7-8
PISTONS, RINGS, AND CONNECTING
RODS
PISTON
Specification English Std. Metric
Piston Diameter 3.1220 79.2988
3.1235 79.3369
Pin (Piston) Diameter .6248 15.870
Piston Pin .6251 15.878
Bore Diameter .6257 15.893
Piston Ring Grooves .0645 1.638
Top and Center .0665 1.689
Piston Ring Groove .1255 3.189
Bottom .1275 3.239
Clean all carbon from the piston top and the ring grooves
before measuring. Visually inspect the piston skirt area
for scoring or scratches. If scoring or deep scratches
are evident, replace the piston. The pistons should be
checked for wear by measuring near the bottom of the
skirt 90 degrees from the piston pinhole. (Illust. 7-23)
If the cylinder bore needs re-sizing, an oversize piston
will be necessary. Oversize pistons are identified by the
decimal oversize value imprinted on the top of the piston.
(Illust. 7-24)
INDICATES .010
OVERSIZE PISTON
7-23
PISTON MEASUREMENTS ARE TAKEN AT
BOTTOM OF SKIRT 90
0
FROM WRIST PIN HOLE
7-24
Check the piston ring, side clearance using a feeler gauge
and a new ring. (Illust. 7-25)
7-25
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