Chevrolet Full Size Cars 1979-1989

Rochester M2ME and E2ME 2-bbl Carburetors

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FLOAT ADJUSTMENT





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Fig. Fig. 1 Adjusting the float M2ME and E2ME carburetors

  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.
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  5. Measure the distance from the toe of the float (furthest point from the hinge) to the top of the carburetor (gasket removed).
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  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 from specifications, adjust the float as follows:
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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.
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  5. Turn the screw counterclockwise and remove it. Lift the solenoid and the connector from the float bowl.
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  7. Remove the float and bend the arm up to adjust it. Put the float back in and check its alignment.
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  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.  

PUMP ADJUSTMENT



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.
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  3. To adjust the lever, support it firmly with a screwdriver and then bend it to obtain the proper specifications.
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  5. When the adjustment is correct, open and close the throttle a few times to check the linkage movement and alignment.
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CHOKE COIL LEVER ADJUSTMENT





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Fig. Fig. 2 Adjusting the choke coil lever M2ME and E2ME carburetors

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.
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  3. Place the fast idle cam follower on the high step of the fast idle cam.
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  5. Close the choke valve by pushing up on the thermostatic coil tang (counterclockwise).
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  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.
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  9. If the choke lever is not touching the side of the gauge, bend the choke rod until you see that it does.
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FAST IDLE ADJUSTMENT





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Fig. Fig. 3 The fast idle may be initially adjusted with the carburetor off the vehicle M2ME and E2ME carburetors

  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.
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  5. Start the engine and adjust the engine speed to specifications with the fast idle screw.
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FAST IDLE CAM (CHOKE ROD) ADJUSTMENT



If possible, a special angle gauge should be used for this adjustment. If it is not available, an inch measurement can be substituted.

  1. Adjust the choke coil lever and the fast idle as previously detailed.
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  3. Rotate the degree scale until it is zeroed.
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  5. Close the choke valve completely and place the magnet on top of it.
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  7. Center the bubble.
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  9. Rotate the scale so that the specified degree is opposite the pointer.
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  11. Place the fast idle screw on the second step of the cam, against the rise of the high step.
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  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.
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  15. To adjust, bend the tang on the fast idle cam until the bubble is centered.
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FRONT VACUUM BREAK ADJUSTMENT



  1. Follow Steps 1-5 of the Fast Idle Cam (Choke Rod) Adjustment procedure.
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  3. Set the choke vacuum diaphragm using an outside vacuum source.
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  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.
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  7. To adjust, turn the screw in or out until the bubble in the gauge is centered.
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REAR VACUUM BREAK ADJUSTMENT





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Fig. Fig. 4 Rear vacuum break adjustment M2ME and E2ME carburetors

  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.  

UNLOADER ADJUSTMENT





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Fig. Fig. 5 Unloader adjustment M2ME and E2ME carburetors

  1. Follow Steps 1-5 of the Fast Idle Cam (Choke Rod) 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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