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    GM Camaro 1967-1981 Repair Guide

    Idle Speed and Mixture

    Print

    ADJUSTMENTS



    See Figures 1 through 14

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    Fig. Fig. 1: Identification of various components, including the idle speed and idle mixture screws, found on a typical Rochester Monojet® (one barrel)



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    Fig. Fig. 2: Identification of various components, including the idle speed and idle mixture screws, found on a typical Rochester Dualjet® (two barrel)



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    Fig. Fig. 3: Location of the idle solenoid adjustment screw and the idle mixture screws (one on each side) on a typical four barrel Holley® carburetor



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    Fig. Fig. 4: Location of the idle speed and idle mixture adjustment screws on a typical Rochester Quadrajet® (four barrel)



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    Fig. Fig. 5: Idle speed adjustment screw location and idle speed adjustment procedure-1976-79 Rochester® one barrel carburetor



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    Fig. Fig. 6: Idle speed adjustment procedure for 1976-78 6-cylinder engines



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    Fig. Fig. 7: Idle speed adjustment procedure for the 1977 four barrel carburetor equipped with a solenoid



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    Fig. Fig. 8: Idle speed adjustment for the 1977 four barrel carburetor without a solenoid



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    Fig. Fig. 9: Idle speed adjustment procedure for 1978-79 two barrel carburetors with solenoids



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    Fig. Fig. 10: Idle speed adjustment procedure for 1978-79 two barrel carburetors without solenoids



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    Fig. Fig. 11: Idle speed adjustment procedure for 1979-81 four barrel carburetors without solenoids



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    Fig. Fig. 12: Idle speed adjustment for 1979-81 four barrel carburetors with solenoids



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    Fig. Fig. 13: Idle speed adjustment for 1980 two barrel carburetors with solenoids



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    Fig. Fig. 14: Idle speed adjustment for 1980 two barrel carburetors without solenoids

    Idle mixture and speed adjustments are critical aspects of exhaust emission control. It is important that all tune-up instructions be carefully followed to ensure satisfactory engine performance and minimum exhaust pollution. The different combinations of emission systems application on the different engine models have resulted in a great variety of tune-up specifications. See the Tune-Up Specifications Chart at the beginning of this section. Beginning in 1968, all models have a decal conspicuously placed in the engine compartment giving tune-up specifications.

    When adjusting a carburetor with two idle mixture screws, adjust them alternately and evenly, unless otherwise stated.

    See Driveability And Emission Controls for illustrations and adjustment specifications of Carter and Rochester carburetors. In the following adjustment procedures the term "lean roll" means turning the mixture adjusting screws in (clockwise) from optimum setting to obtain an obvious drop in engine speed (usually 20 rpm).

    1967 Models Without Air Conditioning

    Adjust with air cleaner removed.

    1. Remove the air cleaner.
    2.  
    3. Connect a tachometer and vacuum gauge to the engine, set the parking brake, and place the transmission in Neutral.
    4.  
    5. Turn in the idle mixture screws until they [cf2]gently seat, then back out 1 1 / 2 turns.
    6.  
    7. Start the engine and allow it to come to the normal operating temperature. Make sure the choke is fully open, then adjust the idle speed screw to obtain the specified idle speed (automatic in Drive, manual in Neutral).
    8.  
    9. Adjust the idle mixture screw(s) to obtain the highest steady vacuum at the specified idle speed, except for the Rochester BV. For this carburetor, adjust the idle mixture screw out 1 / 4 turn from lean "drop-off," the point where a 20-30 rpm drop is achieved by leaning the mixture.
    10.  

    On carburetors having a hot idle compensator valve (A/C models,) hold the brass valve down with a thin, wooden tool while making the mixture adjustment.

    1. Repeat Steps 4 and 5 if necessary.
    2.  
    3. Turn off the engine, remove the gauges, and install the air cleaner.
    4.  

    1967 Models With Air Conditioning

    Adjust with the air cleaner removed.

    During this adjustment, air conditioning should be turned OFF on 327 and 350 cu in. engines.

    1. Remove the air cleaner.
    2.  
    3. Connect a tachometer and a vacuum gauge to the engine, set the parking brake, and place the transmission in Neutral.
    4.  
    5. Turn in the idle mixture screw(s) until they [cf2]gently seat, then back them out three turns.
    6.  
    7. Start the engine and allow it to reach normal operating temperature. Make sure the choke is fully open, then adjust the idle speed screw(s) to obtain the specified idle speed (automatic in Drive, manual in Neutral).
    8.  
    9. Turn the idle mixture screw(s) clockwise (in) to the point where a 20-30 rpm drop in speed is achieved-this is the lean "drop off" point. Back out the screws 1 / 4 turn from this point.
    10.  
    11. Repeat Steps 4 and 5, if necessary.
    12.  
    13. Turn off the engine, remove the gauges, and install the air cleaner.
    14.  

    1968-69 Models

    Adjust with the air cleaner installed.

    Turn off the air conditioner (if applicable) unless your car is a 1968 model with the 6 cylinder engine and automatic transmission. These cars should have the air conditioner turned ON when setting the idle.

    1. Turn in the idle mixture screw(s) until they seat gently, then back them out three complete revolutions.
    2.  
    3. Start the engine and allow it to reach operating temperature. Make sure the choke is fully open and the preheater valve is open, then adjust the idle speed screw to obtain the specified idle speed (automatic in Drive, manual in Neutral).
    4.  
    5. Adjust the idle mixture screw(s) to obtain the highest steady idle speed, then readjust the idle speed screw to obtain the specified speed. On cars with an idle stop solenoid adjust as follows:
      1. Adjust the idle speed to 500 rpm (6 cylinder) or 600 rpm (1968 V8) by turning the hex on the solenoid plunger. Refer to the tune-up decal in the engine compartment for 1969 idle speeds.
      2.  
      3. Disconnect the wire at the solenoid. This allows the throttle lever to seat against the idle screw.
      4.  
      5. Adjust the idle screw to obtain 400 rpm (1968), then reconnect the wire. On 1969 models, adjust the idle to that specified on the tune-up decal in the engine compartment.
      6.  

    6.  
    7. Adjust one mixture screw to obtain a 20 rpm drop in idle speed, and back out the screw 1 / 4 turn from this point.
    8.  
    9. Repeat Steps 3 and 4 for the second mixture screw (if so equipped).
    10.  
    11. Readjust the idle speed to obtain the specified idle speed.
    12.  

    1970 Models

    Adjust with the air cleaner installed.

    1. Disconnect the fuel tank line from the vapor canister (EEC).
    2.  
    3. Connect a tachometer to the engine, start the engine and allow it to reach operating temperature. Make sure the choke and preheater valves are fully open.
    4.  
    5. Turn off the air conditioner and set the parking brake. Disconnect and plug the distributor vacuum line.
    6.  
    7. Make the following adjustments:
    8.  

    6-250 ENGINE
    1. Turn in the mixture screw until it [cf2]gently seats, then back out the screw four complete revolutions.
    2.  
    3. Adjust the solenoid screw to obtain 830 rpm for manual transmissions (in Neutral) or 630 rpm for automatic transmissions (in Drive).
    4.  
    5. Adjust the mixture screw to obtain 750 rpm for manual transmissions (in Neutral) or 600 rpm for automatic transmissions (in Drive).
    6.  
    7. Disconnect the solenoid wire and set the idle speed to 400 rpm, then reconnect it.
    8.  
    9. Reconnect the distributor vacuum line.
    10.  

    V8-307 ENGINE
    1. Turn in the mixture screws until they seat [cf2]gently, then back them out four complete revolutions.
    2.  
    3. Adjust the carburetor idle speed screw to obtain 800 rpm for manual transmissions (in Neutral), or adjust the solenoid screw to obtain 630 rpm for automatic transmissions (in Drive).
    4.  
    5. Adjust both mixture screws equally inward to obtain 700 rpm for manual transmissions, 600 rpm for automatic transmissions (in Drive).
    6.  
    7. On cars with automatic transmissions, disconnect the solenoid wire, set the carburetor idle screw to obtain 450 rpm and reconnect the solenoid.
    8.  
    9. Reconnect the distributor vacuum line.
    10.  

    V8-350 (250 HP) ENGINE
    1. Turn in the mixture screws until they [cf2]gently seat, then back them out four complete revolutions.
    2.  
    3. Adjust the solenoid screw to obtain 830 rpm for manual transmissions (in Neutral), or 630 rpm for automatic transmissions (in Drive).
    4.  
    5. Adjust both mixture screws equally inward to obtain 750 rpm for manual transmissions or 600 rpm for automatics (in Drive).
    6.  
    7. Disconnect the solenoid wire, set the carburetor idle screw to obtain 450 rpm, and reconnect the solenoid.
    8.  
    9. Reconnect the distributor vacuum line.
    10.  

    V8-350 (300 HP) ENGINE
    1. Turn in both mixture screws until they [cf2]gently seat, then back them out four complete revolutions.
    2.  
    3. Adjust the carburetor idle screw to obtain 775 rpm for manual transmissions, 630 rpm for automatics (in Drive).
    4.  
    5. Adjust the mixture screws equally to obtain 700 rpm for manual transmissions, 600 rpm for automatics (in Drive).
    6.  
    7. Reconnect the distributor vacuum line.
    8.  

    V8-350 (360 HP Z28) ENGINE
    1. Set the mixture screws to obtain maximum idle rpm and adjust the idle speed screw to obtain 750 rpm in Neutral.
    2.  

    V8-396 (350 HP) ENGINE
    1. Turn in both mixture screws until they [cf2]gently seat, then back them out four complete revolutions.
    2.  
    3. Adjust the carburetor idle screw to obtain 700 rpm for manual transmissions or 630 rpm for automatics (in Drive).
    4.  
    5. For cars with automatic transmissions: adjust the mixture screws equally to obtain 600 rpm with the transmission in Drive.
    6.  
    7. For cars with manual transmissions: turn in [cf2]one mixture screw until the speed drops to 400 rpm, then adjust the carburetor idle screw to obtain 700 rpm. Turn in the [cf2]other mixture screw until the speed drops 400 rpm, then regain 700 rpm by adjusting the carburetor idle screw.
    8.  
    9. Reconnect the distributor vacuum line.
    10.  

    1971-72 Models

    [cf2]Adjust with air cleaner installed. The following initial idle adjustments are part of the normal engine tune-up. There is a tune-up decal placed conspicuously in the engine compartment outlining the specific procedure and settings for each engine application. Follow all of the instructions when adjusting the idle. These tuning procedures are necessary to obtain the delicate balance of variables for the maintenance of both reliable engine performance and efficient exhaust emission control.

    All engines have limiter caps on the mixture adjusting screws. The idle mixture is preset and the limiter caps installed at the factory in order to meet emission control standards. Do not remove these limiter caps unless all other possible causes of poor idle condition have been thoroughly checked out. The solenoid used on 1971 carburetors is different from the one used on earlier models. The Combination Emission Control System (C.E.C.) solenoid valve regulates distributor vacuum as a function of transmission gear position.


    CAUTION
    The C.E.C. solenoid is adjusted only after: 1) replacement of the solenoid, 2) major carburetor overhaul, or 3) after the throttle body is removed or replaced.

    All initial adjustments described below are made:

    1. With the engine warmed up and running.
    2.  
    3. With the choke fully open.
    4.  
    5. With the fuel tank line disconnected from the Evaporative Emission canister on all models.
    6.  
    7. With the vacuum hose disconnected at the distributor and plugged.
    8.  

    Be sure to reconnect the distributor vacuum hose and to reconnect the fuel tank-to-evaporative emission canister line or install the gas cap when idle adjustments are complete.

    6-250 ENGINE
    1. Adjust the carburetor idle speed screw to obtain 550 rpm (700 rpm for 1972) for manual transmissions (in Neutral) or 500 rpm (600 rpm for 1972) for automatics (in Drive). [cf2]Do not adjust the solenoid screw. Using the solenoid screw to set idle or incorrectly adjusting it may result in a decrease in engine braking.
    2.  
    3. Reconnect the vapor line and distributor vacuum advance line.
    4.  

    V8-307 AND 350 (2-BBL) ENGINES
    1. On 1971 models, adjust the carburetor idle speed screw to obtain 600 rpm for manual transmission (in Neutral) with the air conditioning turned OFF, or 550 rpm for automatic transmissions (in Drive) with the air conditioning turned ON. [cf2]Do not adjust the solenoid screw. On 1972 models, turn the air conditioning OFF and adjust the idle stop solenoid screw to obtain 900 rpm for manual transmissions (in Neutral) or 600 rpm for automatics (in Drive). Place the transmission in Park or Neutral and adjust the fast idle cam screw to get 1,850 rpm on 307 engines and 2,200 rpm on 350 engines.
    2.  
    3. Reconnect the vapor line and distributor vacuum advance line.
    4.  

    V8-350 (4-BBL EXCEPT Z28) ENGINE
    1. On 1971 models, adjust the carburetor idle speed screw to obtain 600 rpm for manual transmissions (in Neutral) with the air conditioning turned OFF, or 550 rpm for automatics (in Drive) with the air conditioning turned ON. [cf2]Do not adjust the solenoid screw. On 1972 models, turn the air conditioning OFF and adjust the idle stop solenoid screw to get 800 rpm for manual transmissions (in Neutral) or 600 rpm for automatic transmissions (in Drive).
    2.  
    3. For both 1971 and 1972 models, place the fast idle cam follower on the second step of the fast idle cam, turn the air conditioning OFF and adjust the fast idle to 1,350 rpm for manual transmissions (in Neutral) or 1,500 rpm for automatics (in Park).
    4.  
    5. Reconnect the vapor line and the distributor vacuum advance line on all models.
    6.  

    V8-350 (Z28) ENGINE

    On 1971 models, perform Steps 1-3. Perform Steps 4-5 for 1972 models.

    1. Adjust the mixture screws to obtain the maximum speed (rpm at idle), then adjust the carburetor idle speed screw to obtain 700 rpm (manual in Neutral and automatic in Drive).
    2.  
    3. Turn in one mixture screw to obtain a 20 rpm drop in speed, then back out 1 / 4 turn.
    4.  
    5. Repeat step 2 for the other mixture screw, then reset the idle to 700 rpm. [cf2]Do not adjust the solenoid screw.
    6.  
    7. On 1972 models, turn the air conditioning OFF and adjust the idle stop solenoid screw to obtain 900 rpm (in Neutral) for manual transmission and 700 rpm (in Drive) for automatic. Proceed with step 5.
    8.  
    9. Reconnect the vapor line and the distributor vacuum line.
    10.  

    V8-396 (CALLED 402 IN 1972) ENGINE
    1. On 1971 models, turn off the air conditioner and adjust the carburetor idle speed screw to obtain 600 rpm with manual transmissions in Neutral and automatics in Drive. [cf2]Do not adjust the solenoid screw. On 1972 cars, turn off the air conditioning and adjust the idle stop solenoid screw to 800 rpm (in Neutral) for manual transmissions and 600 rpm (in Drive) for automatics.
    2.  
    3. On both 1971 and 1972 cars, place the fast idle cam follower on the second step of the fast idle cam, turn off the air conditioner and adjust the fast idle to 1,350 rpm for manual transmissions (in Neutral) or 1,500 rpm for automatics (in Park).
    4.  
    5. Reconnect the vapor line and the distributor vacuum line on 1971 and 1972 cars.
    6.  

    1973 Models

    All models are equipped with idle limiter caps and idle solenoids. Disconnect the fuel tank line from the evaporative canister. The engine must be running at operating temperature, choke off, parking brake on, and rear wheels blocked. Disconnect the distributor vacuum hose and plug it. After adjustment, reconnect the vacuum and evaporative hoses.

    6-250 ENGINE

    Adjust the idle stop solenoid for 700 rpm on manual transmission models or 600 rpm on automatics (in Drive). On manual models, make no attempt to adjust the CEC solenoid (the larger of the two carburetor solenoids) or a decrease in engine braking could result.

    V8-307 & 350 (2-BBL) ENGINES
    1. With the air conditioning OFF, adjust the idle stop solenoid screw for a speed of 900 rpm on manual models; 600 rpm for automatics in Drive.
    2.  
    3. Disconnect the idle stop solenoid electrical connector and adjust the idle speed screw (screw resting on lower step of the cam) for 450 rpm on all 307 cu in. engines, 400 rpm on 350 engines with automatic transmissions, or 500 rpm on 350 cu in. engine with manual transmissions.
    4.  

    V8-350 (4-BBL) ENGINE
    1. Adjust the idle stop solenoid screw for 900 rpm on manual, 600 rpm on automatic (in Drive).
    2.  
    3. Connect the distributor vacuum hose and position the fast idle cam follower on the top step of the fast idle cam (turn air conditioning off) and adjust the fast idle to 1,300 rpm on manual transmission 350 engines; 1,600 rpm for all automatics in Park.
    4.  

    V8-350 (Z-28) ENGINE
    1. With the air conditioning OFF, adjust the idle stop solenoid screw to 900 rpm for the manual transmission; 700 rpm with the automatic transmission in Drive.
    2.  
    3. Connect the distributor vacuum hose and place fast idle cam follower on the top step of the fast idle cam. Adjust the fast idle to 1,300 rpm for manual transmission; and 1,600 rpm for automatic transmissions (in Park).
    4.  

    1974 Models

    The same preliminary adjustments as for 1973 apply.

    6-250 ENGINE
    1. Using the hex nut on the end of the solenoid body, turn the entire solenoid to get 850 rpm for the manual transmission; 600 rpm for automatic transmissions in Drive.
    2.  

    V8-350 (2-BBL) ENGINE
    1. Turn the air conditioning OFF. Adjust the idle stop solenoid screw for 900 rpm on manual; 600 rpm on automatic (in Drive).
    2.  
    3. De-energize the solenoid and adjust the carburetor idle cam screw (on low step of cam) for 400 rpm on automatic models (in Drive); 500 rpm on 350 engines with manual transmission.
    4.  

    V8-350 (4-BBL) ENGINE
    1. Turn the air conditioning OFF. Adjust the idle stop solenoid screw for 900 rpm on manual transmission models; 600 rpm on automatic (in Drive).
    2.  
    3. Connect the distributor vacuum hose. Position the fast idle cam follower on the top step of the fast idle cam and adjust the fast idle speed to 1,300 rpm on manual; 1,600 on automatic (in Park).
    4.  

    V8-350 (Z-28) ENGINE
    1. With the air conditioning OFF, adjust the idle stop solenoid screw for 900 rpm with the manual transmission; 700 with the automatic transmission in Drive.
    2.  
    3. Reconnect the distributor vacuum advance hose and place the fast idle cam follower on the top step of the fast idle cam. With the air conditioning OFF, adjust the fast idle to 1,300 rpm for manual transmissions; 1,600 rpm for all automatics in Park.
    4.  

    1975-76 Models

    6-250 (1-BBL) ENGINE
    1. Idle speed is adjusted with the engine at normal operating temperature, air cleaner on, choke open, and air conditioning OFF (air conditioning ON-1976 automatic transmission models). Hook up a tachometer to the engine.
    2.  
    3. Block the rear wheels and apply the parking brake.
    4.  
    5. Disconnect the fuel tank hose from the evaporative canister.
    6.  
    7. Disconnect and plug the distributor vacuum advance hose.
    8.  
    9. Start the engine and check the ignition timing. Adjust if necessary. Reconnect the vacuum hose. To adjust the idle speed, turn the solenoid in or out to obtain the higher of the two specifications listed on the decal. With the automatic transmission in Drive or the manual transmission in Neutral, disengage the solenoid electrical connector and turn the 1 / 8 in. allen screw in the end of the solenoid body to the lower idle speed.
    10.  
    11. Place the shift lever in Drive on cars with automatic transmissions and have an assistant apply the brakes. On cars with manual transmissions, put it into Neutral.
    12.  
    13. Cut the tab off the mixture limiter cap, but don't remove the cap. Turn the screw counterclockwise until the highest idle speed is reached.
    14.  
    15. Set the idle speed to the higher of the two listed idle speeds by turning the solenoid in or out.
    16.  
    17. Check the tachometer and turn the mixture screw clockwise until the idle speed is at the lower of the two listed idle speeds.
    18.  
    19. Shut off the engine, remove the tachometer, and reconnect the carbon canister hose.
    20.  

    1975 8-350 (2-BBL) AND 1976 8-305 (2-BBL) ENGINES
    1. Idle speed is adjusted with the engine at normal operating temperature, air cleaner on, choke open, and air conditioning OFF. Hook up a tachometer to the engine.
    2.  
    3. Block the rear wheels and apply the parking brake.
    4.  
    5. Disconnect the fuel tank hose from the evaporative canister.
    6.  
    7. Disconnect and plug the distributor vacuum advance hose.
    8.  
    9. Start the engine and check the ignition timing. Adjust if necessary. Reconnect the vacuum hose.
    10.  
    11. Adjust the idle speed screw to the specified rpm. If the figures given in the "Tune-Up Specifications" chart differ from those on the tune-up decal, those on the decal take precedence. Automatic transmissions should be in Drive, manual transmissions should be in Neutral.
    12.  


    CAUTION
    Make doubly sure that the rear wheels are blocked and the parking brake applied.

    Adjust the idle speed to the higher of the two figures on the tune-up decal. Back out the two mixture screws equally until the highest idle is reached. Reset the speed, if necessary, to the higher one on the tune-up decal. Next, turn the screws in equally until the lower of the two figures on the decal is obtained.

    1. Shut off the engine, reconnect the hose to the evaporative canister, and remove the blocks from the wheels.
    2.  

    V8-350 (4-BBL) ENGINE

    1975 four-barrel carburetors are equipped with idle stop solenoids. There are two idle speeds, one with the solenoid energized and second with the solenoid de-energized. Both are set with the solenoid. The slower speed (solenoid de-energized) is necessary to prevent dieseling by allowing the throttle plates to close further than at a normal idle speed.

    1. Idle speed is set with the engine at normal operating temperature, air cleaner on, choke open, and air conditioning OFF. Hook up a tachometer to the engine.
    2.  
    3. Block the rear wheels and apply the parking brake.
    4.  
    5. Disconnect the fuel tank hose from the evaporative canister.
    6.  
    7. Disconnect and plug the distributor vacuum advance hose.
    8.  
    9. Start the engine and check the ignition timing. Adjust if necessary. Reconnect the vacuum hose.
    10.  
    11. Detach the electrical connector at the idle solenoid.
    12.  
    13. Set the transmission in Drive. Adjust the low idle speed screw for the lower of the two figures given for idle speed.
    14.  


    CAUTION
    Make sure that the drive wheels are blocked and the parking brake is applied.

    1. Reconnect the idle solenoid and open the throttle slightly to extend the solenoid plunger.
    2.  
    3. Turn the solenoid plunger screw in or out to obtain the higher of the two idle speed figures (this is normal curb-idle).
    4.  

    To adjust the mixture, break off the limiter caps. Make sure that the idle is at the higher of the two speeds listed on the decal. Turn the mixture screws out equally to obtain the highest idle. Reset the idle speed with the plunger screw if necessary. Turn the mixture screws in until the lower of the two figures on the decal is obtained.

    1. Shut off the engine, remove the blocks from the drive wheels, and reconnect the hose to the evaporative canister.
    2.  

    For 1976, the idle solenoid has been dropped. To adjust the idle, follow the preceding Steps 1-5. Skip Steps 6, 7, and 8, then follow Steps 9 and 10, adjusting the idle speed screw.

    1977 Models

    1. First satisfy all the following requirements:
    2.  

    A. Set parking brake and block drive wheels. B. Bring the engine to operating temperature. C. Remove the air cleaner for access, but make sure all hoses stay connected. D. Consult the Emission Control Information label under the hood, and disconnect and plug hoses as required by the instructions there. E. Connect an accurate tach to the engine.

    1. Set ignition timing as described earlier in this section.
    2.  
    3. Remove the cap(s) from the idle mixture screw(s). Remove caps carefully, to prevent bending these screws.
    4.  
    5. Turn in the screw(s) untill they seat [cf2]very lightly, then back the screw(s) out just far enough to permit the engine to run.
    6.  
    7. Put the automatic transmission in Drive.
    8.  
    9. Back out the screw(s) 1 / 8 turn at a time, going alternately from screw to screw after each 1 / 8 turn where there are two screws, until the highest possible idle speed is achieved. Then, set the idle speed as follows: 250 CID engine with manual transmission-950; with automatic-575; with automatic in California-640; with automatic used in high altitude area-650; 305 V8 with manual transmission-650; with automatic-550; standard 350 V8, manual transmission-800; standard 350 V8 with automatic-550; 350 V8, manual transmission, used in Z-28-900; 350 V8 automatic used in Z-28-750; 350 V8 used at high altitudes-650.
    10.  
    11. After setting the idle speed, repeat the mixture adjustment to ensure that mixture is at the point where highest idle speed is obtained. Then, if idle speed has increased, repeat idle speed adjustment of Step 6.
    12.  
    13. Now, turn screw(s) in, going evenly in 1 / 8 turn increments where there are two, until the following idle speeds are obtained: 250 CID engine with manual transmission-750; with automatic-550; with automatic in California-600; with automatic used in high altitude areas-600; 305 V8 with manual transmission-600; with automatic-500; standard 350 V8, manual transmission-700; standard 350 V8 with automatic-500; 350 V8 with manual transmission used in Z-28-800; 350 V8 with automatic used in Z-28-700; 350 V8 used at high altitudes-600.
    14.  
    15. Reset idle speed to the value shown on the engine compartment sticker, if that differs from the final setting in the previous step.
    16.  
    17. Check and adjust fast idle as described on the engine compartment sticker. See Driveability And Emission Controls .
    18.  
    19. Reconnect any vacuum hoses that were disengaged for the procedure, and install the air cleaner.
    20.  
    21. If idle speed has changed, reset according to the engine compartment sticker. Disconnect the tach.
    22.  

    1978-81 Models

    1978 and later models have sealed idle mixture screws; in most cases these are concealed under staked-in plugs. Idle mixture is adjustable only during carburetor overhaul, and requires the addition of propane as an artificial mixture enrichener.

    See the emission control label in the engine compartment for procedures and specifications not supplied here. Prepare the car for adjustment (engine warm, choke open, fast idle screw off the fast idle cam) as per the label instructions.

    1-BBL CARBURETORS
    1. Run the engine to normal operating temperature.
    2.  
    3. Make sure that the choke is fully opened.
    4.  
    5. Turn the A/C OFF and disconnect the vacuum line at the vapor canister. Plug the line.
    6.  
    7. Set the parking brake, block the drive wheels and place the transmission in Drive (AT) or Neutral (MT). Connect a tachometer to the engine according to the manufacturer's instructions.
    8.  
    9. Turn the solenoid assembly to achieve the solenoid-on speed.
    10.  
    11. Disconnect the solenoid wire and turn the 1 / 8 inch hex screw in the solenoid end, to achieve the solenoid-off speed.
    12.  
    13. Remove the tachometer, connect the canister vacuum line and shut off the engine.
    14.  

    2 AND 4-BBL. CARBURETORS-EXCEPT V8-350 ENGINES
    1. Run the engine to normal operating temperature.
    2.  
    3. Make sure that the choke is fully opened, turn the A/C OFF, set the parking brake, block the drive wheels and connect a tachometer to the engine according to the manufacturer's instructions.
    4.  
    5. Disconnect and plug the vacuum hoses at the EGR valve and the vapor canister.
    6.  
    7. Place the transmission in Park (AT) or Neutral (MT).
    8.  
    9. Disconnect and plug the vacuum advance hose at the distributor. Check and adjust the timing.
    10.  
    11. Connect the distributor vacuum line.
    12.  
    13. Manual transmission cars without A/C and without solenoid: place the idle speed screw on the low step of the fast idle cam and turn the screw to achieve the specified idle speed.
    14.  

    Cars with A/C: set the idle speed screw to the specified rpm. Disconnect the compressor clutch wire and turn the A/C ON. Open the throttle momentarily to extend the solenoid plunger. Turn the solenoid screw to obtain the specified rpm.

    Automatic transmission cars without A/C; manual transmission cars without A/C, solenoid-equipped carburetor: momentarily open the throttle to extend the solenoid plunger. Turn the solenoid screw to obtain the specified rpm. Disconnect the solenoid wire and turn the idle speed screw to obtain the slow engine idle speed.

    2 AND 4-BBL. CARBURETORS-V8-350 ENGINES
    1. Run the engine to normal operating temperature.
    2.  
    3. Set the parking brake and block the drive wheels.
    4.  
    5. Connect a tachometer to the engine according to the manufacturer's instructions.
    6.  
    7. Disconnect and plug the purge hose at the vapor canister. Disconnect and plug the EGR vacuum hose at the EGR valve.
    8.  
    9. Turn the A/C OFF.
    10.  
    11. Place the transmission in Park (AT) or Neutral (MT).
    12.  
    13. Disconnect and plug the vacuum advance line at the distributor. Check and adjust the timing.
    14.  
    15. Connect the vacuum advance line. Place the automatic transmission in Drive.
    16.  
    17. Manual transmission cars without A/C: adjust the idle stop screw to obtain the specified rpm. Cars with A/C: with the A/C OFF, adjust the idle stop screw to obtain the specified rpm. Disconnect the compressor clutch wire and turn the A/C ON. Open the throttle slightly to allow the solenoid plunger to extend. Turn the solenoid screw to obtain the solenoid rpm listed on the underhood emission sticker.
    18.  
    19. Connect all hoses and remove the tachometer.
    20.  

    See Figures 15 and 16

    Click image to see an enlarged view

    Fig. Fig. 15: HEI Plug Wire Resistance Chart



    Click image to see an enlarged view

    Fig. Fig. 16: Mechanical Valve Lifter Clearance

     
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