum tube, Thermactor® dump valve vacuum tube, EGR vacuum tube and external choke pulldown vacuum tube (if so equipped).
    24.  
    25. Connect the fuel inlet line.
    26.  
    27. Connect the throttle cable at the throttle lever.
    28.  
    29. Install the air cleaner assembly.
    30.  
    31. Adjust the curb idle and fast idle speed settings, if necessary, as outlined in Engine Performance and Tune-Up .
    32.  

    Holley 1946
    1. Remove the air cleaner assembly.
    2.  
    3. Disconnect the throttle cable from the throttle lever.
    4.  
    5. Disconnect the distributor vacuum line, EGR vacuum line, venturi vacuum line and fuel line.
    6.  
    7. Disconnect the choke heat tube, if so equipped.
    8.  
    9. Unfasten the throttle solenoid positioner and choke cap at their electrical connections.
    10.  
    11. Remove the canister bowl vent electrical connector and the canister vent hose.
    12.  
    13. Remove the carburetor retaining nuts. Lift off the carburetor carefully, taking care not to spill any fuel. Remove the carburetor mounting gasket and discard it. Remove the carburetor mounting spacer, if so equipped, from the intake manifold. To install:
    14.  
    15. Prior to installation, clean the gasket mounting surfaces of the intake manifold, spacer (if so equipped), and carburetor. When using a spacer, use two new gaskets, sandwiching the spacer between the gaskets. If a spacer is not used, only one new carburetor mounting gasket is required.
    16.  
    17. Place the new gasket(s) and spacer (if so equipped) on the carburetor mounting studs. Position the carburetor on top of the gasket and hand-tighten the retaining nuts. Then tighten the nuts in a crisscross pattern to 12-15 ft. lbs. (16-19 Nm).
    18.  
    19. Connect the fuel line, throttle cable, distributor vacuum line, EGR vacuum line, and venturi vacuum line.
    20.  
    21. Connect the canister vent hose and the canister bowl vent electrical connector.
    22.  
    23. Connect the choke heat tube, if so equipped.
    24.  
    25. Fasten the throttle solenoid positioner and choke cap at their electrical connections.
    26.  
    27. Install the air cleaner assembly.
    28.  
    29. Adjust the curb idle and fast idle speed settings, if necessary. (On 1979 models, also adjust the slow idle speed with the throttle solenoid positioner OFF.)
    30.  

    Holley 4180

    1. Remove the air cleaner assembly.
    2.  
    3. Disconnect the throttle rod from the throttle lever.
    4.  
    5. Unfasten the distributor vacuum lines, PCV hose, fuel line and any electrical connections.
    6.  
    7. Disconnect the choke heat tube, if so equipped.
    8.  
    9. Remove the carburetor retaining nuts. Lift off the carburetor carefully, taking care not to spill any fuel. Remove the carburetor mounting gasket and discard it. Remove the carburetor mounting spacer from the intake manifold. To install:
    10.  
    11. Prior to installation, clean the gasket mounting surfaces of the intake manifold, spacer and carburetor. When using a spacer, use two new gaskets, sandwiching the spacer between the gaskets.
    12.  
    13. Place the new gaskets and spacer on the carburetor mounting studs. Position the carburetor on top of the gasket and hand-tighten the retaining nuts. Then tighten the nuts in a crisscross pattern to 14-1 ft. lbs. (18-11 Nm).
    14.  
    15. Fasten the throttle rod, vacuum lines, PCV hose, fuel line and electrical connections.
    16.  
    17. Connect the choke heat tube, if so equipped.
    18.  
    19. Install the air cleaner assembly.
    20.  
    21. Check and adjust the idle speed settings, if necessary, as outlined in Engine Performance and Tune-Up .
    22.  

    All Other Carburetors

    Prior to removing any wire harness, vacuum line or cable, properly mark or tag the item.

    1. Remove the air cleaner.
    2.  
    3. Disconnect the throttle cable or rod at the throttle lever. Unfasten the distributor vacuum line, exhaust gas recirculation line (1973 and later models), inline fuel filter, choke heat tube and the positive crankcase ventilation hose at the carburetor.
    4.  
    5. Unfasten the throttle solenoid (if so equipped) and electric choke assist (1973 and later models) at their connectors. Remove the wires to the carburetor on the 710 VV.
    6.  
    7. Remove the carburetor retaining nuts. Lift off the carburetor carefully, taking care not to spill any fuel. Remove the carburetor mounting gasket and discard it. Remove the carburetor mounting spacer, if so equipped, from the intake manifold. To install:
    8.  
    9. Prior to installation, clean the gasket mounting surfaces of the intake manifold, spacer, (if so equipped), and carburetor. When using a spacer, use two new gaskets, sandwiching the spacer between the gaskets. If a spacer is not used, only one new carburetor mounting gasket is required.
    10.  
    11. Place the new gasket(s) and spacer (if so equipped) on the carburetor mounting studs. Position the carburetor on top of the gasket and hand-tighten the retaining nuts. Then tighten the nuts in a crisscross pattern to 10-15 ft. lbs. (13-19 Nm).
    12.  
    13. Connect the throttle linkage, the distributor vacuum line, exhaust gas recirculation line (1973 and later models), inline fuel filter, choke heat tube, positive crankcase ventilation hose, throttle solenoid (if so equipped) and electric-choke assist (1973 and later models).
    14.  
    15. Adjust the curb idle speed, the idle fuel mixture and the accelerator pump stroke (Autolite/Motorcraft 2 and 4-barrel carburetors only).
    16.  

    OVERHAUL



    Efficient carburetion depends on careful cleaning and inspection during overhaul, since dirt, gum, water, or varnish in or on the carburetor parts can be responsible for poor performance.

    Overhaul your carburetor in a clean, dust free area. Carefully disassemble the carburetor, referring often to the exploded views. Keep all similar and look-alike parts segregated during the disassembly and cleaning to avoid accidental interchange during assembly. Make a note of all jet sizes.

    When the carburetor is disassembled, wash all parts (except diaphragms, electric choke units, pump plunger, and any other plastic, leather, fiber, or rubber parts) in clean carburetor solvent. Do not leave parts in the solvent any longer than is necessary to sufficiently loosen the deposits. Excessive cleaning may remove the special finish from the float bowl and choke valve bodies, leaving these parts unfit for service. Rinse all parts in clean solvent and blow them dry with compressed air or allow them to air dry. Wipe clean all cork, plastic, leather, and fiber parts with a clean, lint-free cloth.

    Blow out all passages and jets with compressed air and be sure that there are no restrictions or blockages. Never use wire of similar tools to clean jets, fuel passages, or air bleeds. Clean all jets and valves separately to avoid accidental interchange.

    Check all parts for wear or damage. If wear or damage is found, replace the defective parts. Especially check the following:

    1. Check the float needle and seat for wear. If wear is found, replace the complete assembly.
    2.  
    3. Check the float hinge pin for wear and the float(s) for dents or distortion. Replace the float if fuel has leaked into it.
    4.  
    5. Check the throttle and choke shaft bores for wear or an out-of-round condition. Damage or wear to the throttle arm, shaft, or shaft bore will often require replacement of the throttle body. These parts require a close tolerance of fit. Slight wear may allow air linkage, which could affect starting and idling.
    6.  

    Throttle shafts and bushings are not included in overhaul kits. They usually can be purchased separately.

    1. Inspect the idle mixture adjusting needles for burrs or grooves. Any such condition requires replacement of the needle, since you will not be able to obtain a satisfactory idle.
    2.  
    3. Check the bowl cover for warped surfaces with a straightedge.
    4.  
    5. Closely inspect the valves and seats for wear and damage, replacing as necessary.
    6.  
    7. After the carburetor is assembled, check the choke valve for freedom of operation.
    8.  

    Carburetor overhaul kits are recommended for each overhaul. These kits contain all gaskets and new parts to replace those which deteriorate most rapidly. Failure to replace all parts supplied with the kit (especially gaskets) can result in poor performance later.

    Some carburetor manufacturers supply overhaul kits of three basic types: minor repair; major repair; and gasket kits. Basically, they contain the following:

    Minor Repair Kits:


    All gaskets
     
    Float needle valve
     
    Volume control screw
     
    All diaphragms
     
    Spring for the pump diaphragm
     

    Major Repair Kits:


    All jets and gaskets
     
    All diaphragms
     
    Float needle valve
     
    Volume control screw
     
    Pump ball valve
     
    Float
     
    Complete intermediate rod
     
    Intermediate pump lever
     
    Some cover hold-down screws and washers
     

    Gasket Kits:


    All gaskets
     

    After cleaning and checking all components, reassemble the carburetor, using new parts referring to the exploded view as needed. When reassembling, make sure that all screws and jets are tight in their seats, but do not overtighten as the tops will be distorted. Tighten all screws gradually, in rotation. Do not tighten needle valves into their seats; uneven jetting will result. Always use new gaskets. Be sure to adjust the float level when reassembling.

    ADJUSTMENTS



    Automatic Choke
    1971-78 MODELS

    Original equipment carburetors have adjustable choke caps. On a vehicle of this type, the reaction of the choke to engine temperature can be controlled by positioning and rotating the cap in relation to an index mark or reference point. In spite of their adjustability, these carburetors each have a preferred setting, as determined by the manufacturer. Most original equipment carburetors on 1980 and later vehicles utilize adjustment-limiting or non-adjustable choke caps. The inclusion of a locking/indexing plate or spacer with locating tabs eliminates the need for choke cap adjustment. Nevertheless, the removal and installation procedures for these non-adjustable choke caps are essentially the same as those for their adjustable counterparts. One significant difference is in the type of fastener used to retain the caps. Generally, regular slotted screws are used to retain adjustable choke caps, thereby permitting easy removal. Non-adjustable choke caps, on the other hand, are retained by a combination of screws and either rivets or break-away screws. Such unslotted-head fasteners require different removal tools and techniques, as described below.

    1979 CARBURETORS

    See Figure 12

    1. Remove the air cleaner assembly.
    2.  
    3. Loosen the thermostatic spring housing retaining screws.
    4.  
    5. Set the spring housing to the specified index mark, by rotating the housing. (Refer to the appropriate Carburetor Specifications chart, later in this section.)
    6.  

    If the choke cap was removed, be sure that the choke cap gasket or spacer is in place and that the choke cap engages the bimetal loop on the choke thermostatic lever.

    1. Line up the holes in the choke cap retainer, if removed, and fasten the retaining screws.
    2.  
    3. Install the air cleaner assembly, if no further adjustments are required at this time.
    4.  



    Click image to see an enlarged view

    Fig. Fig. 12: Disassembled automatic choke

    1980-86 CARBURETORS

    The carburetors used on most 1980 and later vehicles have adjustment-limiting or non-adjustable choke caps which must line up with a locking/indexing plate or spacer. Although non-adjustable, these choke caps may have to be removed if defective, or when performing other carburetor procedures.

    1. Remove the air cleaner assembly from the carburetor.
    2.  
    3. If the choke cap retainer is fastened with unslotted-head fasteners, determine whether those fasteners are rivets or break-away screws.
    4.  

    Break-away screws are threaded like regular screws, but once they are sufficiently tightened, the slotted upper portion breaks off. Unlike rivets, they can be unscrewed if a new slot is created.

    1. To remove break-away screws, use a hacksaw to carefully cut a slot in the head of each break-away screw, so that they can be removed with a straight-blade screwdriver. Proceed to Step 5.
    2.  
    3. To remove rivets, proceed as follows: This procedure must be followed to retain the hole size.
      1. Check the choke cap retainer rivets to determine if the mandrel is well below the rivet head. If the mandrel appears to be at or within the rivet head thickness, drive it down or out with a 1 / 16 in. diameter punch.
      2.  
      3. Use a 1 / 8 in. diameter or No. 30 (.1285 in. diameter) drill bit for drilling the rivet heads. Drill into the rivet head until the rivet head comes loose from the rivet body.
      4.  
      5. After the rivet head is removed, drive the remaining portion of the rivet out of the hole with an 1 / 8 in. diameter punch.
      6.  
      7. Repeat Step 4 for the remaining rivet.
      8.  

    4.  
    5. Remove the screw(s) with a proper size screwdriver.
    6.  
    7. Remove the retainer, choke cap, locking/indexing plate and/or gasket(s), as equipped.
    8.  

    On some carburetors, epoxy cement was applied during production to both sides of the gasket. In this case, remove the gasket by inserting a sharp, flat chisel or knife between the gasket layers. Be sure to clean any remaining epoxy and gasket from the mating surfaces with a gasket scraper.

    To install:
    1. Install the choke cap gasket(s) and locking/indexing plate or spacer, as equipped. (Replace any damaged gasket(s) and be sure to apply epoxy cement or equivalent to any gasket which was originally cemented.)
    2.  
    3. Install the choke cap, making certain that the bimetal loop is positioned around the choke lever tang.
    4.  
    5. While holding the cap in place, actuate the choke plate to make certain the bimetal loop is properly engaged with the lever tang. Set the retainer over the choke cap and orient the retainer to match the holes in the casting. (The holes are not equally spaced on some models.) Make sure the retainer is not upside down.
    6.  

    1983-84 Holley 4180 carburetors have an adjustable choke cap, which must be aligned with the proper index mark. (Refer to the Carburetor Specifications Chart, found later in this section.) To properly position the cap, loosely install the choke cap retainer screws before aligning the cap. Once the cap is properly positioned, tighten the retainer screws.

    1. To replace break-away screws, install new break-away screws and tighten until their heads break off. (If you prefer, these fasteners may be replaced by conventional screws of the same installed size.)
    2.  
    3. To replace rivets, proceed as follows:
      1. Place a rivet in the rivet gun and trigger it lightly to retain the rivet ( 1 / 8 in. diameter x 1 / 2 in. long x 1 / 4 in. diameter head).
      2.  
      3. Press the rivet fully into the casting after passing through the retainer and "pop'' the rivet, so that the mandrel breaks off. Be careful that the rivet mandrel does not lodge in the carburetor mechanism when it separates from the rivet.
      4.  
      5. Repeat this step for the remaining rivet.
      6.  

    4.  
    5. Install and tighten the remaining conventional screw(s).
    6.  
    7. Install the air cleaner assembly, if no further adjustments are required at this time.
    8.  

    Choke Plate Pulldown Clearance

    AUTOLITE 1101
    1. Remove the air cleaner assembly.
    2.  
    3. Remove the choke cover and thermostatic coil assembly. Block the throttle valve half open so that the fast idle screw does not contact the fast idle cam.
    4.  
    5. Bend a 0.025 in. (0.9mm) wire gauge at a 90º angle about 1 / 8 in. (3mm) from the end. Insert the bent end between the lower edge of the choke piston slot and the upper edge of the right hand slot in the choke housing.
    6.  
    7. Move the piston lever counterclockwise until the gauge fits snugly in the slot. Hold the gauge in place by exerting light pressure on the lever.
    8.  
    9. Insert a drill or gauge of the specified thickness (see Carburetor Specifications chart) between the lower edge of the choke plate and the air horn wall.
    10.  
    11. To adjust, carefully bend the choke piston link (in an S or Z-shaped bend) until the choke plate clearance is that of the drill gauge.
    12.  
    13. After adjustment, install the choke cover and adjust it.
    14.  
    15. Install the air cleaner.
    16.  

    CARTER YFA-PISTON TYPE

    See Figure 13

    1. Remove the air cleaner assembly.
    2.  
    3. Remove the retainer, choke cap and gasket, as described previously in this section.
    4.  
    5. Bend a 0.011 in. diameter wire gauge at a 90º angle, approximately 1 / 8 in. (3mm) from one end. Insert the bent end of the gauge between the choke piston slot and the right hand slot in the choke housing. Rotate the choke piston lever counterclockwise until the gauge is shut in the piston slot.
    6.  
    7. Apply light pressure on the choke piston lever to hold the gauge in place. Then, measure the clearance between the lower edge of the choke plate and the carburetor bore using a drill bit with a diameter equal to the specified pulldown clearance. (Refer to the Carburetor Specifications chart, later in this section.)
    8.  
    9. Bend the choke piston lever to obtain the proper clearance. Be careful not to distort the piston link.
    10.  
    11. Install the gasket, choke cap and retainer.
    12.  
    13. Fasten the retainer screw(s) and apply new rivets, where necessary.
    14.  
    15. Install the air cleaner assembly, if no further adjustments are required at this time.
    16.  



    Click image to see an enlarged view

    Fig. Fig. 13: Choke plate pulldown adjustment-Carter YFA carburetor with piston-type choke

    CARTER YFA-DIAPHRAGM-TYPE

    See Figure 14

    1. Activate the pulldown motor by applying an external vacuum source.
    2.  
    3. Close the choke plate as far as possible without forcing it.
    4.  
    5. Using a drill bit of the specified size (as indicated in the Carburetor Specifications chart, later in this section), measure the clearance between the lower edge of the choke plate and the air horn wall.
    6.  
    7. If adjustment is necessary, bend the choke diaphragm link as required.
    8.  
    9. Reconnect the pulldown motor vacuum line.
    10.  



    Click image to see an enlarged view

    Fig. Fig. 14: Choke plate pulldown adjustment-Carter YFA carburetor with diaphragm-type choke

    MOTORCRAFT 200
    1. Remove the air cleaner.
    2.  
    3. With the engine at normal operating temperature, loosen the choke thermostatic spring housing retaining screws. Set the housing 90ºs in the right direction.
    4.  
    5. Disconnect and remove the choke heat tube from the choke housing.
    6.  
    7. Turn the fast idle adjusting screw outward one full turn.
    8.  
    9. Start the engine. Use a drill of a diameter specified in the chart at the end of this section to check the clearance between the lower edge of the choke plate and the air horn wall.
    10.  
    11. To adjust the clearance, turn the diaphragm stop screw (located on the underside of the choke diaphragm housing). Turning clockwise will decrease the clearance; counterclockwise will increase it.
    12.  
    13. Connect the choke heat tube, and set the choke thermostatic spring housing to the proper specification. Adjust the fast idle speed to specification.
    14.  

    MOTORCRAFT 42

    See Figures 15 and 16

    1. Remove the air cleaner assembly.
    2.  
    3. Loosen the choke cap. (If the cap has an adjustment-limiting design, remove the fasteners as described above. Temporarily remove the locking/indexing plate and install the cap with conventional screws.) Do not tighten the screws.
    4.  
    5. Rotate the choke thermostatic housing counterclockwise to lightly close the choke plate, and then an additional 90º in the same direction. Tighten the screws to hold this setting.
    6.  
    7. Activate the pulldown motor by applying an external vacuum source to it, or by pushing the choke pulldown diaphragm's connecting link into the retracted position.
    8.  
    9. Using a drill bit of the specified diameter (as indicated in the Carburetor Specifications chart, later in this section), measure the clearance between the lower edge of the choke plate and the air horn wall.
    10.  
    11. Turn the adjusting screw on the pulldown motor clockwise to decrease the pulldown, or counterclockwise to increase it.
    12.  

    After each pulldown adjustment, it is necessary to check the fast idle cam setting. This procedure is covered later in this section.

    1. After the final adjustment, reset the choke housing cap to its proper position. (Be sure to replace the locking/indexing plate, if so equipped, and install new fasteners where necessary.)
    2.  
    3. If disconnected, reconnect the vacuum hose to the pulldown motor.
    4.  
    5. Install the air cleaner assembly, if no further adjustments are required at this time.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 15: Pulldown motor adjustment screw-Motorcraft 42 carburetor



    Click image to see an enlarged view

    Fig. Fig. 16: Choke plate pulldown adjustment-Motorcraft 42 carburetor

    AUTOLITE/MOTORCRAFT 4300, 4350
    1. Follow Steps 1-5 of the Autolite 1101 carburetor adjustment procedure.
    2.  
    3. To adjust, loosen the hex head screw (left hand thread) on the choke plate shaft and pry the link away from the tapered shaft. Using a drill gauge 0.010 in. thinner than the specified clearance (to allow for tolerances in the linkage), insert the gauge between the lower edge of the choke plate and the air horn wall. Hold the choke plate against the gauge and maintain a light pressure in a counterclockwise direction on the choke lever. With the choke piston snug against the 0.025 in. wire gauge and the choke plate against the 0.010 in. smaller drill gauge, tighten the hex head screw (left hand thread) on the choke plate shaft. After tightening the hex head screw, make a final check using a drill gauge of the specified clearance between the choke plate and air horn.
    4.  
    5. After adjustment, install the choke cover and adjust.
    6.  
    7. Install the air cleaner.
    8.  

    1979 MOTORCRAFT 510 OR 6500
    1. Remove the retaining screws and ring retaining the choke thermostatic spring housing.
    2.  
    3. Remove the thermostatic spring housing and the electric choke heater.
    4.  
    5. Set the fast idle cam on the second step.
    6.  
    7. Attach a rubber band to the choke operating lever to take up any slack in the linkage.
    8.  
    9. Push the diaphragm stem against its stop with a screwdriver, and insert a drill bit of the specified diameter (as indicated in the Carburetor Specifications chart, later in this section), between the lower edge of the choke plate and the air horn wall.
    10.  
    11. Turn the diaphragm adjusting screw in or out to get the proper clearance.
    12.  
    13. Install the electric choke heater, thermostatic spring housing, retaining ring and attaching screws. (Be sure that the choke plate is in the fully closed position before installing the electric choke heater.)
    14.  
    15. Rotate the housing to the specified index mark and tighten the screws.
    16.  

    1980-81 MOTORCRAFT 510 OR 6500

    See Figures 17 and 18

    1. Remove the retainer, choke cap and locking/indexing plate as described earlier in this section.
    2.  
    3. Remove the plastic dust cover, if so equipped.
    4.  
    5. Set the fast idle adjusting screw on the high step of the fast idle cam.
    6.  
    7. Attach a rubber band, as illustrated, to remove slack from the choke linkage. Push the diaphragm stem against its stop with a screwdriver, and insert a drill bit of the specified diameter (as indicated in the Carburetor Specifications chart, later in this section,) between the lower edge of the choke plate and the air horn wall.
    8.  
    9. If the original choke pulldown diaphragm cover is still in place, and an adjustment is necessary, a service replacement kit will be required. This kit contains a new choke pulldown diaphragm cover, adjusting screw and a cup plug. Proceed as follows:
      1. Remove the three choke pulldown diaphragm cover retaining screws and the cover.
      2.  
      3. Install a new cover and adjusting screw.
      4.  

    10.  
    11. Turn the diaphragm adjusting screw clockwise to decrease, or counterclockwise to increase the clearance.
    12.  
    13. When the adjustment is complete, install a new cup plug in the choke pulldown adjustment access opening.
    14.  
    15. Remove the rubber band and install the plastic dust cover, if so equipped.
    16.  
    17. Install the locking and indexing plate, the choke cap and retainer. Be sure that the bimetal loop is properly engaged.
    18.  
    19. Fasten the retainer screw(s) and apply new rivets, where necessary.
    20.  



    Click image to see an enlarged view

    Fig. Fig. 17: Choke plate pulldown adjustment-Motorcraft 5200 or 6500 carburetor



    Click image to see an enlarged view

    Fig. Fig. 18: Fast idle cam setting-1980-82 Motorcraft 510 or 6500 carburetor

    HOLLEY 1946

    Early models of this carburetor can be adjusted, if necessary, without drilling or removing the carburetor. If the choke pulldown diaphragm's connecting link has a U-shaped bend, adjustments are simply made by bending the link.

    See Figures 19 and 20

    1. Remove the retainer and choke cap, as described above. (If the pulldown diaphragm's connecting link has a U-shaped bend, simply loosen the choke cap's retainer screws, and proceed to Step 4.)
    2.  
    3. Temporarily remove the choke locking and indexing plate.
    4.  
    5. Loosely reassemble the choke cap and retainer with the two screws.
    6.  
    7. Rotate the cap counterclockwise to lightly close the choke plate, and then an additional 90º in the same direction. Tighten the screws to hold this setting.
    8.  
    9. Activate the pulldown motor by applying an external vacuum source.
    10.  
    11. Using a drill bit of the specified diameter (as indicated in the Carburetor Specifications chart, later in this section), measure the clearance between the upper edge of the choke plate and the air horn wall.
    12.  

    The remaining steps only apply to those carburetors in which the pulldown diaphragm has a straight connecting link. For early models with a U-shaped link, bend the link until the specified clearance is achieved, then set the choke cap to the original setting and tighten the screws.

    1. If an adjustment is necessary, drill a 3 / 32 in. diameter hole through the hardened steel plug at the base of the pulldown motor, and remove the plug with a tap. (It may be necessary to first remove the carburetor, in order to allow sufficient access. If so, follow the instructions later in this section.)
    2.  
    3. Repeat Steps 6 and 7, and turn the adjusting screw in or out as required until the adjustment is within specifications.
    4.  
    5. Install a new steel plug in the adjusting screw access hole.
    6.  
    7. Remove the screws, retainer and choke cap.
    8.  
    9. Install the choke locking and indexing plate, along with the choke cap, retainer and screws. Install new rivets, as described above.
    10.  
    11. Install the carburetor and related parts, if removed.
    12.  



    Click image to see an enlarged view

    Fig. Fig. 19: Choke plate pulldown adjustment-Holley 1946 early-model carburetor



    Click image to see an enlarged view

    Fig. Fig. 20: Choke plate pulldown adjustment-Holley 1946 carburetor

    HOLLEY 4180

    See Figure 21

    1. Remove the choke thermostat housing, gasket and retainer, as described above.
    2.  
    3. Insert a thin piece of wire into the choke piston bore to move the piston down against the stop screw.
    4.  
    5. Maintain light closing pressure on the choke plate, and measure the gap between the lower edge of the choke plate and the air horn wall.
    6.  
    7. Turn the adjustment screw clockwise to decrease or counterclockwise to increase the gap setting. Be sure to close the choke plate during adjustment, to avoid turning the screw into the side of the piston.
    8.  
    9. Remove the wire and install the choke thermostat housing, gasket and retainer. Use new fasteners when replacing rivets or break-away screws.
    10.  



    Click image to see an enlarged view

    Fig. Fig. 21: Choke plate pulldown adjustment-Holley 4180 carburetor

    Float Level
    AUTOLITE 1101

    See Figure 22

    1. Remove the carburetor air horn and gasket from the carburetor.
    2.  
    3. Measure the distance from the gasket surface of the air horn to the top of the float. If the measurement is not within the specified tolerance, bend the float arm tab as necessary to obtain the specified dimension. Be careful not to exert any pressure on the fuel inlet needle, as this will damage it and result in an improper fuel level within the float bowl.
    4.  
    5. Install the carburetor air horn to the main body of the carburetor, using a new gasket.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 22: Float level adjustment-Autolite 1101

    CARTER YFA

    See Figure 23

    The dry float fuel level adjustment is a final float or fuel level adjustment.

    1. Remove the air cleaner assembly.
    2.  
    3. Disconnect the fuel inlet line at the filter, and the vacuum pulldown hose at the pulldown motor.
    4.  
    5. Unfasten the electric choke wire at the connector and at the clip on the throttle control bracket. Remove the throttle control bracket assembly from the main body. Remove the external bowl vent line.
    6.  
    7. Remove the wire clip retaining the link which joins the fast idle choke lever to the fast idle cam, and remove the link.
    8.  
    9. Remove the air horn attaching screws and carburetor identification tag. Remove the air horn and gasket.
    10.  
    11. Invert the air horn assembly and check the clearance from the top of the float to the surface of the air horn with a T-scale or float level gauge. The air horn should be held at eye level when gauging, and the float arm should be resting on the needle pin.
    12.  
    13. Do not exert pressure on the needle valve when measuring or adjusting the float. Bend the float arm as necessary to adjust the float level to specifications.
    14.  


    CAUTION
    Do not bend the tab at the end of the float arm, as it prevents the float from striking the bottom of the fuel bowl when empty and keeps the needle in place.

    1. Install the air horn with a new gasket. Be sure to install the identification tag in its proper location and tighten the attaching screws to 27-37 inch lbs. (3-4 Nm).
    2.  
    3. Connect the external bowl vent line.
    4.  
    5. Install the throttle control bracket assembly on the main body.
    6.  
    7. Position the link and plastic bushing which join the fast idle cam to the fast idle choke lever, and retain them in place on the fast idle cam with the plastic bushing and wire clip. Make sure that the mechanical fuel bowl vent rod is engaged with the forked actuating lever, if so equipped.
    8.  
    9. Connect the fuel inlet line to the fuel filter, and the vacuum line to the pulldown motor.
    10.  
    11. Connect the electric choke wire, and clip the wire to the throttle control bracket.
    12.  
    13. Install the air cleaner assembly.
    14.  



    Click image to see an enlarged view

    Fig. Fig. 23: Fuel level float adjustment-Carter YFA carburetor

    MOTORCRAFT 5200 OR 6500
    1. Remove the bowl cover (air horn) attaching screws and lockwashers.
    2.  
    3. Remove the plastic retainer bushings from the choke rod and remove the air horn. Be sure that the gasket is not attached.
    4.  
    5. Turn the air horn upside down. With the float tang resting lightly on the spring loaded fuel inlet needle, measure the clearance between the edge of the float and the air horn.
    6.  
    7. To adjust the float level, bend the float tang. Make sure that both floats are adjusted equally.
    8.  
    9. Hold the air horn in its normal position to check and adjust the float drop, if necessary.
    10.  
    11. Position the air horn and gasket on the main body, and install the attaching screws and lockwashers. Tighten the attaching screws to 1 inch lbs. (2 Nm).
    12.  
    13. Install the plastic retainer bushings on the choke rod.
    14.  

    HOLLEY 1946

    See Figure 24

    This setting of the float level adjustment must be done with the carburetor removed from the engine.

    1. Remove the air horn attaching screws and carburetor identification tag. Remove the air horn and gasket.
    2.  
    3. Place a finger over the hinge pin retainer and invert the main body. Catch the accelerator pump check ball and weight when they fall out.
    4.  
    5. Lay a ruler across the housing under the floats. The lowest point of the floats should be just touching the ruler for all except California models. For California models, the ruler should just contact the heel (raised step) of the floats.
    6.  
    7. Bend the float tangs to adjust. Once this adjustment is correct, turn the main body right side up and check the float alignment. The floats should move freely without touching the fuel bowl walls. If the floats are misaligned, straighten them by bending the float arms. Recheck the float level adjustment, and adjust if necessary.
    8.  
    9. Insert the accelerator pump check ball and weight.
    10.  
    11. Install the air horn with a new gasket, and fasten with the screws. Be sure to install the identification tag in its proper location.
    12.  



    Click image to see an enlarged view

    Fig. Fig. 24: Float level adjustment-Holley 1933 carburetor

    HOLLEY 4180

    To perform a preliminary dry float adjustment on both the primary and secondary fuel bowl assemblies, remove each fuel bowl and invert it, allowing the float to rest on the fuel inlet valve and seat assembly. The fuel inlet valve and seat can be rotated until the float is parallel with the fuel bowl floor (actually, the top of the fuel bowl chamber when inverted). Note that this is an initial dry float setting which must be rechecked with the carburetor assembled and on the engine to obtain the proper wet fuel level.

    This carburetor has an externally adjustable needle and seat assembly which allows the fuel level to be checked and adjusted without removing the carburetor from the engine.

    1. Run the engine with the vehicle resting on a level surface until the engine reaches normal operating temperature.
    2.  
    3. Remove the air cleaner assembly.
    4.  
    5. Place a suitable container or an absorbent cloth below the fuel level sight plug in the fuel bowl.
    6.  
    7. Run the engine at 1000 rpm for about 30 seconds to stabilize the fuel level.
    8.  
    9. Stop the engine and remove the sight plug and gasket on the primary float bowl. The fuel level in the bowl should be at the lower edge of the sight plug hole, plus or minus 1 / 16 in. (1.5mm). If the level is too high, loosen one of the lower fuel bowl retaining screws and drain the fuel from the bowl.
    10.  


    CAUTION
    Never loosen the lockscrew or nut, or attempt to adjust the fuel level with the sight plug removed or the engine running, since fuel will spray out, creating a fire hazard!

    1. To adjust the fuel level, loosen the lockscrew on top of the fuel bowl just enough to allow the adjusting nut to be turned. Turn the adjusting nut about 1 / 2 turn clockwise to lower the fuel level, or about 1 / 2 turn counterclockwise to raise the fuel level. (By turning the adjusting nut 5 / 16 of a turn, the fuel level will change 1 / 16 in. (1.5mm) at the sight plug.) Tighten the lock screw and install the sight plug, using the old gasket.
    2.  
    3. Start the engine and allow the fuel level to stabilize again, by running the engine at 1000 rpm for about 30 seconds. Stop the engine and re-check the fuel level as outlined in Step 5.
    4.  
    5. Repeat the procedure in Step 6 until the fuel level is at the bottom of the sight plug hole. Install the sight plug using a new gasket.
    6.  
    7. Repeat Steps 5-8 for the secondary fuel bowl adjustment.
    8.  

    The secondary throttle is used to stabilize the fuel level in the secondary fuel bowl.

    1. Install the air cleaner assembly if no further adjustments are necessary.
    2.  

    AUTOLITE/MOTORCRAFT 200, 42, 4100 (DRY ADJUSTMENT)

    This preliminary setting of the float level adjustment must be performed with the carburetor removed from the engine.

    1. Remove the air horn and see that the float is raised and the fuel inlet needle is seated. Check the distance between the top surface of the main body (with the gasket removed) and the top surface of the float. Depress the float tab to seat the fuel inlet needle. Take a measurement near the center of the float, at a point 1 / 8 in. (3mm) from the free end. If you are using a prefabricated float gauge, place the gauge in the corner of the enlarged end section of the fuel bowl. The gauge should touch the float near the end, but not on the end radius.
    2.  
    3. If necessary, bend the tab on the end of the float to bring the setting within the specified limits.
    4.  

    AUTOLITE/MOTORCRAFT 200, 42, 4100 (WET ADJUSTMENT)

    See Figure 25

    1. Bring the engine to its normal operating temperature. Park the car on as nearly level a surface as possible, and stop the engine.
    2.  
    3. Remove the air cleaner assembly from the carburetor.
    4.  
    5. Remove the air horn retaining screws and the carburetor identification tag. Leave the air horn and gasket in position on the carburetor main body. Start the engine, let it idle for several minutes. Rotate the air horn out of the way, and remove the gasket to provide access to the float assembly.
    6.  
    7. With the engine idling, use a standard depth scale to measure the vertical distance from the top machined surface of the carburetor main body to the level of the fuel in the fuel bowl. This measurement must be made at least 1 / 4 in. (6mm) away from any vertical surface in order to assure an accurate reading.
    8.  
    9. Stop the engine before making any adjustment to the float level. Adjustment is accomplished by bending the float tab (which contacts the fuel inlet valve) up or down as required to raise or lower the fuel level. After making an adjustment, start the engine, and allow it to idle for several minutes before repeating the fuel level check. Repeat as necessary until the proper fuel level is attained.
    10.  
    11. Reinstall the air horn with a new gasket and secure it with the screws. Install the identification tag in its proper location.
    12.  
    13. Check the idle speed, mixture, and dashpot adjustments. Install the air cleaner assembly.
    14.  



    Click image to see an enlarged view

    Fig. Fig. 25: Wet float level adjustment-Autolite/Motorcraft 200, 42, 4100

    MOTORCRAFT 4300, 4350

    See Figures 26 and 27

    1. Refer to the illustration for construction of a tool used in checking the parallel setting of the dual pontoons.
    2.  
    3. Install the gauge on the carburetor and set it to the specified height.
    4.  
    5. Check the clearance and alignment of the pontoons to the gauge. Both pontoons should just barely touch the gauge for the proper setting. Pontoons may be aligned if necessary by slightly twisting them.
    6.  
    7. To adjust the float level, bend the primary needle tab down to raise the float and up to lower it.
    8.  



    Click image to see an enlarged view

    Fig. Fig. 26: Float level adjustment with rebuild kit gauge-Motorcraft 4300, 4350



    Click image to see an enlarged view

    Fig. Fig. 27: Float gauge and tool-Motorcraft 4300, 4350

    CARTER THERMO-QUAD
    1. Taking note of their placement, disconnect all linkages and rods which connect the bowl cover to the carburetor body.
    2.  
    3. Remove the screws retaining the bowl cover.
    4.  
    5. Remove the bowl cover. Invert the bowl cover, taking care not to lose any of the small parts.
    6.  
    7. With the bowl cover inverted and the floats resting on the seated needle, measure the distance between the bowl cover (new gasket installed) to the bottom side of each float.
    8.  
    9. If not to specifications, bend the float lever.
    10.  

    Never allow the lip of the float to be pressed against the needle when adjusting the float height.

    1. Install the bowl cover. Make sure that the float pin does not protrude past the edge of the bowl cover.
    2.  

    MOTORCRAFT 2700 VV AND 710 VV

    See Figure 28

    1. Remove and invert the upper part of the carburetor, with the gasket in place.
    2.  
    3. Measure the vertical distance between the carburetor body (outside the gasket) and the bottom of the float.
    4.  
    5. To adjust, bend the float operating lever that contacts the needle valve. Make sure that the float remains parallel to the gasket surface.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 28: Motorcraft 2700/710 VV float level adjustment

    Float Drop
    MOTORCRAFT 2700 VV AND 710 VV

    See Figure 29

    1. Remove and hold upright the upper part of the carburetor.
    2.  
    3. Measure the vertical distance between the carburetor body (outside the gasket) and the bottom of the float.
    4.  
    5. Adjust by bending the stop tab on the float lever that contacts the hinge pin.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 29: Motorcraft 2700/710 VV float drop adjustment

    Dechoke Clearance

    CARTER YFA

    See Figure 30

    1. Remove the air cleaner assembly.
    2.  
    3. Hold the throttle plate fully open and close the choke plate as far as possible without forcing it. Use a drill bit of the proper diameter to check the clearance between the choke plate and air horn.
    4.  
    5. If the clearance is not within specification, adjust by bending the arm on the choke lever of the throttle lever. Bending the arm downward will decrease the clearance, and bending it upward will increase the clearance. Always recheck the clearance after making any adjustment.
    6.  



    Click image to see an enlarged view

    Fig. Fig. 30: Dechoke clearance adjustment-Carter YFA carburetor

    MOTORCRAFT 510 OR 6500

    Dechoke clearance cannot be adjusted. It is controlled by the fast idle cam settings.

    HOLLEY 1946

    See Figure 31

    1. Remove the air cleaner assembly.
    2.  
    3. With the engine off, hold the throttle in the wide open position.
    4.  
    5. Insert a drill bit of the specified diameter (as indicated in the Carburetor Specifications chart, later in this section), between the upper edge of the choke plate and the air horn wall.
    6.  
    7. With a slight pressure against the choke shaft, a slight drag should be felt when the gauge is withdrawn.
    8.  
    9. To adjust, bend the unloader tab on the throttle lever.
    10.  
    11. Install the air cleaner assembly, if no further adjustments are required at this time.
    12.  



    Click image to see an enlarged view

    Fig. Fig. 31: Dechoke clearance adjustment-Holley 1933 carburetor

    HOLLEY 4180
    1. Verify that the choke cap is set to the proper index mark, and adjust if necessary.
    2.  
    3. Hold the throttle in the wide open position.
    4.  
    5. Apply light closing pressure on the choke plate and measure the gap between the lower edge of the choke plate and the air horn wall.
    6.  
    7. If adjustment is necessary, bend the pawl on the fast idle lever.
    8.  

    MOTORCRAFT 4300, 4350
    1. Remove the air cleaner assembly.
    2.  
    3. Remove the automatic choke housing from the carburetor.
    4.  
    5. With the throttle plate wide-open and the choke plate closed as far as possible without forcing it, insert a drill gauge of the specified diameter between the choke plate and air horn.
    6.  
    7. To adjust, bend the arm on the choke trip lever. Bend downward to increase clearance and upward to decrease clearance. After adjusting, recheck the clearance.
    8.  
    9. Install the automatic choke housing, taking care to engage the thermostatic spring with the tang on the choke lever and shaft assembly.
    10.  
    11. Adjust the automatic choke setting. Install the air cleaner. Adjust the idle speed and dashpot, if so equipped.
    12.  

    Metering Rod
    CARTER YFA

    Remove the carburetor air horn and gasket from the carburetor. Unscrew the idle speed adjusting screw until the throttle plate is tightly closed in the throttle bore. Press downward on the end of the diaphragm shaft until the metering rod arm contacts the lifter link at the diaphragm stem. With the metering rod in this position, turn the rod adjustment screw until the metering rod just bottoms in the body casting. Turn the metering rod adjusting screw one additional turn in the clockwise direction. Install the carburetor air horn along with a new gasket.

    MOTORCRAFT 2700 VV AND 710 VV

    See Figure 32

    A dial indicator and the stator cap are required for this adjustment.

    1. Remove the choke coil cap, if equipped.
    2.  
    3. Attach a weight to the choke coil mechanism to seat the cold enrichment rod.
    4.  
    5. Install and zero a dial indicator with the tip placed on top of the enrichment rod. Raise and release the weight to verify zero on the dial indicator.
    6.  
    7. With the stator cap at the index position, the dial indicator should read the specified dimension. Turn the adjusting nut to correct it.
    8.  
    9. Install the choke cap at the correct setting.
    10.  



    Click image to see an enlarged view

    Fig. Fig. 32: Motorcraft 2700/7200 VV cold enrichment metering rod adjustment

    Accelerator Pump Stroke
    AUTOLITE/MOTORCRAFT 200, 42, 4100

    See Figure 33

    The accelerating pump operating rod should be in the over-travel lever hole number listed in the Carburetor Specification chart, and in the inboard hole (hole closest to the pump plunger) in the accelerating pump link. If the pump stroke has been changed from the specified settings, use the following procedure to correct the stroke:

    1. Release the operating rod from the retaining clip by pressing the tab end of the clip toward the rod while pressing the rod away from the clip until it disengages.
    2.  
    3. Position the clip over the specified hole (see Carburetor Specification chart) in the over-travel lever. Press the ends of the clip together and insert the operating rod through the clip and the over-travel lever. Release the clip to engage the rod.
    4.  



    Click image to see an enlarged view

    Fig. Fig. 33: Accelerator pump stroke adjustment-Autolite 2100, 2150, 4100

    AUTOLITE/MOTORCRAFT 4300

    The pump stroke is preset at the factory to limit exhaust emissions. The additional holes in the operating arm are provided for different engine applications. The stroke should not be changed from the specified hole (see Carburetor Specifications chart).

    The only adjustments possible are the pump stroke and pump stem height. To change the pump stroke, merely remove the pivot pin and reposition it in the specified hole. To adjust the pump stem height, bend the operating rod at the angles, taking care not to cause binds in the system.

    MOTORCRAFT 4350

    See Figure 34

    The accelerator pump adjustment is preset at the factory for reduced exhaust emissions. Adjustment is provided only for different engine installations. The adjustment is internal, with three piston-to-shaft pin positions in the pump piston.

    To check that the shaft pin is located in the specified piston hole, remove the carburetor air horn and invert it. Disconnect the accelerator pump from the operating arm by pressing downward on the spring and sliding the arm out of the pump shaft slot. Disassemble the spring and nylon keeper retaining the adjustment pin. If the pin is not in its specified hole, remove it, reposition the shaft to the correct hole in the piston assembly and reinstall the pin. Now slide the nylon retainer over the pin and position the spring on the shaft. Finally, compress the spring on the shaft and install the pump on the pump arm.

    Under no circumstances should you adjust the stroke of the accelerator pump by turning the vacuum limiter lever adjusting nut. This adjustment is preset at the factory and modification could result in poor cold driveability.



    Click image to see an enlarged view

    Fig. Fig. 34: Accelerator pump stroke adjustment-Motorcraft 4350

    HOLLEY 1946

    See Figure 35

    The accelerator pump stroke is pre-set at the factory and should not be adjusted in an effort to improve driveability. After disassembling the carburetor, be sure to return the accelerator pump operating link to its proper slot in the throttle return spring arm.

    1. Check the length of the accelerator pump operating link from its outside edge at the accelerator pump rod to its inside edge at the applicable slot. The measurement should be 2.140-2.142 in. (54-55mm) (1979-81) or 2.265-2.405 in. (42-61mm) (1982).
    2.  
    3. Adjust to the proper length, if necessary, by bending the loop in the operating link.
    4.  



    Click image to see an enlarged view

    Fig. Fig. 35: Accelerator pump stroke adjustment-Holley 1933

    Accelerating Pump Lever
    HOLLEY 4180
    1. Hold the primary throttle plates in the wide open position.
    2.  
    3. Using a feeler gauge, check the clearance between the accelerating pump operating lever adjustment screw head and the pump arm while depressing the pump arm with your finger.
    4.  
    5. To make an adjustment, loosen and hold the adjusting screw locknut and turn the adjusting screw inward to increase, or outward to decrease the adjustment. Keep in mind that a 1 / 2 turn will change the clearance by approximately 0.015 in. (0.261 mm). When the adjustment is complete, hold the adjusting screw stationary and tighten the locknut.
    6.  

    Throttle Positioner Clearance
    ALL CARBURETORS
    1. Check that the engine idle speed and mixture settings are correct and that the engine is at normal operating temperature.
    2.  
    3. Loosen the dashpot or solenoid locking nut.
    4.  
    5. With the throttle held closed, depress the plunger with a screwdriver blade and measure the clearance between the throttle lever and the plunger tip. If the clearance is not within specifications, turn the dashpot or solenoid until the proper clearance is obtained between the throttle lever and the plunger tip.
    6.  
    7. Tighten the locking nut and recheck the adjustment. Readjust if necessary.
    8.  

    Anti-Stall Dashpot
    ALL MODELS

    See Figure 36

    Make sure that the engine idle speed and mixture are correct and that the engine is at normal operating temperature. Loosen the anti-stall dashpot locknut (see accompanying illustration). With the throttle held closed, depress the plunger with a prytool and measure the clearance between the throttle lever and the plunger tip. If the clearance is not as specified in the Carburetor Specification charts, turn the dashpot until the proper clearance is obtained between the throttle lever and the plunger tip. After tightening the locknut, recheck the adjustment.



    Click image to see an enlarged view

    Fig. Fig. 36: Anti-stall dashpot adjustment

    Fast Idle Speed
    EXCEPT MOTORCRAFT 2700 VV and 710 VV

    See Figure 37

    Be sure that the curb idle speed and idle mixture are set to specification before adjusting the fast idle speed.

    1. Remove the air cleaner assembly, if necessary.
    2.  
    3. Place the transmission in NEUTRAL or PARK and bring the engine to normal operating temperature.
    4.  
    5. Turn OFF the ignition. If so equipped, set the A/C selector to the OFF position.
    6.  
    7. Disconnect the vacuum hose at the EGR valve and plug the hose.
    8.  
    9. If so equipped, disconnect the wire to the electric Ported Vacuum Switch (PVS).
    10.  
    11. Place the fast idle adjusting screw on the specified step of the fast idle cam.
    12.  
    13. Connect a suitable tachometer.
    14.  
    15. Start the engine without touching the accelerator pedal.
    16.  
    17. Adjust the fast idle speed to specification by turning the adjusting screw.
    18.  
    19. Rev the engine momentarily to allow the engine to return to idle and turn off the ignition.
    20.  
    21. Disconnect and remove the tachometer.
    22.  
    23. Remove the plug from the EGR vacuum hose and reconnect the hose.
    24.  
    25. If so equipped, reconnect the wire to the electric PVS.
    26.  
    27. Install the air cleaner assembly, if no further adjustments are required at this time.
    28.  



    Click image to see an enlarged view

    Fig. Fig. 37: Place the fast idle adjusting screw on the specified step of the fast idle cam before adjusting

    MOTORCRAFT 2700 VV AND 710 VV
    1. With the engine warmed up and idling, place the fast idle lever on the step specified on the engine compartment sticker or in the specifications chart. Disconnect and plug the EGR vacuum line.
    2.  
    3. Make sure the high speed cam positioner lever is disengaged.
    4.  
    5. Turn the fast idle speed screw to adjust to the specified speed.
    6.  

    Fast Idle Cam Index Setting

    CARTER YFA

    See Figure 38

    1. Position the fast idle screw on the second (kickdown) step of the fast idle cam, against the shoulder of the high step.
    2.  
    3. Apply light closing pressure on the choke plate.
    4.  
    5. Check the clearance between the lower edge of the choke plate and the air horn wall.
    6.  
    7. Adjust, if necessary, by bending the choke plate connecting rod.
    8.  



    Click image to see an enlarged view

    Fig. Fig. 38: Fast idle cam setting-Carter YFA carburetor

    1979 MOTORCRAFT 510 OR 6500

    See Figure 39

    1. Place the fast idle screw on the second (kickdown) step of the fast idle cam, against the shoulder of the top step.
    2.  
    3. Place a 5 / 16 in. drill bit between the lower edge of the choke plate and the air horn wall. Apply light closing pressure on the choke plate to hold the drill bit in place.
    4.  
    5. Measure the clearance between the tang on the choke lever and the arm on the fast idle cam. This measurement should be 0.010 in. (0.6mm) maximum.
    6.  
    7. If the clearance is out of specification, bend the choke lever tang to adjust.
    8.  



    Click image to see an enlarged view

    Fig. Fig. 39: Fast idle cam setting-1979 Motorcraft 5200 or 6500 carburetor

    1980-82 MOTORCRAFT 510 OR 6500
    1. Place the fast idle screw on the second (kickdown) step of the fast idle cam, against the shoulder of the top step.
    2.  
    3. Apply light downward pressure on the choke lever tang and, using the proper size drill bit (as indicated in the Carburetor Specifications chart, later in this section), check the clearance between the lower edge of the choke plate and the air horn wall.
    4.  
    5. If the clearance is out of specification, replace the choke lever. Do not attempt to bend the choke lever tang, since it is hardened.
    6.  

    HOLLEY 1946

    See Figure 40

    1. Position the fast idle adjusting screw on the second (kickdown) step of the fast idle cam, against the shoulder of the top step.
    2.  
    3. Apply light closing pressure on the choke plate.
    4.  
    5. Check the fast idle cam setting by placing a drill bit of the specified size (as indicated in the Carburetor Specifications chart, later in this section), between the upper edge of the choke plate and the air horn wall.
    6.  
    7. If necessary, bend the fast idle cam link to adjust.
    8.  



    Click image to see an enlarged view

    Fig. Fig. 40: Fast idle cam setting-Holley 1946 carburetor

    HOLLEY 4180
    1. Remove the spark delay valve, if so equipped, from the Distributor vacuum advance line, and route the vacuum line directly to the advance side of the distributor.
    2.  
    3. Trace the Exhaust Gas Recirculation (EGR) signal vacuum line from the EGR valve to the carburetor and if there is EGR/PVS valve or temperature vacuum switch located in the vacuum line routing, disconnect the EGR vacuum line at the EGR valve and plug the line.
    4.  
    5. If not equipped with an EGR/PVS valve or temperature vacuum switch do not detach the EGR vacuum line.
    6.  
    7. Trace the purge valve vacuum line from the purge valve located on the canister, to the first point where the vacuum line can be detached from the underhood hose routing. Disconnect the vacuum line at that point, cap the open port, and plug the vacuum line.
    8.  


    WARNING
    To prevent damage to the purge valve, do not disconnect the vacuum line at the purge valve.

    1. With the engine running at normal operating temperature, the choke plate fully opened and the manual transmission in NEUTRAL (or automatic transmission in PARK), place the fast idle lever on the second or kickdown step of the fast idle cam.
    2.  
    3. Adjust the fast idle screw to within 100 rpm of the speed specified on the Vehicle Emission Control Decal.
    4.  
    5. Reconnect all vacuum lines.
    6.  

    AUTOLITE/MOTORCRAFT 200 (1971-72 MODEL YEARS), 4100, 4300, 4350

    See Figure 41

    1. Loosen the choke housing retaining screws and position the housing 90ºs to the right.
    2.  
    3. Position the fast idle speed screw at the kickdown step of the fast idle cam. This kickdown step is identified by a small V stamped in the side of the casting.
    4.  
    5. Check the clearance between the lower edge of the choke plate and the wall of the air horn by inserting a drill of the specified diameter between them. Adjustment may be accomplished by turning the fast idle cam adjusting screw clockwise to increase or counterclockwise to decrease the clearance.
    6.  
    7. Set the choke housing to specifications, and adjust the anti-stall dashpot, idle speed, and mixture.
    8.  



    Click image to see an enlarged view

    Fig. Fig. 41: Fast idle cam index setting-Autolite 2100

    1973 AND LATER AUTOLITE/MOTORCRAFT 200, 42
    1. Loosen the choke thermostatic spring housing retaining screws and rotate the housing 90ºs in the rich direction.
    2.  
    3. Position the fast idle speed screw or lever on the high step of the cam.
    4.  
    5. Depress the choke pulldown diaphragm against the diaphragm stop screw thereby placing the choke in the pulldown position.
    6.  
    7. While holding the choke pulldown diaphragm depressed, slightly open the throttle and allow the fast idle cam to fall.
    8.  
    9. Close the throttle and check the position of the fast idle cam lever. When the fast idle cam is adjusted correctly, the screw should contact the V mark on the cam. Adjustment is accomplished by rotating the fast idle cam adjusting screw as needed.
    10.  

    MOTORCRAFT 2700 VV AND 710 VV

    See Figure 42

    A special tool is required for this job. Ford calls it a stator cap (#T77L-9834-A). It fits over the choke thermostatic lever when the choke cap is removed.

    1. Remove the choke coil cap. On 1980 and later California models, the choke cap is riveted in place. The top rivets will have to be drilled out. The bottom rivet will have to be driven out from the rear. New rivets must be used upon installation.
    2.  
    3. Place the fast idle lever in the specified step of the fast idle cam (the highest step is first) with the high speed cam positioner retracted.
    4.  
    5. If the adjustment is being made with the carburetor removed, hold the throttle lightly closed with a rubber band.
    6.  
    7. Turn the stator cap clockwise until the lever contacts the fast idle cam adjusting screw.
    8.  
    9. Turn the fast idle cam adjusting screw until the index mark on the cap lines up with the specified mark on the casting.
    10.  
    11. Remove the stator cap. Install the choke coil cap and set it to the specified housing mark.
    12.  



    Click image to see an enlarged view

    Fig. Fig. 42: Motorcraft 2700 and 7200 VV fast idle cam adjustment

    Control Vacuum

    This procedure applies only to the Motorcraft 2700 VV and 710 VV carburetors.

    1977 MODELS
    1. Make sure the idle speed is correct.
    2.  
    3. Using a 5 / 32 in. Allen wrench, turn the venturi valve diaphragm adjusting screw clockwise until the valve is firmly closed.
    4.  
    5. Connect a vacuum gauge to the vacuum tap on the venturi valve cover.
    6.  
    7. Idle the engine and use a 1 / 8 in. Allen wrench to turn the venturi bypass adjusting screw to the specified vacuum setting. You may have to correct the idle speed.
    8.  
    9. Turn the venturi valve diaphragm adjusting screw counterclockwise until the vacuum drops to the specified setting. You will have to work the throttle to get the vacuum to drop.
    10.  
    11. Reset the idle speed.
    12.  

    1980-82 MODELS

    This procedure applies only to the Motorcraft 2700 VV and 7200 VV carburetors.

    1. Remove the carburetor. Remove the venturi valve diaphragm plug with a center punch.
    2.  
    3. If the carburetor has a venturi valve bypass, remove it by unfastening the two cover retaining screw. Invert and remove the bypass screw plug from the cover with a drift. Install the cover.
    4.  
    5. Install the carburetor. Start the engine and allow it to reach normal operating temperature. Connect a vacuum gauge to the venturi valve cover. Set the idle speed to 500 rpm with the transmission in DRIVE.
    6.  
    7. Push and hold the venturi valve closed. Adjust the bypass screw to obtain a reading of 8 in. Hg (2 kPa) on the vacuum gauge. Make sure the idle speed remains constant. Open and close the throttle and check the idle speed.
    8.  
    9. With the engine idling, adjust the venturi valve diaphragm screw to obtain a reading of 6 in. Hg (1.5 kPa). Set the curb idle to specification. Install new venturi valve bypass and diaphragm plugs.
    10.  

    Throttle Positioner Clearance

    ALL CARBURETORS
    1. Check that the engine idle speed and mixture settings are correct and that the engine is at normal operating temperature.
    2.  
    3. Loosen the dashpot or solenoid locking nut.
    4.  
    5. With the throttle held closed, depress the plunger with a screwdriver blade and measure the clearance between the throttle lever and the plunger tip. If the clearance is not within specifications, turn the dashpot or solenoid until the proper clearance is obtained between the throttle lever and the plunger tip.
    6.  
    7. Tighten the locking nut and recheck the adjustment. Readjust if necessary.
    8.  

    Vacuum Operated Throttle Modulator

    HOLLEY 4180
    1. Set the parking brake, put the transmission in PARK or NEUTRAL and run the engine up to operating temperature.
    2.  
    3. Turn off the air conditioning and heater controls.
    4.  
    5. Disconnect and plug the vacuum hoses at the air control valve and EGR valve and purge control valve.
    6.  
    7. Place the transmission in the position specified on the underhood decal.
    8.  
    9. If necessary, check and adjust the curb idle rpm.
    10.  
    11. Place the transmission in NEUTRAL or PARK and rev the engine. Place the transmission in the specified position according to the underhood decal and recheck the curb idle rpm. Readjust if necessary.
    12.  
    13. Connect an external vacuum source which provides a minimum of 10 in. (68 kPa) of vacuum to the Vacuum Operated Throttle Modulator (VOTM) kicker.
    14.  
    15. Place the transmission in the specified position.
    16.  
    17. Adjust the throttle kicker (VOTM) locknut if necessary to obtain the proper idle rpm.
    18.  
    19. Reconnect all vacuum hoses.
    20.  

    Throttle and Downshift Linkage
    WITH MANUAL TRANSMISSION

    Throttle linkage adjustments are not normally required, unless the carburetor or linkage has been removed from the car or otherwise disturbed. In all cases, the car is first brought to operating temperature, with the choke open and the the fast idle adjusting screw off the fast idle cam. The idle speed is then set to specifications.Secondary Throttle Plate

    HOLLEY 4180
    1. Remove the carburetor from the engine.
    2.  
    3. Hold the secondary throttle plates closed.
    4.  
    5. Turn the secondary throttle shaft lever stop screw out until the secondary throttle plates seat in the throttle bores.
    6.  
    7. Turn the screw back in until the screw just touches the secondary lever, and then 1 / 4 additional turn.
    8.  

    Internal Vent

    This procedure applies only to the Motorcraft 2700 VV and 710 VV carburetors.

    It is required whenever the idle speed adjustment is changed.

    1. Make sure the idle speed is correct.
    2.  
    3. Place a 0.010 in. (0.6mm) feeler gauge between the accelerator pump stem and the operating link.
    4.  
    5. Turn the nylon adjusting nut until there is a slight drag.
    6.  

    Venturi Valve Limiter

    This procedure applies only to the Motorcraft 2700 VV and 710 VV carburetors.

    1. Remove the carburetor. Remove the venturi valve cover and the two rollers.
    2.  
    3. Use a center punch to loosen the expansion plug at the rear of the carburetor main body on the throttle side.
    4.  
    5. Use a suitable Allen wrench to remove the venturi valve wide open stop screw.
    6.  
    7. Hold the throttle wide-open.
    8.  
    9. Apply a light closing pressure on the venturi valve and check the gap between the valve and the air horn wall. To adjust, move the venturi valve to the wide-open position and insert an Allen wrench into the stop screw hole. Turn clockwise to increase the gap. Remove the wrench and check the gap again.
    10.  
    11. Install the wide open stop screw and turn it clockwise until it contacts the valve.
    12.  
    13. Push the venturi valve wide-open and check the gap. Turn the stop screw to bring the gap to specifications.
    14.  
    15. Reassemble the carburetor with a new expansion plug.
    16.  

    Control Vacuum Regulator (CVR)

    This procedure applies only to the Motorcraft 2700 VV and 710 VV carburetors.

    There are two systems used. The earlier system's CVR rod threads directly through the arm. The revised system, introduced in late 1977, has a 3 / 8 in. nylon hex adjusting nut on the CVR rod and a flange on the rod.

    EARLY SYSTEM
    1. Make sure that the cold enrichment metering rod adjustment is correct.
    2.  
    3. Rotate the choke coil cap half a turn clockwise from the index mark. Work the throttle to set the fast idle cam.
    4.  
    5. Press down lightly on the regulator rod. If there is no down travel, turn the adjusting screw counterclockwise until some travel is felt.
    6.  
    7. Turn the regulator rod clockwise with an Allen wrench until the adjusting nut begins to rise.
    8.  
    9. Press lightly on the regulator rod. If there is any down travel, turn the adjusting screw clockwise in 1 / 4 turn increments until it is eliminated.
    10.  
    11. Return the choke coil cap to the specified setting.
    12.  

    REVISED SYSTEM

    The cold enrichment metering rod adjustment must be checked and set before making this adjustment.

    1. After adjusting the cold enrichment metering rod, leave a dial indicator in place but remove the stator cap. Do not re-zero the dial indicator.
    2.  
    3. Press down on the CVR rod until it bottoms on its seat. Measure this amount of travel with the dial indicator.
    4.  
    5. If the adjustment is incorrect, hold the 3 / 8 in. CVR adjusting nut with a box wrench to prevent it from turning. Use an 11 / 32 in. Allen wrench to turn the CVR rod. Turning counterclockwise will increase the travel, and vice-versa.
    6.  

    High Speed Cam Positioner

    This procedure applies only to the Motorcraft 2700 VV and 710 VV carburetors.

    1. Place the high speed cam positioner in the specified cam step, counting the highest step as the first.
    2.  
    3. Place the fast idle lever in the corner of the positioner.
    4.  
    5. Hold the throttle firmly closed.
    6.  
    7. Remove the diaphragm cover. Adjust the diaphragm assembly clockwise until it lightly bottoms. Turn it counterclockwise 1 / 2 -1 1 / 2 turns until the vacuum port and diaphragm hole line up.
    8.  
    9. Install the cover.
    10.  

     
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