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Home >> GMC >> 1980 >> Forward Control 5.7L Eng VIN M, Automatic Trans, Trans Mfr CD 475/M40 >> Repair and Diagnosis >> Engine Performance >> Fuel Delivery >> ROCHESTER M4MC 4-Barrel >> Adjustments >> Choke Unloader

Choke Unloader

NOTE: This adjustment is performed using the choke valve angle gauge. See procedure at beginning of Adjustments.
  1. Adjust automatic choke as previously outlined. Hold throttle valves wide open. See  Fig 1 . 
  2. If engine is warm, close choke valve by pushing up on vacuum break lever tang. Hold in position with a rubber band.
  3. Bubble on choke valve angle gauge should be centered with specified degree mark opposite pointer.
  4. To adjust, bend choke unloader tang on throttle lever until bubble of choke valve angle gauge is centered.
    Fig 1: Adjusting Choke Unloader
    G09348201Courtesy of GENERAL MOTORS COMPANY