TM 5-4310-343-35
(d) Position counterweights (33) on the crankshaft (40) so that the side with the shortest hole-to-edge
distance faces the cam assembly. Drop lockwashers (35) into recesses in counterweights and insert screw locks (32) on
top. Insert screws (34) and torque to 30 pound inches using torque adapter, part number 256995 or equivalent. If groove
in screw head is not aligned with the groove in counterweight, torque to 55-75 pound-inches to bring into alignment but be
certain screws do not bind or bottom. Tap end of the screw lock into groove in screw head to lock in place.
(e) Temporarily assemble piston pin assembly, to determine selection of shims (28). Assemble piston
pin (26) to piston (29). Install retaining rings (27). Select the necessary shims (28) to limit the piston pin end play to a
minimum while still permitting free rotation. End play should not exceed 0.002 inches. When shims have been selected
and installed, disassemble and tag all parts as this is now a select fit assembly.
(f) Assemble the first stage as follows: Mount crankcase in holding fixture with first stage opening on
top. Rotate the crankshaft until piston pin hole in the cam assembly is as far out of the crankcase as possible (top, center
position). Lead cam out of crankcase while rotating the crankshaft to prevent cam from contacting crankcase which would
damage parts. Remove one stud (7, figure 6-6) from both left and right side of first stage mounting flange. Position piston
(29) over cam assembly with identification mark "F" facing front of crankcase. Insert piston pin (26) shouldered end first,
through one piston opening, through cam assembly opening and into the opposite piston opening. Install preselected
shims (28), and retaining rings (27) being sure that sharp edges of retaining rings face out. Exercise care to prevent
piston from striking the studs in the crankcase.
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