i. Illustration. Before installing an injector in an
engine, remove carbon deposits from the beveled
seat of injector tube in cylinder head. This will
assure correct alignment of injector and prevent
any undue stress from being exerted against spray
tip. Use injector tube bevel reamer to clean carbon
just pass over the top of the injector follower.
from injector tube. Exercise care to remove only
(6) Hold the push rod and tighten the lock
carbon so that proper clearance between injector
nut. Check the adjustment and readjust, if
body and cylinder head be maintained. Pack the
flutes of reamer with grease to retain the carbon
(7) Time the remaining injectors as outlined
removed from the tube. Install fuel injector as
3-15. Rocker Arms and Push Rods
(1) Refer to figure 3-20 and install the fuel
a. General. Three rocker arms are provided for
injector and fuel line. Insert the injector into the
each cylinder; the two outer arms operate the
injector tube with the dowel in the injector body
exhaust valves and the center arm operates the fuel
registering with the locating hole in the cylinder
injector. The rocker arms are operated by the
camshaft through cam followers and short push
rods extending through the cylinder head.
Check the injector control rack for free movement.
Excess torque can cause the control rack to stick or
(1) Remove the rocker arm cover (TM 10-
(2) Refer to figure 3-33 and remove rocker
(2) Move rocker arm assembly into position
arms and push rod.
and tighten the rocker arm bracket bolts to 50 to 55
c. Disassembly. R e f e r t o figure
foot pounds torque.
disassemble the rocker arm and push rod assembly
in numerical sequence.
There is a possibility of damaging
exhaust valves if the exhaust valve
(1) Inspect the rounded end of push rod for
bridges are not resting on the ends of
exhaust valves when tightening the
(2) Inspect the springs for cracks and breaks.
rocker shaft bracket bolts. Note position
( 3 ) Inspect the cam f o l l o w e r holes in the
of exhaust valve bridges before, during
cylinder head to ensure they are clean, smooth, and
and after tightening the rocker shaft
free of score marks. Dress out any score marks with
(4) Inspect the cam follower roller for freedom
D O not bend the fuel pipes and do not
of movement on its pin, flat spots and scuff marks.
(5) Inspect cam follower and cam follower
guides (fig. 3-35) (cylinder head removed).
o f f u e l l i n e s a n d r e s u l t i n leaks.
(6) Check the cam follower-to-cylinder head
Lubrication oil diluted by fuel oil can
clearance. The clearance must not exceed 0.006
cause serious damage to the engine
inch with new parts.
(7) Check the total side clearance between the
j. Fuel Injector Timing.
roller and follower; this clearance must not be less
(1) Place the speed control lever in the idle
than 0.015 inch or more than 0.023 inch.
speed position. If a stop lever is provided, secure it
(8) Check the clearance between the roller
in the no-fuel position.
bushing and pin (fig. 3-36). If the diameter
(2) Rotate the crankshaft, manually or with
clearance exceeds 0.010 inch, replace the cam
starting motor, until the exhaust valves are fully
follower assembly or install a new cam roller and
depressed on the cylinder to be timed.
e. Reassembly. Refer to figure 3-34 and
If a wrench is used on the crankshaft
reassemble the rocker arm, and push rod assembly.
bolt at the front of the engine, do not
Assembly is the reverse procedure of disassembly.
t u r n the crankshaft in a left-hand
f. Installation. Refer to figure 3-33 and install the
direction of rotation or the bolt will
rocker arm and push rods. Refer to TM 10-3930-
243-12 and adjust the push rods and rocker arms.
(3) Place the small end of injector timing gage