refacing the valves, check the
Caution. The cap and body mat
thickness from the top of the head to
must be an airtight seat, since it is a
the edge of the refaced outer surface.
point at which the energy cell is
This can be accomplished by
sealed into the head and any leakage
comparing the refaced valve with a
would cause burning of the
new one. If the refaced valve has 50
surrounding metal in a short time.
percent less margin, replace the
79.
Cylinder Head Assembly Reassembly and
valve.
Installation
(8)
After the valves have been refaced
a.
Reassembly.
Refer to figure 22 and
and the valve seats in the block
reassembly the cylinder head assembly in the reverse
refinished, the valve and seats should
order.
be ground (lapped). Place a small
amount of medium grade grinding
Caution: Make certain that the energy
compound around the face of the
cells have been torqued from 35 to
valve. Place a light spring under
40 ft-lbs to insure against possible
each valve and lap into place.
leaking
from
the
chamber at either the seat where the
Note. Avoid continuous round-and-
body contacts the head or the
round motions that would cut
contact surface between the cap and
grooves in the valve or seat. Rotate
the body.
only part of a turn with a suitable
tool, then raise it off the seat and
b.
Installation.
move it to a new position and the
(1)
Refer to figure 20 and install the
repeat the process.
cylinder head assembly on the
(9)
Test each valve for a tight seat by
engine.
making pencil marks across the face
(2)
Install the rocker arm assembly (par.
of the valve at short intervals, and
then rotate the valve against its seat
(3)
If water pump was removed, install
for part of a turn with firm pressure
the pump (par. 47).
and again lift out and observe if the
pencil marks are all rubbed out on the
(4)
Install the intake and exhaust
contact surface; if not, regrind until
manifold (TM 5-3820-205-20/2).
this test shows a gastight mating of
(5)
Install the water manifold (TM 5-3820-
valve to seat. It is imperative that the
205-20/2).
valves then be assembled in the
(6)
Install the fuel injector assembly (TM
same seats to which they were
ground.
(7)
Adjust the
valves
(TM
5-3820-
(10) Lap the energy cell body into the head
20520/2).
with valve grinding compound, using
the puller or a piece of wood of such
(8)
Install the valve covers (TM 5-3820-
size that it can be screwed into the
205-20/2).
threads on the energy cell, and lapped
(9)
Install the engine housing (TM 5-
in the same manner as you would a
3820-205-20/2).
valve in cylinder head.
(11) The contact surface where the cap
seats on the body must be lapped to
make an airtight seat.
Section XII. VIBRATION DAMPER AND DRIVE PULLEY
elasticity of the rubber. The purpose of the vibration
80.
General
damper is to reduce, or damper torsional vibrations
The vibration damper is mounted on the front of
caused by starting or changes in the load on the engine.
the engine drive pulley. It is a flywheel-type disk that is
The drive pulley, which is
made from two steel disks. One disk is mounted rigidly,
while the other is free to rotate, limited only by the
AGO 3456A
55