GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Rochester M2ME and E2ME 2-BBL Carburetors

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FLOAT ADJUSTMENT



See Figure 1

  1. Remove the air horn from the throttle body.
  2.  
  3. Using your fingers, hold the retainer in place and then push the float down into light contact with the needle.
  4.  
  5. Measure the distance from the toe of the float (furthest from the hinge) to the top of the carburetor (gasket removed).
  6.  
  7. To adjust, remove the float and gently bend the are to specifications. After adjustment, check the float alignment in the chamber. On engines equipped with the C-4 or the CCC system, where the float level varies more than 1 / 16 inch; from specifications, adjust the float as follows:
  8.  

Float too High:

Hold the retainer firmly in place and then push down the center of the float pontoon until the correct setting is obtained.

Float too Low:
  1. Lift out the meter rods and remove the solenoid connector screw.
  2.  
  3. Turn the lean mixture solenoid screw clockwise until the screw is bottomed lightly in the float bowl. Count and record the number of turns before the screw is bottomed.
  4.  
  5. Turn the screw counterclockwise and remove it. Lift the solenoid and the connector from the float bowl.
  6.  
  7. Remove the float and bend the arm up to adjust it. Put the float back in and check its alignment.
  8.  
  9. Upon installation make sure that the solenoid lean mixture screw is backed out of the float bowl EXACTLY the same number of turns as were recorded in Step 2.
  10.  



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Fig. Fig. 1: Adjusting the float-Rochester M2ME and E2ME

PUMP ADJUSTMENT



See Figure 2

All 1980 and later engines equipped with the C-4 or the CCC system have a non-adjustable pump lever. No adjustments are either necessary or possible.

  1. With the throttle closed and the fast idle screw off the steps of the fast idle cam, measure the distance from the air horn casting to the top of the pump stem.
  2.  
  3. To adjust the lever, support it firmly with a screwdriver and then bend it to obtain the proper specifications.
  4.  
  5. When the adjustment is correct, open and close the throttle a few times to check the linkage movement and alignment.
  6.  



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Fig. Fig. 2: Pump adjustment-Rochester M2ME and E2ME except for C-4 or CCC systems

CHOKE COIL LEVER ADJUSTMENT



See Figure 3

To complete this procedure you will need a start cover retainer kit; available at most auto parts suppliers.

  1. Drill out and remove the rivets. Retain the choke housing cover and then remove the thermostatic cover and coil assembly from the choke housing.
  2.  
  3. Place the fast idle cam follower on the high step of the fast idle cam.
  4.  
  5. Close the choke valve by pushing up on the thermostatic coil tang (counterclockwise).
  6.  
  7. Insert a drill or gauge of the specified size into the hole in the choke housing. The lower edge of the choke lever should be just touching the side of the gauge.
  8.  
  9. If the choke lever is not touching the side of the gauge, bend the choke rod until you see that it does.
  10.  



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Fig. Fig. 3: Adjusting the choke coil lever-Rochester M2ME and E2ME

FAST IDLE ADJUSTMENT



See Figure 4

  1. Set the ignition timing and curb idle speed. Disconnect and plug any hoses as directed on the emission control label.
  2.  
  3. Place the fast idle screw on the highest step of the fast idle cam.
  4.  
  5. Start the engine and adjust the engine speed to specifications with the fast idle screw.
  6.  



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Fig. Fig. 4: Preliminary setting of the fast idle with the carburetor assembly removed from the engine-Rochester M2ME and E2ME

FAST IDLE CAM (CHOKE ROD) ADJUSTMENT



See Figure 5

A special angle gauge should be used. If it is not available, an inch measurement may be substituted.

  1. Adjust the choke coil lever and the fast idle as previously detailed.
  2.  
  3. Rotate the degree scale until it is zeroed.
  4.  
  5. Close the choke valve completely and place the magnet on top of it.
  6.  
  7. Center the bubble.
  8.  
  9. Rotate the scale so that the specified degree is opposite the pointer.
  10.  
  11. Place the fast idle screw on the second step of the cam, against the rise of the high step.
  12.  
  13. Close the choke by pushing up on the choke coil lever or the vacuum break lever tang. You may hold it in position with a rubber band.
  14.  
  15. To adjust, bend the tang on the fast idle cam until the bubble is centered.
  16.  



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Fig. Fig. 5: Fast idle cam (choke rod) adjustment-Rochester M2ME and E2ME

FRONT VACUUM BREAK ADJUSTMENT



See Figure 6

  1. Follow Steps 1-5 of the Fast Idle Cam Adjustment procedure.
  2.  
  3. Set the choke vacuum diaphragm using an outside vacuum source.
  4.  
  5. Close the choke valve by pushing up on the choke coil lever or the vacuum break lever. You may hold it in position with a rubber band.
  6.  
  7. To adjust, turn the screw in or out until the bubble in the gauge is centered.
  8.  



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Fig. Fig. 6: Front vacuum break adjustment-Rochester M2ME and E2ME

REAR VACUUM BREAK ADJUSTMENT



See Figure 7

  1. Follow Steps 1-3 of the Front Vacuum Break Adjustment procedure.
  2.  
  3. To adjust, use a 1 / 8 in. Allen wrench to turn the screw in the rear cover until the bubble is centered. After adjusting, apply silicone sealant RTV over the screw head to seal the setting.
  4.  



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Fig. Fig. 7: Rear vacuum break adjustment-Rochester M2ME and E2ME

UNLOADER ADJUSTMENT



See Figure 8

  1. Follow Steps 1-5 of the Fast Idle Cam Adjustment procedure.
  2.  
  3. If they have been previously removed, install the choke thermostatic cover and the coil assembly into the choke housing.
  4.  
  5. Close the choke valve by pushing up on the tang on the vacuum break lever (you may hold it with a rubber band).
  6.  
  7. Hold the primary throttle valves wide open.
  8.  
  9. To adjust, bend the tang on the fast idle lever until the bubble on the gauge is centered.
  10.  



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Fig. Fig. 8: Unloader adjustment-Rochester M2ME and E2ME

 
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