TM 9-4940-549-14&P
0.3725 to 0.3735 inch.
Stem diameter of exhaust valves shall be
0.3740 to 0.3750 inch.
(16) Check all threads for crossing, stripping, and peening. Repair
minor thread damage with a thread chaser.
(17) Repair slightly damaged valves as follows:
(a) Polish stems with crocus cloth to remove minor nicks and
scratches.
(b) Reface slightly pitted valves on a valve grinding machine.
See table 1-1 for valve seat width.
(18) If valves and valve seats have been refinished or if contact
surfaces are only slightly pitted, lap each valve into its seat as
follows:
Install a light coil spring with enough tension to hold
(a)
valve off its seat.
Lubricate valve stem and guide.
(b)
Apply a thin coating of coarse grinding compound to the
(c)
valve face.
Insert valve into valve guide and attach a hand grinding
(d)
tool .
Avoid continuous round and round motion
which could cut grooves in valve face
and seat.
(e)
Rotate valve back and forth while applying firm pressure
on the grinding tool.
Release pressure on grinding tool, allowing coil spring to
(f)
lift valve from its seat.
Rotate valve 15 to 20 and repeat the grinding process.
(g)
Periodically clean valve and seat to check progress.
(h)
(i)
Replenish grinding compound and continue grinding until
the valve seat and valve surfaces are in contact.
Remove valve. Clean valve and valve seat to remove all
(j)
traces of coarse grinding compound.
Apply a thin coating of fine grinding compound to face of
(k)
valve.
12-15
