Article 938 - High or Erratic Engine Idle Speed

TSB #50 - November 4, 1966
(All 1967 390-2V Engine Equipped Units)

Customers may complain of high or erratic engine idle speed on subject units which normal idle adjustments will not correct. This complaint may be caused by throttle plate to throttle bore interference limiting full return of the throttle plates. This problem cause can be corrected by properly locating the throttle plates on the throttle shaft using the following procedure:
    1. Remove the carburetor air cleaner, air horn and gasket.
    2. Remove the booster venturi assembly.
    3. Remove the accelerator pump discharge weight and reinstall the booster support screw to retain the check ball.
    4. Loosen the four throttle plate bolts 1/2 turn using a 1/4 inch midget socket set (Illus. S1141).
    5. Turn the idle speed adjusting screw three turns counterclockwise to allow the throttle plates to fully close. (Be sure the choke fast idle cam does not interfere).
    6. Rotate the throttle shaft a few times and return it to the closed position.
    7. Lightly tap the throttle plates to insure proper positioning and tighten the throttle plate attaching bolts. CAUTION: Tighten the outer throttle plate bolts first.
    8. Remove the booster support screw and install the discharge weight and booster venturi.
    9. Install the carburetor air horn and gasket.
    10. Turn the idle speed adjusting screw clockwise three turns to its original position.
    11. Readjust the engine idle speed and idle fuel mixture and install the air cleaner to complete this corrective procedure.

Oper: SP-9510-A-67
Time: 0.3 hrs.