TM 5-3810-295-34
Figure 14-35. Connecting rod specifications.
(4) Check crankpin bore. Bore inside diameter
must be 3.3153.3168 inches. Out-of-round limits
shall not exceed 0.0015 of an inch (4, fig. 14-35). If
either dimensions is not met, rod must be resized.
(5) Check rod bolts. Discard bolts if smallest
diameter is less than 0.478 inch or if pilot diameter is
less than 0.5637 inch. Discard all bolts and nuts that
have distorted threads.
(6) Assure that bolt head rests squarely on milled
surfaces on rod.
(7) Check rod hole pilot inside diameter in rod and
cap. If diameter exceeds 0.5645, discard rod and cap.
(8) Check rod bearing shell thickness, discard
shells that are less than 0.09295 inch.
e. Inspect pistons as follows:
(1) Check for ring groove clearance. Hold new ring
flush with piston land and insert 0.006-inch feeler
gauge. If gauge enters groove without forcing or dis-
engaging ring, wear is excessive and piston must be
replaced.
() Check piston ring gap by inserting each ring in
mating cylinder liner, seating it squarely with piston
head in ring travel area of liner. Measure ring gap with
a feeler gauge. Gap shall be 0.017--0.027 inch for top
ring, 0.013-- 023 inch for intermediate ring and
0 010--.020 inch for lower ring. If necessary, file end
of rings to obtain minimum gap.
CAUTION
Never file chrome plated piston rings.
(3) Check piston skirt diameter with micrometers
at right angles to piston pin bore. Skirt diameter shall
be a minimum of 5.485 inches when measured at 70 F.
(4) Check piston pin bore and piston pin outside
diameter. Piston pin bore shall not exceed 1.750 inches.
Piston pin diameter shall not be less than 1.7478 in-
ches. Piston pins shall not be reused if out-of-round
more than 0.001 inch.
NOTE
Reboring of piston pin bores and use of over-
sized pins is not practical because the
misalignment will cause seizure of piston or
failure of connecting rod bearings.
14-33. Repair
a. Damper is not subject to repair, if inspection
shows it to be defective; install new damper
b. A minimum fillet must be present at all corners
where rod is milled for bolt head, A sharp corner al bolt
pad will contribute to rod breakage (see fig. 14-35).
(1) Piston fillets by milling bolt pad radius t.o
0 250-0 270 inch and the seat radius to 0.046--0.060
inch.
(2) Nicks or dents less than one-sixteenth of an
inch deep shall be removed by grinding with a one-half
14*35
