Engine Tune-Up
SUPPLEMENTARY GOVERNING DEVICE ADJUSTMENT
ENGINE LOAD LIMIT DEVICE
Engines with mechanical governors may be equipped
Fig. 1. Make sure the counterbores in the adjusting
with a load limit device (Fig. 1) to reduce the
screw plates are up. The rocker arm shaft bracket bolts
maximum horsepower.
which fasten the adjusting screw plate to the brackets
are tightened to 75-85 lb-ft (102-115 Nm) torque (all
This device consists of a load limit screw threaded into
other rocker arm shaft bracket bolts are tightened to
a plate mounted between two adjacent rocker arm
90-100 lb ft or 122-136 Nm torque). Then adjust the
shaft brackets and a load limit lever clamped to the
load limit device, on each cylinder head, as follows:
injector control tube.
1. Loosen the load limit screw lock nut and remove the
The load limit device is located between the No. 1 and
screw.
No. 2 cylinders on each cylinder bank of a 6V engine,
between the No. 2 and No. 3 cylinders on each
2. Loosen the load limit lever clamp bolts so the lever
cylinder bank of an 8V engine, or between the No. 3
is free to turn on the injector rack control tube.
and No. 4 cylinders on each cylinder bank of a 12V
engine. On the 16V engine, four load limit devices are
3. With the screw out of the plate. adjust the load
used (one on each cylinder head). between the No. 2
screw lock nut so the bottom of the lock nut is 1
and No. 3 cylinder and between the No. 6 and No. 7
3/4" from the bottom of the load limit screw (Fig. 1)
cylinder on each bank.
for the initial setting.
When properly adjusted for the maximum horsepower
4. Thread the load limit screw into the adjusting screw
desired, this device limits the travel of the injector
plate until the lock nut bottoms against the top of the
control racks and thereby the fuel output of the
plate.
injectors.
5. Hold the injector rack control tube in the full-fuel
Adjustment
position and place the load limit lever against the
After the engine tune-up is completed, make sure the
bottom of the load limit screw. Then tighten the load
load limit devices are properly installed as shown in
limit lever clamp bolts.
6. Check to ensure that the injector racks will just go
into the full-fuel position -- readjust the load limit
lever if necessary.
7. Hold the load limit screw to keep it from turning,
then set the lock nut until the distance between the
bottom of the lock nut and the top of the adjusting
screw plate corresponds to the dimension (or number
of turns) stamped on the plate. Each full turn of the
s c r e w equals .042, or .007" for each flat on the
hexagon head.
NOTE: If the plate is not stamped, adjust the
load limit screw while operating the engine on a
dynamometer test stand and note the number
of turns required to obtain the desired
horsepower. Then stamp the plate accordingly.
8. Thread the load limit screw into the plate until the
lock nut bottoms against the top of the plate.
9. Hold the load limit screw to keep it from turning,
Fig. 1 - Engine Load Limit Device
then tighten the lock nut to secure the setting.
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