GM Cutlass RWD 1970-1987 Repair Guide

1970-74 4 bbl. Carburetor


  1. After marking sure that the dwell and timing are correct, remove the air cleaner and disconnect and plug the air cleaner hose at the intake manifold.
  3. Start the engine and let it warm up. Make sure the choke is open and the air conditioner is off. Set the parking brake and block the wheels.
  5. On 1973-74 models, disconnect and plug the vapor canister hoses. Disconnect the EGR valve and plug the hose on all models.
  7. Disconnect and plug the distributor vacuum hose at the distributor.
  9. On models without a throttle solenoid or vacuum actuator, turn the idle speed adjusting screw inward or outward to obtain the idle speed listed in the specifications.
  11. On models with a throttle solenoid or vacuum actuator, turn the solenoid plunger inward or outward to obtain the higher of the two idle speeds listed in the specifications. After this adjustment has been made, disconnect the electric lead from the solenoid or the vacuum hose from the vacuum actuator. Plug the vacuum hose after disconnecting it. On models with an automatic transmission, place the transmission in Park. Adjust the throttle stop screw to obtain an idle speed which corresponds to the lower of the two idle speeds listed in the specifications.
  13. To adjust the idle mixture, shut the engine off, break the tabs off the limiter caps and turn the idle mixture screws inward until they are lightly seated.

Idle mixture screws have been preset at the factory and capped. Remove the caps only in the case of major overhaul, throttle body removal, or when all other possible causes of poor idle condition have been thoroughly checked. If you find it necessary to adjust the idle mixture, have the CO concentration checked by a dealer or garage with a CO meter.

  1. Back out the idle mixture screws six full turns, then start the engine and adjust the screws equally to obtain the highest possible idle.
  3. If necessary, reset the idle speed to specifications with the idle speed screw or the idle solenoid.
  5. Install new idle limiter caps.