Cleaning
Piston
1. Do not sand blast or glass bead blast piston. Bead
blasting rounds the ring lands and will 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.
2. To remove all carbon and combustion deposits, soak
the piston in a special detergent that will not corrode
aluminum. Maintain the temperature of the cleaning
solution well below 212° F (100° C).
3. Thoroughly rinse the piston and dry with moisture free
compressed air.
4. Thoroughly clean the three piston ring grooves of all
carbon deposits. A broken compression ring properly
ground to a sharp chisel-like edge can be used for this
purpose.
5. Verify that the piston pin lock ring groove is clean and
free of dirt and grime.
6. Clean oil drain back holes leading from the oil control ring
groove to the underside of the piston crown. Use a soft
bristle brush and compressed air to ensure cleanliness.
Do not use a wire brush or the holes may be enlarged.
7. If present, verify that set of oil drain back holes at top of
piston skirt are clean and open.
Connecting Rod
1. Thoroughly clean parts in a non-volatile cleaning solution
or solvent. Follow up with a thorough wash in hot soapy
water.
2. Blow dry with low pressure compressed air.
3. Verify that oil holes in connecting rod shank and at top of
piston pin bore are clean and open.
Inspection
Piston and Pin
1. Carefully inspect the piston for damage or excessive
wear. Proceed as follows:
A. Inspect the piston for cracks. Pay special attention
to the area around the pin bores and oil drain back
holes beneath the piston crown.
B. Check piston for cracked, broken or bent ring lands.
C. Check piston skirt for cracks, gouges, deep
scratches or heavy scoring.
D. Check piston head for evidence of burning, etching
or melting.
E. Look for marks or imprints caused by contact with
valves.
NOTE:
A piston with superficial wear marks, minor
scratching or mild scoring may continue to be used.
2. Lightly oil, with clean engine oil, a good piston pin and
insert it into the piston pin bore to feel for proper fitment.
The pin should slide in and out without binding, but also
without pivoting or rocking.
3. Using an inside micrometer or dial caliper, measure the
piston pin bore diameter at two locations - parallel and
perpendicular to the crankshaft (
A
the piston if either measurement is
0.826 in
(20.970 mm)
or more.
120
4. Using an outside micrometer, measure the outside
diameter of the piston pin at two locations- parallel and
perpendicular to the crankshaft (
B
). Replace piston pin if
either measurement is
0.829 in
(21.063 mm) or less.
5. Run your index finger around the edge of the piston
crown to feel for dings, nicks or burrs. Lightly file the
edge of the crown to remove any defects.
100
Summary of Contents for BIG BLOCK M540000
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