Engine Tune-Up
POWER CONTROL DEVICE
engine, between the No. 2 and No. 3 cylinders on
each cylinder bank of an 8V engine, or between the
No. 3 and No. 4 cylinders on each cylinder bank of a
12V engine.
Adjustment
After the engine tune-up is completed, adjust the
p o w e r control device on both cylinder banks as
follows:
1. Place the vehicle on a chassis dynamometer and
check the maximum wheel horsepower.
2. Loosen the power control spring attaching bolts.
Then adjust both springs until they project parallel to
the cylinder heads when the injector control racks are
held in the full-fuel position. Tighten the spring
a t t a c h i n g bolts to 7-9 lb-ft (10-12 Nm) torque to
retain the adjustment.
3. Set each power control device, while holding the
injector control racks in the full-fuel position, by
turning the adjusting screw down (clockwise) until it
just touches the spring and the lock nut is tight against
Fig. 2 - Power Control Device
the plate. Then release the injector control racks.
The power control (torque limiting) device (Fig. 2) is
NOTE: Wipe the oil from each spring and the
used to limit the maximum horsepower output at the
bottom of each adjusting screw so the point of
wheels without diminishing the performance at lower
contact can be seen readily.
speeds where full power may be required. It limits the
horsepower at, or just below, the normal full load
CAUTION: Steps 2 and 3 must be completed on
governed speed. These limiting characteristics are
both cylinder banks before proceeding with
p r o p o r t i o n a t e l y lessened as the engine speed is
Step 4.
reduced and the horsepower required is reduced.
4. Start the engine. Then. with the engine running at
f u l l governed speed, c h e c k the horsepower. If
This device, one on each cylinder bank. consists of an
necessary. re-adjust the screws to obtain the specified
adjusting screw threaded into a plate mounted between
horsepower. Turn the screws down to decrease the
two adjacent rocker arm shaft brackets and a spring
horsepower: t u r n the screws up to increase the
attached to a clamp on the injector control tube.
horsepower. When the desired wheel horsepower is
obtained. hold the screws from turning and tighten the
NOTE: The rocker arm shaft bracket bolts that
lack nuts.
retain the adjusting screw plates are, tightened
to 75-85 lb-ft ( 102 - 115 Nm) torque; all other
NOTE: If a dynamometer is not available, back
rocker arm shaft bracket bolts are tightened to
up the lock nuts the distance stamped on the
90-100 lb-ft (122-136 Nm) torque.
plates. Then turn the screws and lock nuts down
together until the lock nuts bottom on the plates.
Hold the screws from turning and tighten the
The power control device is located between the No. 1
lock nuts.
and No. 2 cylinders on each cylinder bank of a 6V
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