GM Cutlass RWD 1970-1987 Repair Guide

1970-74 2 bbl. Carburetor


  1. After making 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 if off. Set the parking brake and block the drive wheels.
  5. Disconnect the hoses from the vapor canister and plug them. Disconnect the EGR valve hose if the car has an EGR valve and plug it. 1973 and later cars will have an EGR valve.
  7. Disconnect the vacuum advance line from the distributor and plug it.
  9. 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 tune-up chart. 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. If the car is equipped with an automatic transmission, place the transmission in Park. Adjust the throttle stop screw to obtain an idle speed which corresponds with the lower of the two idle speeds listed in the tune-up specifications chart.
  11. To adjust the idle mixture, turn the engine off and turn the idle mixture screws inward until they are lightly seated.
  13. Back out the mixture screws six full turns and then start the engine.
  15. With the engine running, adjust the screws equally to obtain the highest possible idle speed.

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. Reset the idle speed to specifications with the idle speed screw or the idle solenoid.
  3. Install new idle limiter caps.