Chevrolet Full-size Cars 1968-1978 Repair Guide

Rochester 2GC, 2GV 2-Bbl. Carburetors

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Fig. Fig. 1 Rochester 2GC, 2GV Specifications



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Fig. Fig. 2 Rochester 2GC, 2GV Specifications



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Fig. Fig. 3 Exploded view of the 1976-78 Rochester 2GC carburetor-Rochester 2GV similar



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Fig. Fig. 4 Component list for the 1976-78 Rochester 2GC carburetor

These procedures are for both the 1 1 / 4 and 1 1 / 2 models; where there are differences these are noted. The 1 1 / 2 model has larger throttle bores and an additional fuel feed circuit to make it suitable for use on the 350 V8s.

ADJUSTMENTS



Fast Idle

On 2GC and 2GV models the fast idle is set automatically when the curb idle and mixture is set.

Fast Idle Cam


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Fig. Fig. 5 Adjusting the fast idle cam on the Rochester 2GV carburetor

  1. Turn the idle screw onto the second step of the fast idle cam, abutting against the top step.
  2.  
  3. Hold the choke valve toward the closed position and check the clearance between the upper edge of the valve and the air horn wall.
  4.  
  5. If this measurement varies from specifications, bend the tang on the choke lever.
  6.  

Choke Unloader
  1. Hold the throttle valves wide open and use a rubber band to hold the choke valve toward the closed position.
  2.  
  3. Measure the distance between the upper edge of the choke valve and the air horn wall.
  4.  
  5. If this measurement is not within specifications, bend the unloader tang on the throttle lever to correct it.
  6.  

Accelerator Pump Rod


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Fig. Fig. 6 Adjusting the accelerator pump rod on the Rochester 2GV carburetor

  1. Back out the idle stop screw and close the throttle valves in their bores.
  2.  
  3. Measure the distance from the top of the air horn to the top of the pump rod.
  4.  
  5. Bend the pump rod at angle to correct this dimension.
  6.  

Float Level


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Fig. Fig. 7 Adjusting the float level on the Rochester 2GV carburetor

Invert the air horn and, with the gasket in place and the needle seated, measure the level as follows:

On nitrophyl floats, measure the air horn gasket to the lip on the toe of the float.

On brass floats, measure the air horn gasket to the lower edge of the float seam.

Bend the float tang to adjust the level.

Float Drop


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Fig. Fig. 8 Adjusting the float drop on the Rochester 2GV carburetor

Holding the air horn right side up, measure float drop as follows:

On nitrophyl floats, measure from the air horn gasket to the lip at the toe of the float.

On brass floats, measure from the air horn gasket to the bottom of the float.

Bend the float tang to adjust either type of float.

 
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