Vanguard BIG BLOCK M540000, Repair Manual, Page: 100 / 168

6. Measure the piston ring side clearance as follows:
NOTE: Worn ring grooves result in high oil consumption
and blow-by of exhaust gases. Blow-by of exhaust gases
contaminates the engine oil supply, and reduces engine
efficiency by weakening the combustion seal necessary for
efficient transfer of energy to the piston.
A. Insert the edge of a new compression ring into the
top piston ring groove. Insert a feeler gauge between
the upper surface of the ring and the ring land (see
Figure 121).
121
B. Since the grooves wear unevenly, repeat this check
at several locations around the piston ring groove
circumference.
C. Discard the piston if any measurement is 0.044 in
(1.11 mm) or more.
NOTE: Only the top compression ring side clearance needs
to be checked.
Connecting Rod
1. Inspect the connecting rod for cracks, twisting or
bending.
2. Inspect bearing surfaces for scratches or scoring.
3. Inspect dipper on connecting rod cap for bending,
chipping, or cracking.
NOTE: Replace connecting rod and cap if any of the
above conditions are found. Always replace connecting
rod and cap as an assembly
4. Install the connecting rod cap to the connecting rod so
that the marks on the connecting rod cap and shank are
aligned (see Figure 122). Start the 2 fasteners by hand,
then tighten to 130 lb-in (14.7 Nm).
122
5. Obtain Telescoping Gauge (see Special Tool List ) and
inside micrometer or plug gauge.
6. Measure piston pin bearing bore diameter at two
locations- parallel and perpendicular to the crankshaft
( A , Figure 123). Replace connecting rod if either
measurement is 0.830 in (21.082 mm) or more.
123
7. Measure the crank pin bearing bore diameter at two
locations- parallel and perpendicular to the crankshaft
( B ). Replace the connecting rod if either measurement is
1.698 in (43.13 mm) or more.
8. Remove two hex flange screws to release connecting rod
cap.
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