DETROIT DIESEL
Engine Tune-Up
3. Install the high-speed spring cover and tighten the
two bolts.
Adjust Buffer Screw
With the idle speed properly set, adjust the buffer
screw as follows:
1. With the engine running at normal operating
temperature, turn the buffer screw in (Fig. 8) so it
contacts the differential lever as lightly as possible and
still eliminates engine roll.
NOTE: Do not increase the engine idle speed
more than 15 rpm with the buffer screw.
2. Recheck the maximum no-load speed. If it has
increased more than 25 rpm, back off the buffer screw
Fig. 8 - Adjusting Buffer Screw
until the increase is less than 25 rpm.
3. Hold the buffer screw and tighten the lock nut.
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