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 TM 55-1905-217-34
the cylinder head with Trichloroethylene or other good solvent. Also, wash the valve inserts with the same solvent. Dry
both the counterbores and the inserts with compressed air.
(c) Inspect the valve seat insert counterbores in the cylinder head for cleanliness, concentricity, flatness and
cracks. The counterbores in the cylinder heads have a diameter of 1.626 inch to 1.627 inch and a depth of .3705 inch to
.3845 inch. If required, use valve seat inserts which are .010 inch oversize on the outside diameter.
(d) Immerse the cylinder head for at least 30 minutes in water heated to a temperature of 185F. to 200F.
(e) Rest the cylinder head, bottom side up on a work bench and locate the insert squarely in the counterbore,
seating face up. Install the insert in the cylinder head while the head is still hot and the insert is at room temperature,
otherwise installation will be difficult and the parts may be damaged.
(f) Drive the inserts in place with installer J 1736, until they seat solidly in the cylinder head.
(g) Grind the valve seat inserts and check them for concentricity in relation to the valve guides as outlined below.
(3) Exhaust Valves and Springs. After the valve guides have been checked or replaced, the valves and valves seat
inserts replaced or reconditioned, install the exhaust valves as follows:
(a) Clean the valve guides.
(b) Lubricate the valve stems and slide the valves all the way into the guides.
NOTE
If reconditioned valves are used, install them in the same relative location from which they
were removed.
(c) Hold the valves in place with a strip of masking tape and turn the cylinder head right side up on the work
bench. Place a board under the head to support the valves and to provide clearance between the cam followers and the
bench.
(d) Install the valve spring seats.
(e) Install the valve springs, and valve spring caps.
(f) Thread the valve spring compressor J 7455 into one of the rocker shaft bolt holes in the cylinder head.
(g) Apply pressure to the free end of the tool to compress the valve spring and install the two piece tapered valve
lock. Exercise care to avoid scoring the valve stem with the valve cap when compressing the spring.
CAUTION
Compress the valve spring only enough to permit installation of the valve locks.
Compressing the spring too far may result in damage to the valve guide oil seal if
used.
(h) Release the tool and install the valve locks on the remaining exhaust valves in the same manner.
NOTE
After the valves have been installed, make sure that none of the valve heads protrude more
than the limits shown in figure 3-56 above the surface of the cylinder head when the valves
are fully closed.
3-16. Idler Gear Assembly and Hole Spacer
a. General.
(1) The idler gear (fig. 3-58) mounts on a double row, tapered roller bearing which, in turn, is supported on a
stationary hub. A hollow pin serves a two-fold purpose; first, as a locating dowel it prevents the idler gear hub from
rotating and, second, the hollow pin conducts oil under pressure from an oil gallery in the cylinder block through a passage
in the gear hub to the roller bearing inner races.
3-77
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