Chevrolet Full-size Cars 1968-1978 Repair Guide

Rochester M4ME and E4ME 4-Bbl. Carburetors

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Fig. Fig. 1 Exploded view of a 1976-78 Rochester four barrel carburetor



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Fig. Fig. 2 Component list for the 1976-78 Rochester four barrel carburetor

Float, pump, choke coil lever, fast idle, fast idle cam (choke rod), front and rear vacuum break and unloader adjustments on these two carburetors are identical to those detailed in the M2ME information. Please refer to them. There are, however, a number of procedures that apply only to the 4-bbl carburetors and to specific years. Please refer to the appropriate illustration.

ADJUSTMENTS



Air Valve Rod


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Fig. Fig. 3 Adjusting the air valve rod on the Rochester M4ME and E4ME carburetors

  1. Using an outside vacuum source, seat the choke vacuum diaphragm. Put a piece of tape over the purge bleed hole if so equipped.
  2.  
  3. Close the air valve completely.
  4.  
  5. Insert the gauge between the rod and the end of the slot in the lever.
  6.  
  7. Bend the rod to adjust the clearance.
  8.  

Secondary Lockout


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Fig. Fig. 4 Secondary lockout adjustment on the Rochester M4ME and E4ME carburetors

  1. Pull the choke wide open by pushing out on the choke lever.
  2.  
  3. Open the throttle until the end of the secondary actuating lever is opposite the toe of the lockout lever.
  4.  
  5. Measure the clearance between the lockout lever and the secondary lever.
  6.  
  7. Bend the lockout pin until the clearance is in accordance with the proper specifications.
  8.  

Secondary Closing


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Fig. Fig. 5 Secondary closing adjustment on the Rochester M4ME and E4ME carburetors

  1. Make sure that the idle speed is set to the proper specifications.
  2.  
  3. The choke valve should be wide open with the cam follower off of the steps of the fast idle cam.
  4.  
  5. There should be 0.020" clearance between the secondary throttle actuating rod and the front of the slot on the secondary throttle lever with the closing tang on the throttle lever resting against the actuating lever.
  6.  
  7. To adjust, bend the secondary closing tang on the primary throttle actuating rod.
  8.  

Secondary Opening


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Fig. Fig. 6 Secondary opening adjustment on the Rochester M4ME and E4ME carburetors

  1. Open the primary throttle valves until the actuating link contacts the upper tang on the secondary lever.
  2.  
  3. With the two point linkage, the bottom of the link should be in the center of the secondary lever slot.
  4.  
  5. With the three point linkage, there should be 0.070" clearance between the link and the middle tang.
  6.  
  7. To adjust, bend the upper tang on the secondary level.
  8.  

Air Valve Spring


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Fig. Fig. 7 Adjusting the air valve spring on the Rochester M4ME and E4ME carburetors

To adjust the air valve spring windup, loosen the Allen lockscrew and then turn the adjusting screw counterclockwise so as to remove all spring tension. With the air valve closed, turn the adjusting screw clockwise the specified number of turns after the torsion spring contacts the pin on the shaft. Hold the adjusting screw in this position and tighten the lockscrew.

 
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