Inspect the bearing seating surfaces
(6)
Measure the new rings for proper side
and mating surfaces for nicks, burrs,
clearance with the piston. Replace
and scratches. Replace all damaged
the piston if the groove clearance
or defective parts.
exceeds 0.008 inch.
99.
Piston and Connecting Rod
Assemblies
(7)
Install the piston rings in the
Reassembly and Installation
respective cylinder sleeve and check
for proper ring gap with a feeler gage.
Reassembly.
Refer to figure 30 and
a.
The proper ring gap is from 0.018 to
reassemble the piston and connecting rod assemblies in
0.032 inch. If the ring gap is smaller
the reverse order.
than that specified, dress off the ends
Note. Install the sleeve (17) in the
of the rings squarely with a file.
engine block by using a block of
(8)
Measure the piston pins with an
wood and hammer to drive the sleeve
outside
for
proper
down flush with the engine block.
diameter of 1.7498 to 1.7500 inch.
b.
Installation.
Replace piston pins with a diameter
(1)
Refer to figure 29 and install the
smaller than 1.7495 inch.
piston and connecting rod assemblies
(9)
Inspect the connecting rod bushings
on the engine.
for scoring, scratches, and other
indications of wear and damage.
Note. Check connecting rod bearing
Measure their diameter with a pair of
clearances by inserting a piece of
inside
Proper
feeler stock, b% in. wide and 0.004
measurements from 1.7503 to 1.7505
.in. thick, lengthwise between the
in. Replace connecting rod bushings
crankshaft and bearing. Install the
that are worn greater than 1.7515 inch
bearing cap and torque to 86 to 95 ft-
in diameter.
lb. A definite drag should be felt
requiring pressure and possible
(10) Clamp the connecting rod and piston
assembly without rings on the
force to move the rod from side-to-
mandrel with an alining fixture, and
side. Remove the cap and bearing
with the connecting rod bearings in
and remove the feeler stock.
place. Check the gap between the
Reinstall cap and bearing and torque
surface plate and the piston along the
to 85 to 95 ft-lb. Check connecting
piston skirt, with the piston held at
rod side clearance on the crankshaft.
several angles to the connecting rod.
Correct clearance is 0.008 to 0.012 in.
If the gap is not the same at all
Check all connecting rod bearing
angles, the connecting rod is twisted
clearances and side clearances in the
and must be replaced.
same manner.
(11) Hold the piston parallel to the
(2)
Install the oil pump (par. 95).
connecting rod and check the gap
(3)
Install the cylinder head and valves
between the piston skirt and the
surface plate. The gap should not
exceed 0.002 in. within a spread of
(4)
Install the engine housing (TM 53820-
any 4 in. on a given plane.
20520/2).
(12) Inspect the connecting rod and cap for
(5)
Install the engine assembly (par. 30).
cracks, breaks, or other damage.
Section XVII. CAMSHAFT, BEARINGS, TAPPETS, AND TAPPET GUIDES
gear which is an integral part of the camshaft. This gear
100. General
is supported by its own bearing to compensate for side
The camshaft used in this engine is a solid, one-
thrust developed by the action of the gear as it drives
piece shaft. It is supported by four evenly spaced,
the tachometer drive. The cams lift flat-faced tappets,
sleeve-type bearings.
The bearings ace precision
which move in tappet guides that are pressed into the
bushings which are pressed into the block bearing
block.
supports. At the center of the camshaft there is a helical
AGO 3456A
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