GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Carter AVS 4-BBL Carburetor

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AIR VALVE ADJUSTMENT



  1. Turn the air valve bearing retainer until the air valve freely falls open.
  2.  
  3. Wind the air valve bearing counterclockwise until the air valve just starts to close.
  4.  
  5. Continue to wind the bearing an additional 2 1 / 8 turns, and then tighten the retainer.
  6.  

ACCELERATOR PUMP ADJUSTMENT



  1. With the fast idle cam out of the way, back the idle speed screw out until the throttle valves seat in their bores.
  2.  
  3. Hold the throttle valves closed and measure the distance from the air horn to the bottom of the pump S-link.
  4.  
  5. If this distance is not 11 / 16 in., bend the pump rod to obtain a proper measurement.
  6.  

IDLE VENT ADJUSTMENT



Holding the choke valve open and the throttle valve closed, the clearance at the idle vent valve should be 0.030 in. (0.762mm). Bend the vent valve lever, as necessary, to adjust.

FAST IDLE CHOKE ROD ADJUSTMENT



Bend the fast idle rod at a lower angle until the fast idle cam index mark lines up with the fast idle adjustment screw. Perform this adjustment while holding the choke valve closed.

FLOAT LEVEL AND DROP ADJUSTMENT



These adjustments are made in the same manner as on the Carter AFB. Refer to the procedures earlier in this section.

CHOKE UNLOADER ADJUSTMENT



  1. Hold the throttle wide open and the choke valve toward the closed position with a rubber band.
  2.  
  3. Bend the unloader tang on the throttle shaft lever to obtain a clearance of 0.170 in. (4.318mm) between the upper edge of the choke valve and the dividing wall of the air horn.
  4.  

CHOKE VACUUM BREAK ADJUSTMENT



  1. Hold the vacuum break in against its stop and the choke valve toward the closed position with a rubber band.
  2.  
  3. Bend the vacuum break link at an offset to obtain 0.120 in. (3.048mm) clearance between the upper edge of the choke valve and the air horn.
  4.  

CLOSING SHOE ADJUSTMENT



  1. Hold the primary and secondary throttle valves closed.
  2.  
  3. Bend the secondary closing shoe to obtain 0.020 (0.508mm) clearance between the positive closing shoes on the primary and secondary throttle levers.
  4.  

SECONDARY THROTTLE OPENING



  1. Check to see that the pickup lever contacts the loose lever on the primary shaft at both points simultaneously. Bend the pickup lever to obtain proper contact, if necessary.
  2.  
  3. If the primary and secondary throttle valve do not come to the wide open position simultaneously, bend the connecting link until they do.
  4.  

SECONDARY LOCKOUT ADJUSTMENT



  1. When the choke valve is closed, the lockout tang on the secondary throttle lever should engage the lockout dog. When the valve is open, the lockout dog should swing free of the tang.
  2.  
  3. Bend the lockout tang on the secondary throttle lever, if an adjustment is necessary.
  4.  

 
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