Detroit Diesel — Adjust the Governor Gap (Limiting Speed Mechanical Governor, 6, 8 and 12V-71)

Adjustments

From a Detroit Diesel service manual — check it applies to your exact model before use.

Procedure

1. Remove the two bolts and withdraw the governor high speed spring retainer cover.
2. Back out the buffer screw until it extends approximately 5/8 in from the lock nut.
3. Start engine, loosen idle speed adjusting screw lock nut, adjust idle screw to desired idle speed, tighten lock nut.
4. Stop engine; clean and remove governor cover and lever assembly; discard gasket.
5. Start and run engine between 800 and 1000 rpm by manual operation of the differential lever.
6. Check gap between low speed spring cap and high speed spring plunger with a .0015 in feeler gage.
7. If gap is incorrect, reset the gap adjusting screw.
8. Hold gap adjusting screw and tighten lock nut.
9. Recheck governor gap and readjust if necessary.
10. Stop engine and install governor cover and lever assembly using a new gasket.

Source: Detroit Diesel service 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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