AutoZone 1986 Mazda 323 1.6L MFI SOHC 4cyl | Repair Guides | Fuel System | Fuel System | Carburetor | AutoZone.com

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    1986 Mazda 323 1.6L MFI SOHC 4cyl

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    GM Cutlass RWD 1970-1987 Repair Guide

    Carburetor

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    IDENTIFICATION



    General Motors Rochester carburetors are identified by their model code. The first number indicates the number of barrels, while one of the last letters indicates the type of choke used. These are V for the manifold mounted choke coil, C for the choke coil mounted in the carburetor body, and E for electric choke, also mounted on the carburetor. Model codes ending in A indicate an altitude-compensating carburetor.

    PRELIMINARY CHECKS (ALL CARBURETORS)



    The following should be observed before attempting any adjustments.

    1. Thoroughly warm the engine. If the engine is cold, be sure that it reaches operating temperature.
    2.  
    3. Check the torque of all carburetor mounting nuts and assembly screws. Always check the intake manifold-to-cylinder head bolts. If air is leaking at any of these points, any attempts at adjustment will inevitably lead to frustration.
    4.  
    5. Check the manifold heat control valve (if used) to be sure that it is free.
    6.  
    7. Check and adjust the choke as necessary.
    8.  
    9. Adjust the idle speed and mixture. If the mixture screws are capped, don't adjust them unless all other causes of rough idle have been eliminated. If any adjustments are performed that might possibly change the idle speed or mixture, adjust the idle and mixture again when you are finished.
    10.  

    Before you make any carburetor adjustments make sure that the engine is in tune. Many problems which are thought to be carburetor-related can be traced to an engine which is simply out-of-tune. Any trouble in these areas will have symptoms like those of carburetor problems.

    Fast Idle
    1. The fast idle adjustment is made with the transmission in neutral. On 1976-77 models, disconnect and plug the distributor vacuum line.
    2.  
    3. Make sure the engine is fully warmed up, and the choke is in the wide-open position.
    4.  
    5. Place the fast idle lever on the high step of the fast idle cam.
    6.  
    7. To adjust, bend the fast idle lever until the specified fast idle speed if obtained.
    8.  

    Choke Coil Lever
    1. Place the fast idle speed screw on the highest step of the fast idle cam.
    2.  
    3. Hold the choke plate fully closed.
    4.  
    5. Insert a 0.120 in. (3.048mm) gauge through the hole in the arm on the choke housing and into the hole in the casting.
    6.  
    7. Bend the link to adjust.
    8.  

    Automatic Choke
    1. Place the fast idle cam follower on the high step of the cam.
    2.  
    3. Loosen the three retaining screws and rotate the cover counterclockwise until the choke plate just closes.
    4.  
    5. Align the index mark on the cover with the specified housing mark. Tighten the three screws.
    6.  

    Unloader
    1. Hold the throttle valve wide open.
    2.  
    3. Hold down the choke plate with your fingers and insert the specified gauge between the upper edge of the choke plate and the airhorn wall.
    4.  
    5. Bend the linkage tang to adjust.
    6.  

    Vacuum break
    1. On vehicles equipped with TAC air cleaners (1975 and later), plug the sensor's vacuum take-off port after removing the air cleaner.
    2.  
    3. Using an external vacuum source, apply vacuum to the vacuum break diaphragm until the plunger is fully seated.
    4.  
    5. After the plunger is seated, push the choke plate fully closed.
    6.  
    7. Holding the choke plate in this position, place the specified gauge between the lower edge (upper edge in 1976-80) of the choke valve and the airhorn wall.
    8.  
    9. If the measurement is not correct, bend the vacuum break rod.
    10.  

    Metering Rod
    1. Remove the top of the carburetor.
    2.  
    3. Back out the idle stop solenoid and rotate the fast idle cam so that the fast idle screw does not contact the cam.
    4.  
    5. With the throttle plate completely closed, make sure the power piston is all the way up.
    6.  
    7. Remove the gasket from the bowl gasket surface. Measure the distance between the bowl gasket surface and the lower surface of the metering rod holder, next to the metering rod.
    8.  
    9. To adjust, carefully bend the metering rod holder.
    10.  

    ADJUSTMENTS



    Model MV Carburetor
    FLOAT LEVEL
    1. Remove the top of the carburetor if you have not done so already.
    2.  
    3. Hold the float retainer in place and the float arm against the top of the float needle by pushing down on the top of the float arm at the outer end toward the float bowl casting.
    4.  
    5. Using an adjustable T - scale, measure the distance from the top of the float to the float bowl gasket surface. See the specifications chart for the proper measurement.
    6.  

    The float bowl gasket should be removed and the gauge held on the index point of the float for accurate measurement.

    1. Adjust the float level by bending the float arm up or down at the float arm junction.
    2.  

    FAST IDLE
    1. The fast idle adjustment is made with the transmission in neutral. On 1976-77 models, disconnect and plug the distributor vacuum line.
    2.  
    3. Make sure the engine is fully warmed up, and the choke is in the wide-open position.
    4.  
    5. Place the fast idle lever on the high step of the fast idle cam.
    6.  
    7. To adjust, bend the fast idle lever until the specified fast idle speed if obtained.
    8.  

    CHOKE COIL LEVER
    1. Place the fast idle speed screw on the highest step of the fast idle cam.
    2.  
    3. Hold the choke plate fully closed.
    4.  
    5. Insert a 0.120 in. (3.048mm) gauge through the hole in the arm on the choke housing and into the hole in the casting.
    6.  
    7. Bend the link to adjust.
    8.  

    AUTOMATIC CHOKE
    1. Place the fast idle cam follower on the high step of the cam.
    2.  
    3. Loosen the three retaining screws and rotate the cover counterclockwise until the choke plate just closes.
    4.  
    5. Align the index mark on the cover with the specified housing mark. Tighten the three screws.
    6.  

    UNLOADER
    1. Hold the throttle valve wide open.
    2.  
    3. Hold down the choke plate with your fingers and insert the specified gauge between the upper edge of the choke plate and the airhorn wall.
    4.  
    5. Bend the linkage tang to adjust.
    6.  

    VACUUM BREAK
    1. On vehicles equipped with TAC air cleaners (1975 and later), plug the sensor's vacuum take-off port after removing the air cleaner.
    2.  
    3. Using an external vacuum source, apply vacuum to the vacuum break diaphragm until the plunger is fully seated.
    4.  
    5. After the plunger is seated, push the choke plate fully closed.
    6.  
    7. Holding the choke plate in this position, place the specified gauge between the lower edge (upper edge in 1976-80) of the choke valve and the airhorn wall.
    8.  
    9. If the measurement is not correct, bend the vacuum break rod.
    10.  

    METERING ROD
    1. Remove the top of the carburetor.
    2.  
    3. Back out the idle stop solenoid and rotate the fast idle cam so that the fast idle screw does not contact the cam.
    4.  
    5. With the throttle plate completely closed, make sure the power piston is all the way up.
    6.  
    7. Remove the gasket from the bowl gasket surface. Measure the distance between the bowl gasket surface and the lower surface of the metering rod holder, next to the metering rod.
    8.  
    9. To adjust, carefully bend the metering rod holder.
    10.  

    Model 2GC, 2GV, 2GE Carburetors
    FAST IDLE SPEED

    The fast idle is set automatically when the curb idle and mixture is set.

    CHOKE ROD (FAST IDLE CAM)
    1. Turn in the idle cam stop screw, if any, until it just contacts the bottom step of the fast idle cam. Then turn the screw one full turn.
    2.  
    3. Place the idle screw on the second step of the fast idle cam against the shoulder of the high step.
    4.  
    5. Hold the choke valve closed and check the clearance between the upper edge of the choke valve and the airhorn wall.
    6.  
    7. Adjust the clearance by bending the tang on the choke lever.
    8.  

    INTERMEDIATE CHOKE ROD (CHOKE COIL LEVER)
    1. Remove the thermostatic cover coil, gasket, and inside baffle plate assembly.
    2.  
    3. Place the idle speed screw on the highest step of the fast idle cam.
    4.  
    5. Close the choke valve by pushing up on the intermediate choke lever.
    6.  
    7. The idle of the coil lever inside the choke housing must line up with the edge of a 0.120 in. (3.048mm) drill bit inserted into the hole inside the choke housing.
    8.  
    9. Adjust by bending the intermediate choke rod at the first bend from the bottom of the rod.
    10.  

    VACUUM BREAK
    1. Remove the air cleaner. Vehicles with a Thermac air cleaner should have the sensor's vacuum take-off port plugged.
    2.  
    3. Using an external vacuum source, apply vacuum to the vacuum break diaphragm until the plunger is fully seated. If the diaphragm has a bleed hole, tape it over.
    4.  
    5. When the plunger is seated, push the choke valve toward the closed position. For 1976 and older models, place the idle speed screw on the high step of the fast idle cam.
    6.  
    7. Holding the choke valve in the closed position, place the specified size gauge between the upper idle of the choke valve and the airhorn wall.
    8.  
    9. If the measurement is not correct, bend the vacuum break rod.
    10.  

    See Figures 1 and 2



    Click image to see an enlarged view

    Fig. Fig. 1: Intermediate choke rod adjustment - 2GV, 2GC, 2GE



    Click image to see an enlarged view

    Fig. Fig. 2: Primary vacuum break adjustment - 2GV, 2GC, 2GE

    AUXILIARY VACUUM BREAK
    1. Seat the auxiliary vacuum diaphragm by applying an outside source of vacuum. Tape over the vacuum bleed hole so the vacuum will not bleed down.
    2.  
    3. Place the idle speed screw on the high step of the fast idle cam.
    4.  
    5. Hold the choke toward the closed choke position.
    6.  
    7. Measure the distance between the upper edge of the choke valve and the airhorn wall.
    8.  
    9. Adjust by bending the auxiliary vacuum break rod at the bottom of the U - shaped bend. Remove the piece of tape from the auxiliary vacuum diaphragm.
    10.  

    CHOKE UNLOADER ADJUSTMENT
    1. Hold the throttle valves wide open.
    2.  
    3. Close the choke valve.
    4.  
    5. Bend the unloader tang to obtain the proper clearance between the upper edge of the choke valve and airhorn wall.
    6.  

    See Figures 3 and 4



    Click image to see an enlarged view

    Fig. Fig. 3: Vacuum break adjustment - 2GV, 2GC, 2GE



    Click image to see an enlarged view

    Fig. Fig. 4: Auxiliary vacuum break adjustment - 2GV, 2GE, 2GC

    CHOKE COIL ROD ADJUSTMENT
    1. Hold the choke valve completely open.
    2.  
    3. Disconnect the coil rod from the upper lever and push down on the rod to the end of its travel.
    4.  
    5. When the rod is all the way down, the top of the rod should line up with the bottom of the slotted hold in the choke valve linkage.
    6.  
    7. Adjust by bending the lever.
    8.  

    FLOAT LEVEL

    With the airhorn assembly upside down, measure the distance from the airhorn gasket to the lip at the toe of the float. Bend the float arm to adjust to specifications.

    FLOAT DROP

    Holding the airhorn assembly upright, measure the distance from the gasket to the lip or notch at the toe of the float. If correction is necessary, bend the float tang at the rear, next to the needle and seat.

    ACCELERATOR PUMP ROD
    1. Back out the idle speed screw and completely close the throttle valves.
    2.  
    3. Place the pump gauge across the sir horn ring.
    4.  
    5. With the T - scale set to the specified height, the lower leg of the gauge should just touch the top of the accelerator pump rod.
    6.  
    7. Bend the pump rod to adjust.
    8.  

    Check and adjust, if necessary, the pump rod clearance and curb idle speed before adjusting the bowl vent valve.

    See Figures 5 and 6



    Click image to see an enlarged view

    Fig. Fig. 5: Choke unloader adjustment - 2GV, 2GC, 2GE



    Click image to see an enlarged view

    Fig. Fig. 6: Choke coil rod adjustment - 2GV, 2GC, 2GE

    1. Remove the two bowl vent valve cover attaching screws in the top of the airhorn and remove the cover and gasket. Remove the bowl vent valve spring.
    2.  
    3. Place the idle speed screw on the second step of the fast idle cam next to the highest step. In this position, the bowl vent valve should just be closed.
    4.  
    5. If the vent valve is just closed with the idle the fast idle cam, rotate the fast idle cam so that the idle speed screw is on the next lower step. In this position, the vent valve should just begin to open.
    6.  
    7. If it is necessary to adjust the bowl vent valve, turn the adjustment screw in the top of the valve, to obtain the conditions mentioned in Steps 2 and 3.
    8.  

    See Figures 7, 8, 9, 10 and 11



    Click image to see an enlarged view

    Fig. Fig. 7: Float level measurement (metal float) - 2GC, 2GV, 2GE



    Click image to see an enlarged view

    Fig. Fig. 8: Float drop (metal float) - 2GC, 2GV, 2GE



    Click image to see an enlarged view

    Fig. Fig. 9: Float drop (plastic float) - 2GC, 2GV, 2GE



    Click image to see an enlarged view

    Fig. Fig. 10: Accelerator pump rod - 2GV, 2GC, 2GE



    Click image to see an enlarged view

    Fig. Fig. 11: Bowl vent valve adjustment - 2GV, 2GC, 2GE

    Model 2MC, M2MC, M2ME, E2ME Carburetors
    FLOAT LEVEL ADJUSTMENT

    See the illustration for float level adjustment for all carburetors. The E2ME procedure is the same except for adjustment (step 4 in the figure). For the E2ME only, if the float level is too high, hold the retainer firmly in place and push down on the center of the float to adjust.

    If the float level is too low on the E2ME, lift out the metering rods. Remove the solenoid connector screws. Turn the lean mixture solenoid screw in clockwise, counting the exact number of turns until the screw is lightly bottomed in the bowl. Then turn the screw out counterclockwise and remove it. Lift out the solenoid and connector. Remove the float and bend and arm up to adjust. Install the parts, installing the mixture solenoid screw in until the lightly bottomed, then turning it out the exact number of turns counted earlier.

    See Figures 12, 13, 14, 15 and 16



    Click image to see an enlarged view

    Fig. Fig. 12: Float level adjustment - 2MC, M2MC, E2ME



    Click image to see an enlarged view

    Fig. Fig. 13: Fast idle adjustment - 2MC, M2MC, E2ME



    Click image to see an enlarged view

    Fig. Fig. 14: Fast idle cam (choke rod adjustment) - 2MC, M2MC, E2ME

    FAST IDLE SPEED
    1. Place the fast idle lever on the high step of the fast idle cam.
    2.  
    3. Turn the fast idle screw out until the throttle valves are closed.
    4.  
    5. Turn the screw in to contact the lever, then turn it in the number of turns listed in the specifications. Check this preliminary setting against the sticker figure.
    6.  

    FAST IDLE CAM (CHOKE ROD)
    1. Adjust the fast idle speed.
    2.  
    3. Place the cam follower lever on the second step of the fast idle cam, holding it firmly against the rise of the high step.
    4.  
    5. Close the choke valve by pushing upward on the choke coil level inside the choke housing, or by pushing up on the vacuum break lever tang.
    6.  
    7. Gauge between the upper edge of the choke valve and the inside of the airhorn wall.
    8.  
    9. Bend the tang on the fast idle cam to adjust.
    10.  

    PUMP

    This adjustment is not required on E2ME carburetors used in conjunction with the computer controlled system.

    1. With the fast idle cam follower off the steps of the fast idle cam, back out the idle speed screw until the throttle valves are completely closed.
    2.  
    3. Place the pump rod in the proper hole of the lever.
    4.  
    5. Measure from the top of the choke valve wall, next to the vent stack, to the top of the pump stem.
    6.  
    7. Bend the pump lever to adjust.
    8.  

    CHOKE COIL LEVER ADJUSTMENT
    1. Remove the choke cover and thermostatic coil from the choke housing. On models with a fixed choke cover, drill out the rivets and remove the cover. A thermostat cover kit will be required for assembly.
    2.  
    3. Push up on the coil tank (counterclockwise) until the choke is closed. The top of the choke rod should be at the bottom of the slot in the choke valve lever. Place the fast idle cam follower on the high step of the cam.
    4.  
    5. Insert a 0.120 in. (3.048mm) plug gauge in the hole in the choke housing.
    6.  
    7. The lower edge of the choke coil lever should just contact the side of the plug gauge.
    8.  
    9. Bend the choke rod to adjust.
    10.  



    Click image to see an enlarged view

    Fig. Fig. 15: Pump adjustment - 2MC, M2MC, E2ME



    Click image to see an enlarged view

    Fig. Fig. 16: Choke coil rod adjustment - 2MC, M2MC, E2ME

    2MC LEAN/RICH VACUUM BREAK
    1. Place the cam follower on the highest step of the fast idle cam.
    2.  
    3. Seat the vacuum break diaphragm by using an outside vacuum source. Tape over the bleed hole, if any, under the rubber cover on the diaphragm.
    4.  
    5. Remove the choke cover and thermostatic coil and push up on the coil lever inside the choke housing until the tang on the vacuum break lever contacts the tang on the vacuum break plunger stem. Do not compress the bucking spring for lean adjustment. Compress the bucking spring for rich adjustment.
    6.  
    7. With the choke rod in the bottom of the slot in the choke lever, gauge between the upper edge of the choke valve and the inside wall of the airhorn.
    8.  
    9. Bend the link rod at the vacuum break plunger stem to adjust the rich setting. Bend the link rod at the opposite end of the diaphragm to adjust the lean setting.
    10.  

    FRONT/REAR VACUUM BREAK ADJUSTMENT

    MODELS THROUGH 1980



    1. Seat the front diaphragm, using an outside vacuum source. If there is an air bleed hole in the diaphragm, tape over it.
    2.  
    3. Remove the choke cover and coil. Rotate the inside coil lever counter-clockwise. On models with a fixed choke cover (riveted), push up on the vacuum break lever tang and hold it in position with a rubber band.
    4.  
    5. Check that the specified gap is present between the top of the choke valve and the airhorn wall.
    6.  
    7. Turn the front vacuum break adjusting screw to adjust.
    8.  
    9. To adjust the rear vacuum break diaphragm, perform Steps 1-3 on the rear diaphragm, but make sure that the plunger bucking spring is compressed and seated in Step 2. Adjust by bending the link at the bend nearest the diaphragm.
    10.  

    See Figures 17, 18, and 19



    Click image to see an enlarged view

    Fig. Fig. 17: Rich vacuum break setting - 2MC



    Click image to see an enlarged view

    Fig. Fig. 18: Lean vacuum break setting - 2MC



    Click image to see an enlarged view

    Fig. Fig. 19: Rear vacuum break adjustment - 1981-82 E2ME

    FRONT/REAR VACUUM BREAK ADJUSTMENT

    MODELS 1981 AND LATER



    On these models a choke valve measuring gauge J-26701 or equivalent is used to measure angle (degrees instead of inches).

    Make choke coil lever adjustment and fast idle adjustment. Do not remove rivets and choke cover to perform this adjustment. Use rubber band on vacuum break lever tang to hold choke valve closed (step 8).

    1. Remove vacuum break from carburetor.
    2.  
    3. Place bracket in a vise and using safety precautions , grind off the adjustment screw cap.
    4.  
    5. Reinstall vacuum break.
    6.  
    7. Place your degree scale and magnet in position.
    8.  
    9. Close the choke valve.
    10.  
    11. Make sure that the leveling bubble is centered and that the degree scale is at the specified angle, (see specs). Release the choke valve.
    12.  
    13. Seat vacuum diaphragm making sure that the vacuum reading is above 5 in. Hg.
    14.  
    15. Lightly close choke by pushing upward on the choke coil lever or vacuum break tang hold in position with a rubber band.)
    16.  
    17. Make sure plunger bucking spring (if used) is compressed and seated.
    18.  

    To adjust:
    1. Using 1 / 8 in. hex wrench, turn the screw in the rear cover until the bubble is centered.
    2.  
    3. Apply sealer (such as silicone sealant rtv rubber or equivalent) over the screw head to seal setting.
    4.  

    On delay models, plug end cover using an accelerator pump plunger cup - 2G type or equivalent. Seat vacuum diaphragm making sure vacuum is above 5 in. Hg. when reading the gauge. Remove the cup after adjustment.

    UNLOADER ADJUSTMENT
    1. With the choke valve completely closed, hold the throttle valves wide open.
    2.  
    3. Measure between the upper edge of the choke valve and airhorn wall.
    4.  
    5. Bend the tang on the fast idle lever to obtain the proper measurement.
    6.  

    See Figures 20, 21 and 22



    Click image to see an enlarged view

    Fig. Fig. 20: Front vacuum break adjustment - 1981-82 E2ME



    Click image to see an enlarged view

    Fig. Fig. 21: Vacuum break adjustment - 1983 and later E2ME



    Click image to see an enlarged view

    Fig. Fig. 22: Front vacuum break adjustment, 1983 and later E2ME

    AIR CONDITIONING IDLE SPEED-UP SOLENOID ADJUSTMENT

    See Figures 23 and 24

    1. With the engine at normal operating temperature and the air conditioning turned on but the compressor clutch lead disconnected, the solenoid should be electrically energized (plunger stem extended). Open the throttle slightly to allow the solenoid plunger to fully extend.
    2.  
    3. Adjust the plunger screw to obtain the specified idle speed.
    4.  
    5. Turn off the air conditioner. The solenoid plunger should move away from the tang on the throttle lever.
    6.  
    7. Adjust the curb idle speed with the idle speed screw, if necessary.
    8.  

    Do not adjust if carburetor is computer controlled.



    Click image to see an enlarged view

    Fig. Fig. 23: Unloader adjustment - 2MC, M2MC



    Click image to see an enlarged view

    Fig. Fig. 24: Air conditioning idle speed up solenoid adjustment - 2MC, M2MC

    Quadrajet Carburetor

    The Rochester Quadrajet carburetor is a two stage, four-barrel downdraft carburetor. It has been built in many variations designated as 4MC, 4MV, M4MC, M4MCA, M4ME, M4MEA, E4MC, and E4ME. See the beginning of the section for an explanation of these designations.

    The primary side for the carburetor is equipped with two primary bores and a triple venturi with plain tube nozzles. During off idle and part throttle operation, the fuel is metered through tapered metering rods operating in specially designed jets positioned by a manifold vacuum responsive piston.

    The secondary side of the carburetor contains two secondary bores. An air valve is used on the secondary side for metering control and supplements the primary bore.

    The secondary air valve operates tapered metering rods which regulate the fuel in constant proportion to the air being supplied.

    FAST IDLE SPEED
    1. Position the fast idle lever on the high step of the fast idle cam.
    2.  
    3. Be sure that the choke is wide open and the engine warm. Plug the EGR vacuum hose. Disconnect the vacuum hose to the front vacuum break unit, if there is one.
    4.  
    5. Make a preliminary adjustment by turning the fast idle screw out until the throttle valves are closed, then screwing it in the specified number of turns after it contacts the lever (see the carburetor specifications).
    6.  
    7. Use the fast idle screw to adjust the fast idle to the speed, and under the conditions, specified on the engine compartment sticker or in the specifications chart.
    8.  

    See Figures 25 and 26



    Click image to see an enlarged view

    Fig. Fig. 25: Fast idle adjustment - Quadrajet



    Click image to see an enlarged view

    Fig. Fig. 26: Choke rod (fast idle cam) adjustment - Quadrajet

    CHOKE ROD (FAST IDLE CAM)
    1. Adjust the fast idle and place the cam follower on the second step of the fast idle cam against the shoulder of the high step.
    2.  
    3. Close the choke valve by exerting counter-clockwise pressure on the external choke lever. Remove the coil assembly from the choke housing and push upon the choke coil lever.
    4.  
    5. Insert a gauge of the proper size between the upper edge of the choke valve and the inside airhorn wall.
    6.  
    7. To adjust, bend the tang on the fast idle cam. Be sure that the tang rests against the cam after bending.
    8.  

    PRIMARY (FRONT) VACUUM BREAK - THROUGH 1981
    1. Loosen the three retaining screws and remove the thermostatic cover and coil assembly from the choke housing through 1979.
    2.  
    3. Place the cam follower lever on the highest step of the fast idle cam through 1977.
    4.  
    5. Seat the front vacuum diaphragm using an outside vacuum source. If there is a diaphragm unit bleed hole, tape it over.
    6.  
    7. Push up on the inside choke coil lever until the tang on the vacuum break lever contacts the tang on the vacuum break plunger. On models with a fixed choke coil cover, push up on the vacuum break lever tang.
    8.  
    9. Place the proper size gauge between the upper edge of the choke valve and the inside of the airhorn wall.
    10.  
    11. To adjust, turn the adjustment screw on the vacuum break plunger lever.
    12.  
    13. Install the vacuum hose to the vacuum break unit.
    14.  

    PRIMARY (FRONT) VACUUM BREAK - 1982 AND LATER

    On these models a choke valve measuring gauge J-26701 or equivalent is used to measure angle (degrees instead of inches).

    1. Attach a rubber band to green tang of the intermediate choke shaft.
    2.  
    3. Open the throttle to allow choke valve to close.
    4.  
    5. Set up angle gauge and set to specification.
    6.  
    7. Retract the vacuum break plunger using a vacuum source. At least 18 in. Hg.
    8.  
    9. Plug the air bleed holes where applicable.
    10.  
    11. On Quadrajets, the air valve rod must not restrict the plunger from retracting fully.
    12.  
    13. If necessary, bend the rod to permit full plunger travel.
    14.  
    15. Final rod clearance must be set after the vacuum break setting has been made.
    16.  
    17. With the vacuum still applied, adjust the screw so that the bubble is centered on the measuring gauge.
    18.  

    See Figures 27 and 28



    Click image to see an enlarged view

    Fig. Fig. 27: Front vacuum break adjustment - Quadrajet through 1981



    Click image to see an enlarged view

    Fig. Fig. 28: Front vacuum break adjustment - Quadrajet 1982 and later

    SECONDARY (REAR) VACUUM BREAK - THROUGH 1980
    1. Remove the thermostatic cover and coil assembly from the choke housing through 1979.
    2.  
    3. Place the cam follower on the highest step of the fast idle cam through 1977.
    4.  
    5. Tape over the bleed hole in the rear vacuum break diaphragm and seat the diaphragm using an outside vacuum source. Make sure the diaphragm plunger bucking spring, if any is compressed. On delay models (1980), plug the end cover with a pump plunger cup or equivalent and remove after adjustment.
    6.  
    7. Close the choke by pushing up on the choke coil lever inside the choke housing. ON models with a fixed choke coil cover, push up on the vacuum break lever tang and use a rubber band to hold in place.
    8.  
    9. With the choke rod in the bottom of the slot in the choke lever, measure between the upper edge of the choke valve and the airhorn wall with a wire type gauge.
    10.  
    11. To adjust, bend the vacuum break rod at the first bend near the diaphragm except on 1980 models with the screw at the rear of the diaphragm; on those models, turn the screw to adjust.
    12.  
    13. Remove the tape covering the bleed hole of the diaphragm and connect the vacuum hose.
    14.  

    SECONDARY REAR VACUUM BREAK - 1981 and LATER

    On these models a choke valve measuring gauge J-26701 or equivalent is used to measure angle (degrees instead of inches).

    1. Place the cam follower on the highest step of the fast idle cam.
    2.  
    3. Seat the vacuum break diaphragm using an outside vacuum source.
    4.  
    5. Push up on the choke coil lever make sure that the diaphragm lever is pulled out until it is seated and that the bucking spring is compressed.
    6.  
    7. Make sure the rod is in the bottom of the slot.
    8.  
    9. Gauge between the air horn and wall and the upper edge of the choke valve.
    10.  

    See Figures 29 and 30



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    Fig. Fig. 29: Rear vacuum break adjustment (without adjustment screw) - Quadrajet through 1980



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    Fig. Fig. 30: Quadrajet rear vacuum break adjustment - 1981-82

    CHOKE UNLOADER
    1. Push up on the vacuum break lever to close the choke valve, and fully open the throttle valves.
    2.  
    3. Measure the distance from the upper edge of the choke valve to the airhorn wall.
    4.  
    5. To adjust, bend the tang on the fast idle lever.
    6.  

    CHOKE COIL ROD - 4MV
    1. Close the choke valve by rotating the choke coil lever counter-clockwise.
    2.  
    3. Disconnect the thermostatic coil rod from the upper lever.
    4.  
    5. Push down on the rod until it contacts the bracket of the coil.
    6.  
    7. The rod must fit in the notch of the upper lever.
    8.  
    9. If it does not, it must be bent on the curved portion just below the upper lever.
    10.  

    See Figures 31, 32 and 33



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    Fig. Fig. 31: Rear vacuum break adjustment - 1983 and later Quadrajet



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    Fig. Fig. 32: Unloader adjustment - Quadrajet



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    Fig. Fig. 33: Choke coil lever adjustment - Quadrajet (MC, ME)

    CHOKE COIL LEVER - MC & ME
    1. Remove the choke cover and thermostatic coil from the choke housing. On models with a fixed (riveted) choke cover, the rivets must be drilled out. A choke-stat kit is necessary for assembly. Place the fast idle cam follower on the high step.
    2.  
    3. Push up on the coil tank (counter-clockwise) until the choke valve is closed. The top of the choke rod should be at the bottom of the slot in the choke valve lever.
    4.  
    5. Insert a 0.120 in. (3.048mm) drill bit in the hole in the choke housing.
    6.  
    7. The lower edge of the choke coil lever should just contact the side of the plug gauge.
    8.  
    9. Bend the choke rod at the top angle to adjust.
    10.  

    SECONDARY CLOSING ADJUSTMENT

    This adjustment assures proper closing of the secondary throttle plates.

    1. Set the slow idle as per instructions in the appropriate car section. Make sure that the fast idle cam follower is not resting on the fast idle cam and the choke valve is wide open.
    2.  
    3. There should be 0.020 in. (0.508mm) clearance between the secondary throttle actuating rod and the front of the slot on the secondary throttle lever with the closing tang on the throttle lever resting against the actuating lever.
    4.  
    5. Bend the secondary closing tang on the primary throttle actuating rod or lever to adjust.
    6.  

    See Figures 34 and 35



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    Fig. Fig. 34: Secondary closing adjustment - Quadrajet



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    Fig. Fig. 35: Secondary opening adjustment (three point linkage) - Quadrajet

    SECONDARY OPENING ADJUSTMENT
    1. Open the primary throttle valves until the actuating link contacts the upper tang on the secondary lever.
    2.  
    3. With two point linkage, the bottom of the link should be in the center of the secondary lever slot.
    4.  
    5. With three point linkage, there should be 0.070 in. (1.778mm) clearance between the link and the middle tang.
    6.  
    7. Bend the upper tang on the secondary lever to adjust as necessary.
    8.  

    FLOAT LEVEL

    With the airhorn assembly removed, measure the distance from the airhorn gasket surface (gasket removed) to the top of the float at the two ( 1 / 16 in. back from the toe on 1975 models; 3 / 16 in. back on 1976 and later models).

    Make sure the retaining pin is firmly held in place and that the tang of the float is lightly held against the needle and seat assembly.

    Remove the float and bend the float arm to adjust except on carburetors used with the C-4 system (E4MC and E4ME). For those carburetors, if the float level is too high, hold the retainer firmly in place and push down on the center of the float to adjust. If the float level is too low on C-4 models, lift out the metering rods. Remove the solenoid connector screw. Turn the lean mixture solenoid screw in clockwise, counting and recording the exact number of turns until the screw is lightly bottomed in the bowl. Then turn the screw out clockwise and remove. Lift out the solenoid and connector. Remove the float and bend the arm up to adjust. Install the parts, turning the mixture solenoid screw in until it is lightly bottomed, then unscrewing it the exact number of turns counted earlier.

    See Figures 36 and 37



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    Fig. Fig. 36: Quadrajet float level adjustment



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    Fig. Fig. 37: Accelerator pump rod adjustment - Quadrajet

    ACCELERATOR PUMP

    The accelerator pump is not adjustable on C-4 carburetors (E4MC and E4ME).

    1. Close the primary throttle valves by backing out the slow idle screw and making sure that the fast idle cam follower is off the steps of the fast idle cam.
    2.  
    3. Bend the secondary throttle closing tang away from the primary throttle lever, if necessary, to insure that the throttle lever, if necessary, to insure the primary throttle valves are fully closed.
    4.  
    5. With the pump in the appropriate hole in the pump lever, measure from the top of the choke valve wall to the top of the pump stem.
    6.  
    7. To adjust, bend the pump lever.
    8.  
    9. After adjusting, readjust the secondary throttle tang and the slow idle screw.
    10.  

    See Figure 38



    Click image to see an enlarged view

    Fig. Fig. 38: Air valve spring adjustment - Quadrajet

    AIR VALVE SPRING ADJUSTMENT

    To adjust the air valve spring windup, loosen the Allen head lockscrew and turn the adjusting screw counter-clockwise to remove all spring tension. With the air valve closed, turn the adjusting screw clockwise the specified number of turns after the torsion spring contacts the pin on the shaft. Hold the adjusting screw in this position and tighten the lockscrew.

    REMOVAL & INSTALLATION



    See Figures 39, 40, 41, 42, 43, 44, 45 and 46

    All Carburetors
    1. Disconnect the negative battery cable. Remove the air cleaner and its gasket.
    2.  
    3. Tag and disconnect the fuel and vacuum lines from the carburetor.
    4.  
    5. Disconnect the choke coil rod, heated air line tube, or electrical connector.
    6.  
    7. Disconnect the throttle linkage.
    8.  
    9. On automatic transmission cars, disconnect the throttle valve linkage if so equipped.
    10.  
    11. If CEC equipped remove the CEC valve vacuum hose and electrical connector. Disconnect the EGR line, if so equipped.
    12.  
    13. Remove the idle stop solenoid, if so equipped.
    14.  
    15. Remove the carburetor attaching nuts and/or bolts, gasket or insulator, and remove the carburetor.
    16.  

    To install:
    1. Install the carburetor. Use a new gasket and fill the float bowl with gasoline to ease starting the engine.
    2.  
    3. Connect the idle stop solenoid, EGR line and CEC valve vacuum hose (if equipped)
    4.  
    5. Connect the throttle linkage and the automatic transmission throttle valve linkage (if equipped)
    6.  
    7. Connect the choke coil rod, heated air line tube, or electrical connector.
    8.  
    9. Connect the fuel and vacuum lines.
    10.  
    11. Install the air cleaner, negative battery cable and check for leaks.
    12.  

    Tag and mark all fuel lines, vacuum lines and electrical connections before removal



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    Fig. Fig. 39: Tag and mark all fuel lines, vacuum lines and electrical connections before removal



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    Fig. Fig. 40: Remove the small clip retaining the throttle cable



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    Fig. Fig. 41: Remove the fuel line from the carburetor



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    Fig. Fig. 42: Remove the fuel filter assembly. Be careful of dripping fuel.



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    Fig. Fig. 43: Remove the carburetor attaching bolts



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    Fig. Fig. 44: Remove the carburetor base attaching bolts



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    Fig. Fig. 45: Remove the carburetor from the vehicle



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    Fig. Fig. 46: Remove and discard old gasket, always use a new gasket during reassembly

    OVERHAUL



    All Types

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

    Overhaul your carburetor in a clean, dust free area. Carefully disassemble the carburetor, referring often to the exploded views and directions packaged with the rebuilding kit. Keep all similar and look-alike parts segregated during 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 then 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 or 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 an choke shaft bores for wear or an out-of-round conditions. 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; wear may allow air leakage, which could affect starting and idling.
    6.  

    Throttle shafts and bushings are not included in overhaul kits. They 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. Test the accelerator pump check valves. They should pass air one way but not the other. Test for proper seating by blowing and sucking on the valve. Replace the valve check ball and spring as necessary. If the valve is satisfactory, wash the valve parts again to remove breath moisture.
    4.  
    5. Check the bowl cover for warped surfaces with a straightedge.
    6.  
    7. Closely inspect the accelerator pump plunger wear and damage, replacing as necessary.
    8.  
    9. After the carburetor is assembled, check the choke valve for freedom of operation.
    10.  

    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:
    1. All gaskets
    2.  
    3. Float needle valve
    4.  
    5. All diagrams
    6.  
    7. Spring for the pump diaphragm
    8.  

    Major Repair Kits:
    1. All jets and gaskets
    2.  
    3. All diaphragms
    4.  
    5. Float needle valve
    6.  
    7. Pump ball valve
    8.  
    9. Float
    10.  
    11. Complete intermediate rod
    12.  
    13. Intermediate pump lever
    14.  
    15. Some cover hold-down screws and washers
    16.  

    Gasket Kits:
    1. All gaskets
    2.  

    After cleaning and checking all components, reassembly the carburetor, using new parts and referring to the exploded view. When reassembling, make sure that all screws and jets are tight in their seats, but do not overtighten as the tips 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.

     
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