FIGURE
53.
MEASURING BEARING CLEARANCE WITH
PLASTIGAGE
Plastigage on the part to which it has adhered and
compare the widest point with thegraduations on the
Plastigage envelope to determine bearing clearance.
1.
2.
3.
4.
5.
CYLINDER
BLOCK
inspection:
Make
a
thorough check for cracks. Minute cracks
may be detected by coating suspected area with a
6.
Reading
A
compared to C and reading
B
com-
pared to
D
indicates whether
or
not the cylinder is
out of round.
If cylinder is out
of
round
0.002
inch
(0.051
mm),
rebore and hone cylinders
for
next oversize
piston.
mixture light motor of
25
oil. percent Wipe the kerosene part dry and and immediately
75
percent
lL7Z,.
k
.\
apply a coating
of
zinc oxide (white lead) dissolv-
ed in wood alcohol.
If
cracks are present, the
white coating will become discolored at defective
area.
Inspect cylinder bore
for
scoring. Check Welsh
plugsfora tight, even fit and the finsfor breakage.
Check cylinder bore for taper, out
of
round and
wear with a cylinder bore gauge, telescopegauge
or inside micrometer, Figure
54.
These
measurements should be taken at four places
-
near top and bottom of piston ring travel.
Referring to Figure54, measure cylinderdiameter
and record the readings as follows:
a. Measure reading
A
across top of cylinder
b. Measure reading
B
across cylinder at bottom
c. Measure reading
C
across
top
of
cylinder
TOP
END
OF
CYLINDER
where greatest piston ring wear occurs.
of piston ring travel.
where greatest ring wear occurs.
of
piston ring travel.
d. Measure reading
D
across cylinder at bottom
8418
BOTTOM
OF
RING
TRAVEL
Compare reading
A
with reading
B,
then compare
reading C with reading
D
to determine cylinder
taper due to wear.
If
taper exceeds
0.005
inch
(0.127
mm), rebore
and hone cylinder to accommodate the next
oversize piston.
FIGURE
54.
CYLINDER BORE MEASUREMENT
52
Redistribution or publication of this document
by any means, is strictly prohibited.
Redistribution or publication of this document
by any means, is strictly prohibited.
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