Engine Tune-Up
DETROIT DIESEL
is 500 rpm. However, the idle speed may vary with
11. Position the remaining injector rack control levers
as outlined in Steps 9 and 10.
special engine applications.
3. Hold the idle speed adjusting screw and tighten the
lock nut.
Adjust Maximum No-load Speed
1. With the engine running, move the speed control
lever to the maximum speed position. Use an accurate
Adjust Buffer Screw
tachometer to determine the no-load speed of the
engine.
1. With the engine running at idle speed, turn the
buffer screw in (Fig. 7) so that it contacts the stop
NOTE: Do not overspeed the engine.
lever as lightly as possible and still eliminates engine
roll.
2. Loosen the lock nut and adjust the maximum speed
adjusting screw (Fig. 5) until the required no-load
NOTE Do not raise the engine idle speed more
speed is obtained.
than 20 rpm with the buffer screw. Check the
maximum no-load speed to make sure it has not
3. Hold the adjusting screw and tighten the lock nut.
increased over 25 rpm by the buffer screw
setting.
Adjust Engine Idle Speed
Adjust Governor Booster Spring
1. Make sure the stop lever is in the run position and
place the speed control lever in the idle position.
The governor booster spring is used on some engines
to reduce the force necessary to move the speed
2. With the engine running at normal operating
control lever from the idle speed position to the
temperature, loosen the lock nut and turn the idle
maximum speed position. Adjust the booster spring as
speed adjusting screw (Fig. 6) until the engine idles at
follows:
the recommended speed. The recommended idle speed
1. Move the speed control lever to the idle speed
position.
2. Reduce the tension on the booster spring, if not
Fig. 5 - Adjusting Maximum No-Load Engine
Fig. 6 - Adjusting Idle Speed
Speed
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