Service Manual

.Inspection
When rebuilding the engine, thoroughly inspect the
block for any condition that would make
it unfit for
further use. This inspection must be made after all
parts have been removed and the block has been
thoroughly cleaned and dried.
1. Make a thorough check for cracks. Minute
cracks may be detected by coating the
sus-
pected area with a mixture of 25 percent kero-
sene 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 white coating will be-
come 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
machined surfaces. Clean out tapped holes
and clean up any damaged threads.
3. Check the top of the block for flatness with a
straight edge and a feeler gauge.
Cylinder Bore Inspection Inspect cylinder bore
for scuffing, scratches, wear, and scoring.
If cylinder
bore is scuffed, scratched, worn
, or scored, it must
be rebored and honed for the next oversize piston.
When the appearance of the cylinder bore
is good
and there are no scuff marks, check cylinder bore
for wear or
out of roundness as follows:
1. Check cylinder bore for taper, out of round, and
wear with a cylinder bore gauge, telescopic
gauge, or inside micrometer. These measure-
ments should be taken at four places: top and
bottom of piston ring travel, parallel and per-
pendicular
to axis of crankshaft (Figure 11-31).
2. Record measurements taken at top and bot-
tom of piston travel as follows:
A. Measure and record as "A" the cylinder
.bore diameter (parallel to crankshaft) near
the top of cylinder bore.
TOP OF CYLINDER
RING
WEAR
AREA
iBOTTOM OF RING TRAVEL
B-418
FIGURE 11-31. METHODS OF MEASURING THE
DIAMETER OF
A CYLINDER BORE
B. Measure and record as "B" cylinder bore
diameter (parallel to crankshaft) at the bot-
tom of piston travel.
C. Measure and record as
"C" cylinder bore
diameter (perpendicular to crankshaft)
near the top of cylinder bore.
D. Measure and record as "D" cylinder bore
diameter (perpendicular to crankshaft) at
the bottom of piston travel.
E. Reading "A" subtracted from reading "B"
and reading "C" subtracted from reading
"D" indicates cylinder taper.
If cylinder taper exceeds that specified in
Dimensions and Clearances rebore and
hone cylinder to the next oversize.
F. Reading "A" compared to reading "C" and
reading
"B" compared to reading "D" indi-
cate whether or not cylinder
is out of round.
If out of round exceeds that specified in Di-
mensions
and Clearances the cylinders
must
be rebored and honed to the next
oversize.