Chevrolet Nova/ChevyII 1962-1979

1971-72 Vehicles

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Adjustments should be performed on all models with the air cleaner installed.

The idle stop solenoid is no longer used, having been replaced by the combination emission control valve. This valve is energized through the transmission to increase idle speed under conditions of high-gear deceleration and to provide full vacuum spark advance during high-gear operation. The valve is deenergized at curb idle and in the lower gears to provide a retarded spark under these conditions, the result of which is lower hydrocarbon emission. The valve need not be adjusted unless the solenoid or throttle body is removed, or the carburetor is overhauled.

Idle limiter caps are installed on the mixture screws of the carburetors of all 1971 cars. Chevrolet does not recommend removing these caps and does not recommend adjusting the mixture. Adjusting the mixture without the proper test gear will result in hydrocarbon emission levels in excess of the specified minimum.

  1. Follow steps 1-3 of the 1970 procedure.
  2.  
  3. Make the following adjustments:
  4.  

6-250 ENGINES



  1. Adjust the carburetor idle speed screw to obtain 550 rpm for manual transmissions (in Neutral) or 500 rpm for automatics (in Drive). Do not adjust the solenoid screw.
  2.  
  3. Reconnect the vapor line and the distributor vacuum advance line.
  4.  

8-307 (200 HP) AND 350 (245 HP) ENGINES



  1. Adjust the carburetor idle speed screw to obtain 600 rpm for manual transmissions (in Neutral) with the air conditioner turned off or 550 rpm for automatics (in Drive) with the air conditioner turned on. Do not adjust the solenoid screw.
  2.  
  3. Reconnect the vapor line and the distributor vacuum advance line.
  4.  

8-350 (270 HP) ENGINES



  1. 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. Do not adjust the solenoid screw.
  2.  
  3. Place the fast idle cam follower on the second step of the fast idle cam, turn the air conditioner 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.
  6.  

 
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