Chevrolet Nova/ChevyII 1962-1979

1970 Vehicles

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

  1. Disconnect the "fuel tank" line from the vapor canister (EEC).
  2.  
  3. Connect a tachometer to the engine, start the engine, and allow it to reach operating temperature. Make sure the choke and preheater valves are fully open.
  4.  
  5. Turn off the air conditioner and set the parking brake. Disconnect and plug the distributor vacuum line.
  6.  
  7. Make the following adjustments:
  8.  

4-153 ENGINES



  1. Set the mixture screw to obtain the maximum idle rpm;
  2.  
  3. Adjust the idle speed screw to obtain 750 rpm for manual transmissions (in neutral), 650 rpm for automatics (in Drive);
  4.  
  5. Adjust the mixture screw to obtain a 20 rpm drop in idle speed, then back it out 1 / 4 turn from this point;
  6.  
  7. Readjust the idle speed to obtain the specified rpm, then reconnect the vacuum line.
  8.  

6-230/250 ENGINES



  1. Turn in the mixture screw until it gently seats, then back out the screw four turns.
  2.  
  3. Adjust the solenoid screw to obtain 830 rpm for manual transmissions (in neutral) or 630 rpm for automatics (in Drive).
  4.  
  5. Adjust the mixture screw to obtain 750 rpm for manual transmission (in neutral) or 600 rpm for automatics (in Drive).
  6.  
  7. Disconnect the solenoid wire and set the idle speed to 400 rpm, then reconnect the wire).
  8.  
  9. Reconnect the distributor vacuum line.
  10.  

8-307 ENGINES



  1. Turn in the mixture screws until they seat gently, then back them out four turns.
  2.  
  3. Adjust the carburetor idle speed screw to obtain 800 rpm for manual transmissions (in neutral), or adjust the solenoid screw to obtain 630 rpm for automatic transmissions (in Drive).
  4.  
  5. Adjust both mixture screws equally, inward, to obtain 700 rpm for manual transmissions; 600 rpm for automatics (in Drive).
  6.  
  7. On cars with automatic transmissions, disconnect the solenoid wire, set the carburetor idle screw to obtain 450 rpm, and reconnect the solenoid.
  8.  
  9. Reconnect the distributor vacuum line.
  10.  

8-350 (300 HP) ENGINES



  1. Turn in both mixture screws until they gently seat, then back them out four turns.
  2.  
  3. Adjust the carburetor idle screw to obtain 775 rpm for manual transmissions; 630 rpm for automatics (in Drive).
  4.  
  5. Adjust the mixture screws equally to obtain 700 rpm for manual transmissions; 600 rpm for automatics (in Drive).
  6.  
  7. Reconnect the distributor vacuum line.
  8.  

  1. Disconnect the tachometer and reconnect the fuel vapor line.
  2.  

 
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