TM 55-1930-209-14&P-21
(d) Install opposite pin bushing in a similar manner.
NOTE
The bushings must withstand an end load of 1800 pounds without moving after
installation.
(4)
Refer to Table 1-1 and ream piston pin bushings as necessary.
(5)
Fit pistons in cylinder liners as follows:
(a) Refer to Table 1-1 and measure the piston skirt diameter and cylinder liner bores. Take these
measurements with piston and liner at normal room temperature (70°F). Measure lengthwise and crosswise to piston pin
bore. Out-of-round diameter must not exceed .0005 inch.
(b) Refer to Table 1-1 and check piston to liner clearance. Check this in four places, 90* apart while
holding piston upside down in cylinder liner.
(c) Insert appropriate feeler gage between piston skirt and cylinder liner. Attach spring scale to feeler
gage and slowly pull gage from between piston and liner.
NOTE
Watch spring scale reading while pulling feeler gage out. A reading of six pounds
indicates that clearance is thickness of feeler gage plus .001 inch. Feeler gage must be
flat and free of nicks and bends. Piston skirt to cylinder clearance must be greater than
.003 inch and less than .010 inch.
(6)
Fit piston rings as follows:
NOTE
Use new piston rings whenever a piston is removed for inspection or replacement.
(a) Refer to Table 1-1 and measure gap between ends of piston rings before placing rings on piston.
(b) Insert piston rings into cylinder liner, far enough in bore to be on normal wiping area of ring. Measure
ring gap with a feeler gage. Gap must be between .020 and .046 inch for compression rings and .010 to .025 inch for oil
rings. Make sure ring is parallel to top of liner.
(c) If piston ring gap is below clearance specified in Table 1-1, file or stone end of piston ring. File or
stone ring in such a direction that file or stone will cut from outside (chrome plated) surface of ring toward inside surface.
This will prevent chipping or peeling of chrome plate. Ends of ring must remain square and chamfer must be
approximately 0.0015 inch on outer edge.
(7)
Check ring side clearance in piston groove. Clearances are contained in Table 1-1.
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