DETROIT DIESEL
Engine Tune-Up
Fig. 4 Adjusting Droop Bracket
injector control tube. Then alternately tighten both the
inner and outer rack control lever adjusting screws.
Fig. 3 Adjusting Length of Fuel Rod
9. Recheck the rear injector fuel rack to be sure that it
joint or end bearing and the terminal lever clamping bolt
has remained snug on the ball end of the rack control
securely.
lever while adjusting the adjacent injector. If the rack of
the rear injector has become loose, back off slightly on
NOTE: It will be necessary to slide the
the inner adjusting screw on the adjacent injector rack
terminal lever partially off of the shaft to
control lever. Tighten the outer adjusting screw.
attach the fuel rod end bearing or ball joint
When the settings are correct, the racks of both injectors
to the terminal lever.
must be snug on the ball end of their respective rack
control levers.
6. Hold the terminal lever in the full-fuel position and
loosen the inner adjusting screw 1/8 of a turn and
10. Position the remaining rack control levers as
tighten the outer adjusting screw 1/8 of a turn to retain
outlined in Steps 8 and 9.
the adjustment. This is done to prevent the governor
from bottoming the injector racks, since there is no load
11. Insert the clevis pin between the fuel rod and the
limit screw on this governor.
injector control tube lever.
7. Remove the clevis pin between the fuel rod and the
12. Install the terminal lever return spring.
injector control tube lever.
Adjust Speed Droop
NOTE: Cover the cylinder head oil drain
back hole, located under the control
The purpose of adjusting the speed droop is to establish
lever, when removing the fuel rod clevis
a definite engine speed at no load with a given speed at
pin to prevent its loss and possible
rated full load.
damage to the engine.
The governor droop is set at the factory and further
8. Manually hold the rear injector in the full-fuel
adjustment should be unnecessary. However, if the
position and turn down the inner rack control lever
governor has had major repairs, the speed droop should
adjusting screw of the adjacent injector until the injector
be readjusted.
rack of the adjacent injector has moved into the full-fuel
position and the inner adjusting screw is bottomed on
The best method of determining the engine speed is
the injector control tube. Turn the outer adjusting screw
with an accurate hand tachometer.
down until it bottoms lightly on the
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