Pisfon Rings:
1. Install the piston ring in the cylinder bore. Invert
the piston and push the ring to the end of ring
travel, about halfway into the bore. This trues the
ring end gap. Check the gap with a feeler gauge
(Figure
68).
2.
The practice of filing ring ends to increase the
end gap is not recommended. If the ring end gap
does not meet specifications, check for the cor-
rectness of ring and bore sizes.
A
cylinder bore
that isO.001 inch
(0.03
mm) undersizewill reduce
the end gap
0.003
inch
(0.08
mm).
FIGURE
68.
POSITIONING
OF
PISTON RING
AND MEASURING
OF
END GAP
CYLINDER
BLOCK
The cylinder block is the main support for all other
basic engine parts. Crankshaft and camshaft are
supported by the block, assuring alignment
of
the
crankshaft and cylinder bores.
Cleaning
After removing pistons, crankshaft, cylinder heads,
etc., inspect block for cracks and extreme wear. If
block is still serviceable, prepare
it
for cleaning as
follows:
1.
Scrapeall old gasket material from block. Remove
oil by-pass to allow cleaning solution to contact
inside of oil passages.
2.
Remove grease and scale from cylinder block by
agitating in a bath of commercial cleaning solu-
tion or hot soapy washing solution.
3.
Rinse block in clean hot waterto removecleaning
solution.
1
Inspection
When rebuilding theengine, thoroughly inspect block
for any condition that would make it unfit for further
use. This inspection must be made after all parts have
been removed and block has been thoroughly cleaned
and dried.
1.
Make a thorough check for cracks. Minute cracks
may be detected by coating the suspected area
with a mixture of
25
percent kerosene and
75
percent light motor oil. Wipe the part dry and
immediately apply a coating of zinc oxide (white
lead) dissolved in wood alcohol. If cracks are
present, the whitecoating will become discolored
at the defective area. Always replace a cracked
cylinder block.
2.
Inspect all machined surfaces and threaded holes.
Carefully remove any nicks or burrs from ma-
chined surfaces. Clean out tapped holes and
clean up any damaged threads.
3.
Check top of block for flatness with a straight
edge and a feeler gauge.
Cyjinder Bore
Inspection:
Inspect cylinder bores for
scuffing, scratches, wear, and scoring. If cylinder
bores are scuffed, scratched, scored, or worn, they
must be rebored and honed for the next oversize
piston.
When the appearance of cylinder bores is good and
there are no scuff marks, check cylinder bore for wear
or out of roundess as follows:
1.
Check cylinder bore for taper, out of round, and
wearwith a cylinder bore gauge, telescope gauge
or inside micrometer. These measuremets should
be taken at four places, top and bottom
of
piston
ring travel, parallel and perpendicular
to
axis of
crankshaft.
2.
Record measurements taken at top and bottom
of
piston travel as follows (Figure
69):
48
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