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TM 10-3930-671-24
2.
All intake and exhaust valves have umbrella
seals. Soak in boiling water for several minutes
prior to installation.
3.
Reassemble the valves and springs in the head
with the seal, retainer, and retainer lock.
Installing Umbrella Seals
ROCKER ARMS
1.
Inspect the rocker arm shaft for wear. If the
shaft has "shoulders" on it due to wear, replace.
Blow out oil holes with air.
2.
Examine rocker arms for cracks, condition of
valve contact surface and worn bores. Replace
all defective rocker arms or any having over
.005" (0.13mm) clearance between shaft and
arm.
3.
Inspect the rocker arm brackets for cracks or
other damage.
VALVE PUSH RODS
1.
Inspect push rods for bends or twist and
examine the ball and cup ends for excessive
wear.
Replace
rods
that
are
faulty
or
excessively worn.
2.
To prevent damage to push rods, replace after
the cylinder head is installed.
Push Rod Inspection for Runout
CHECKING BORE WEAR
1.
Clean the ring of carbon from around the top of
the cylinder bore formed above the travel of the
top ring.
2.
Determine the original diameter of the cylinder
barrel by checking this unworn area with an
inside micrometer or a dial bore gauge at
intervals of approximately 45°.
Measuring Original Bore Diameter Above Ring Travel
3.
Check in same manner the top of the ring travel
area approximately 1/4" (6mm) below the
shoulder.
4.
The maximum difference in the above checks,
indicates the amount of cylinder bore wear. If
less than .008" (0.20mm), re-ringing will be
suitable and if over .008" (0.20mm) re-boring is
recommended.
PREPARING CYLINDER WALLS FOR RE-RINGING
OR RE-BORING
1.
Ridge ream the cylinders to remove the unworn
area at the top so that the new rings when
assembled will not bump and distort both
themselves and the piston lands.
Ridge Reaming Top of Cylinder
F-173
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