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General Motors GMG-857 — Electronic Governor Performance Adjustment

Adjustments

For the General Motors GMG-857, from the General Motors operator's manual.

Applies to: KEM GMG-857, General Motors 5.7L V8 (350 CID) engine

Before you start

  • To be performed by qualified personnel only.

Procedure

  1. Check GAIN and STABILITY controls, and external SPEED TRIM control, are set to mid-position.
  2. Crank the engine with D.C. battery power applied to the governor system.
  3. If engine is unstable after starting, turn GAIN and STABILITY counterclockwise until stable.
  4. Rotate the GAIN adjustment clockwise until instability develops, then counterclockwise until stability returns, then 1/8 turn counterclockwise.
  5. Rotate the STABILITY adjustment clockwise until instability develops, then counterclockwise until stability returns, then 1/8 turn counterclockwise.
  6. Adjust dead time compensation using posts E1, E2, E3 as required.

Specs & values

  • Controller factory set at approximately engine idle speed (1000 Hz Speed Sensor Signal)

Full service-parts list: KEM GMG-857 →

Source: General Motors operator's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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