Engine Tune-Up
5. Start and run the engine between 800 and 1000 rpm
by manual operation of the differential lever.
CAUTION: Do not overspeed the engine.
6. Check the gap between the low speed spring cap
and the high-speed spring plunger (Fig. 3) with a
.0015" feeler gage. If the gap setting is incorrect, reset
the gap adjusting screw. If the setting is correct, the
.0015" movement can be seen by placing a few drops
of oil into the governor gap and pressing a screw
driver against the gap adjusting screw. Movement of
the cap toward the plunger will force the oil from the
gap in the form of a small bead.
7. Hold the gap adjusting screw and tighten the lock
nut.
8. Recheck the gap and readjust, if necessary.
9. Stop the engine and, using a new gasket, install the
governor cover and lever assembly.
Position Injector Rack Control levers
Fig. 4 - Positioning No. 4L Injector Rack
Control Lever (Two Screw Assembly)
The position of the injector racks must be correctly, set
in relation to the governor. Their position determines
1. Adjust the idle speed adjusting screw until 1/2" of
the amount of fuel injected into each cylinder and
the threads (12-14 threads) project from the lock nut
ensures equal distribution of the load.
when the nut is against the high-speed spring plunger.
Certain engines use spring loaded injector control
CAUTION: A false fuel rack setting may result
tube assemblies which have a yield spring at each
if the idle speed adjusting screw is not backed
injector rack control lever and only one screw and lock
out as noted above.
nut to keep each injector rack properly positioned
Adjust the single screw and loch nut on each injector
rack control lever the same as for the two screw rack
NOTE: This adjustment lowers the tension on
control lever (refer to Fig. 3 for 6, 8 and 12V 71
the low-speed spring so it can be easily
compressed. This permits closing the low speed
engine governor) Properly positioned injector rack
control levers with the engine at full load will result in
gap without bending the fuel rods or causing
the following:
the yield mechanism spring, to yield or stretch.
1. Speed control lever at the maximum speed position.
2. Back out the buffer screw approximately 5/8", if it
has not already been done.
2. Governor low speed gap closed.
3. Loosen all of the inner and outer injector rack
3. High speed spring plunger on the seat in the
control lever adjusting screws on both cylinder banks.
governor control housing.
Be sure all of the levers are free on the injector control
tubes.
4. Injector fuel control racks in the full fuel positron.
4. Check for any bind in the governor control tube
The letters R and L indicate the injector location in
linkage by moving the linkage through its full range
the right or left cylinder bank, viewed from the rear of
of travel.
the engine. Cylinders are numbered starting at the
front of the engine on each cylinder bank. Adjust the
5. Remove the clevis pins which attach the right rear
No. 4R Injector rack control lever first to establish a
guide for adjusting the remaining right bank injector
back and both left bank fuel rods to the injector
control tube levers.
rack control levers.
Page 100
