DETROIT DIESEL
Engine Tune-Up
b. Remove the high-speed spring from the high-
9. Position the remaining injector rack control levers
speed spring plunger and add or remove shims
as outlined in Steps 6 and 7.
(Fig. 6) as required to establish the desired
engine no-load speed.
10. Connect the fuel rod to the injector control tube
lever.
NOTE: For each .010" shim added, the engine
11. Turn the idle speed adjusting screw in until it
speed will be increased approximately 10 rpm.
projects 3/16" from the lock nut to permit starting the
engine. Tighten the lock nut.
c. Install the high-speed spring on the plunger and
install the spring assembly in the governor
12. Use a new gasket and replace the valve rocker
h o u s i n g . Install the spring retainer in the
cover.
governor housing and tighten it securely.
d. Start the engine and recheck the engine no-load
speed. Repeat the procedure as necessary to
Adjust Maximum No-load Engine Speed
establish the no-load speed.
All governors are properly adjusted before leaving the
factory. However, if the governor has been recondi-
tioned or replaced, and to ensure the engine speed will
Adjust Idle Speed
not exceed the recommended no-load speed as given
on the engine option plate, set the maximum no-load
With the maximum no-load speed properly adjusted,
speed as follows:
adjust the idle speed as follows:
TYPE A GOVERNOR SPRINGS (Fig. 6):
1. With the engine running at normal operating
temperature and with the buffer screw backed out to
1. Loosen the lock nut (Fig. 5) and back off the high-
avoid contact with the differential lever, turn the idle
speed spring retainer approximately five turns.
speed adjusting screw (Fig. 7) until the engine is
o p e r a t i n g at approximately 15 rpm below the
2. With the engine at operating temperature and no-
recommended idle speed.
load on the engine, place the speed control lever in the
full-fuel position. Turn the high-speed spring retainer
NOTE: The recommended idle speed for non-
IN until the engine is operating at the recommended
EPA certified engines is 500-600 rpm, but may
no-load speed.
vary with special engine applications.
The best method of determining the engine speed is
2. Hold the idle speed adjusting screw and tighten the
with an accurate tachometer.
lock nut.
3. Hold the high-speed spring retainer and tighten the
lock nut.
TYPE B GOVERNOR SPRINGS (Fig. 6):
1. Start the engine and after it reaches normal
operating temperature, remove the load from the
engine.
2. Place the speed control lever in the maximum speed
position and note the engine speed.
3. Stop the engine and, if necessary, adjust the no-load
speed as follows:
a. Remove the high-speed spring retainer, high-
speed spring and plunger.
CAUTION: To prevent the low-speed spring and
sap from dropping into the governor, be careful
not to jar the assembly while it is `being
Fig. 7 - Adjusting Engine Idle Speed
removed.
Page 82
