Rocker Arms and Push Rods - TM-10-3930-243-340084

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

necessary.

flutes of reamer with grease to retain the carbon

(7) Time the remaining injectors as outlined

removed from the tube. Install fuel injector as

above.

follows:

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

head.

camshaft through cam followers and short push

rods extending through the cylinder head.

NOTE

Check the injector control rack for free movement.

b. Removal.

Excess torque can cause the control rack to stick or

(1) Remove the rocker arm cover (TM 10-

bind.

3930-243-12).

(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

3-34 and

foot pounds torque.

disassemble the rocker arm and push rod assembly

CAUTION

in numerical sequence.

There is a possibility of damaging

d. Inspection.

exhaust valves if the exhaust valve

(1) Inspect the rounded end of push rod for

bridges are not resting on the ends of

wear.

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

bolts.

crocus cloth.

CAUTION

(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.

exceed

specified torque.

Excessive

(5) Inspect cam follower and cam follower

torque will twist or fracture flared end

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.

bearings.

(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.

pin.

CAUTION

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-

loosen.

243-12 and adjust the push rods and rocker arms.

(3) Place the small end of injector timing gage

3-46