DETROIT DIESEL 53
Variable Speed Governor 14.4.5.
Use an accurate hand tachometer to determine the
maximum no-load speed of the engine, then make the
following adjustments, if required.
1. Refer to Fig. 7 and disconnect the booster spring
and the stop lever retracting spring.
2. Remove the two attaching bolts and withdraw the
variable speed spring housing and the variable speed
spring retainer located inside of the housing.
3. Refer to the following table and determine the stops
or shims required for the desired full-load speed. A split
stop can only be used with a solid stop (Fig. 4).
Stops
Full-Load Speed Solid
Split
Shims*
Fig. 5 - Adjusting Idle Speed
1. Place the stop lever in the RUN position and the
1200-2100
1
1
As Required
speed control lever in the IDLE position.
2100-2500
1
0
As Required
2500-2800
0
0
As Required
2. With the engine operating. loosen the lock nut and
*Maximum amount of shims .325"
turn the idle speed adjusting screw (Fig. 5 min or out
4. Install the variable speed spring housing and
until the engine idles at the recommended idle speed
recheck the maximum no-load speed.
The recommended idle speed is 550 rpm. hut may vary
with special engine applications.
5. If required. add shims to obtain the necessary
operating speed. For each .001" in shims added. the
3. Hold the idle speed adjusting screw and tighten the
operating speed will increase approximately 2 rpm.
lock nut.
IMPORTANT: If the maximum no-
Adjust Buffer Screw
load speed is raised or lowered more
With the engine idle speed properly set, adjust the
than 50 rpm by the installation or
buffer screw as follows:
removal of shims.
recheck the
1. With the engine running at idle speed. turn the
governor gap. If readjustment of the
buffer screw in (Fig. 6) so that it contacts the
governor gap is required.
the
position of the injector racks must be
rechecked.
NOTE: Governor stops are used to
limit the compression of the
governor spring, which determines
the maximum speed of the engine.
Adjust Idle Speed
After the maximum no-load speed has been set. adjust
the idle speed as follows:
Fig. 6 - Adjusting Buffer Screw
Fig. 4 - Location of Shims and Stops
1971 General Motors Corp.
May, 1971
SEC. 14.4.5 Page 3
