P-9-TM-457-35
T.O. 35C2-3-442-2
TM-07464A-35
TM 5-6115-457-34
seat inserts (31 and 33) must be replaced.
manufacturer's minimum and maximum
Use a suitable valve seat extractor to
dimension, it can not be reground and must
replace valve seat inserts.
be replaced. Refer to figure 8-55.
d. To install new valve seat inserts
i. Inspect valves (30 and 32) using a
that have been worn beyond acceptable
suitable micrometer, and check valve head
grinding tolerances, observe the following:
diameter, valve face angle, closed valve
(This does not include valve seat inserts
projection, valve head diameter, and valve
that are loose.)
lip thickness. Refer to figure 8-55. If
limits are exceeded, replace valve.
1. Clean cylinder head with an
approved cleaning solvent, and dry
j. Inspect rotocoil assembly (27) for
thoroughly.
freedom of rotation. Place rotocoil assem-
bly in suitable test fixture with a 1 inch hole.
2. Refer to table 1-1 to ensure that
Insert the rotocoil in the hole and load the
head counterbores meet allowable limits
top of the rotocoil to 58 pounds. The de-
before installing inserts.
flected height of the rotocoil under this load
should be 0.295 0. 010 inch when meas-
3. Immerse the cylinder head in
ured from the fixture surface to the top of
water heated to 180F to 200F for at least
the rotocoil. If this deflection required is
30 minutes.
not met, replace rotocoil assembly.
4. Rest the cylinder head upside
k. Discard all gaskets.
down on a bench, and lay a new insert in
counterbore, valve seat up. This must
8-193. REPAIR.
be done quickly while the cylinder head is
hot and the insert is cold (room
a. When results of inspections in step g. ,
temperature).
not properly seated, grind the valve seat
5. Using an approved valve seat
or seats using an approved valve seat
insert installation tool, drive insert down
grinder, and grind the valve or valves,
tight into counterbore.
using a suitable valve face grinding
machine.
6. Grind the new valve seat insert
to the minimum allowable limit of the valve
b. After valve seats and/or valve faces
seat insert tolerances shown in table 1-1.
have been ground until they are smooth and
concentric with valve guides, clean all
e. To replace a loose valve seat insert,
parts with an approved cleaning solvent,
the insert counterbore must be enlarged to
and dry thoroughly.
accept the next standard oversize insert.
After enlarging counterbore, refer to
c. If exhaust and intake valve faces
preceding step d. for insert installation
(30 and 32, figure 8-54) and valve seat
procedure.
inserts (31 and 33) have been ground for
proper seating, the dimensional specifica-
8-194. REASSEMBLY.
tions outlined in figure 8-55 must be met.
Refer to figure 8-54 and reassem-
If dimensions are unacceptable, exhaust
ble cylinder head group in the reverse
and intake valves (30 and 32) and valve
Change 1
8-115
