Engine Tune-Up
3. Turn the speed adjusting screw (Fig. 5) until the
d e s i r e d speed i s o b t a i n e d . T u r n i n g t h e s c r e w
counterclockwise will decrease the speed setting.
Adjust Needle Valve
When starting the engine for the first time, eliminate
any air which may be trapped in the actuator oil
passages as follows:
1. Open the needle valve of the centrifugal governor
section (Fig. 6) until the engine hunts or surges. After
a half minute, gradually close the needle valve until
the engine speed just stabilizes. Closing the needle
valve farther than necessary will make the governor
slow to return to normal speed after a load change.
Never close the needle valve tight.
2. Test the action by manually disturbing the speed of
the engine. The engine should promptly return to its
original steady-state speed with only a small overshoot
or undershoot.
Speed Droop Adjustment
The governor is set with approximately 3% droop
when shipped from the factory. When the electric
governor section is controlling the engine, the speed
Fig. 5 - Adjusting Maximum No-Load Engine
Speed
Once set, these adjustments do not usually require
further adjustment.
I
Adjust Maximum No-load Speed
When shipped from the factory, the speed adjusting
screw is set for a speed approximately 4-1/2% above
rated speed at no-load (the usual factory droop setting
of 3% will reduce the speed to approximately 1-1/2%
above rated speed at full travel of the centrifugal
governor power piston). With the speed adjusting
screw at this setting during normal operation (i.e., with
t h e electric section controlling), the centrifugal
governor power piston will be held in its maximum
fuel position.
I f adjustment of the maximum no-load speed is
required, proceed as follows:
1. Disconnect the wiring at the receptacle on the
Fig. 6 - Location of Centrifugal Governor
governor cover.
Needle Valve
2. Start the engine and run it at no-load.
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