Chevrolet Nova/ChevyII 1962-1979

1968-69 Vehicles

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Adjustments should be performed on all models with the air cleaner installed. On air-conditioned models, the idle speed and air/fuel mixture should be set with the air conditioning unit turned off, except for those models equipped with four- or six-cylinder engines, or the 325 hp/327 cu in. V8. On these engines, adjustments should be performed with the air conditioner turned on.

  1. Turn in the idle mixture screw(s) until they seat gently, then back them out three turns.
  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 having an idle stop solenoid, adjust as follows:
  6.  
    1. Adjust idle speed to 500 rpm (L-6) or 600 rpm (V8) by turning the hex on the solenoid plunger;
    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, then reconnect the wire.
    6.  

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

 
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