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ENGlN E M - C Y Ll NDER
9-2 1
Fig. 42-Removing
and Installing Upper M a i n
Bearing fTool C-30591
changeable.
The NO. 3 upper and lower main bear-
ings are flanged to carry the crankshaft thrust loads
and
are not interchangeable
with any other main bear-
ings in the engine.
Bearings that are not badly worn,
scored or pitted should be reinstalled in the same
bearing bore.
The bearing caps are not interchangeable and the
numbers should be marked at removal to insure cor-
rect assembly. Bearings are available in standard and
the following undersizes: .001, .002, .003, .010 and
.012 inch. Never install an undersize bearing that will
reduce the clearance below specifications.
Removal
(1)
Remove the oil pan and inspect the bearing cap
numbers.
(2) Remove bearing caps one at a time. Remove up-
per bearing by inserting Tool C-3059 (Fig. 42) into
the oil hole on the crankshaft.
(3) Slowly rotate the crankshaft clockwise, forcing
out the upper bearing.
MEASURING THE MAIN
BEARING CLEARANCE
Shim Stock Method
(1) Position the crankshaft in block.
(2) Smooth the edges of a
1/2
x
%
inch piece of soft
copper or brass shim stock, .001 inch thickness.
(3) Lubricate the main bearing journals and posi-
tion the shim stock across the center main journals.
(4)
Install the bearing in the center main bearing
cap, bearing tang in groove on cap, lubricate bearing
and seat cap on block. Tighten bolts to
85
foot-
.FAA,
\
I U U L l
TOOL
SIDE
SEXL
GROOVES
LWu
NY133
Fig. 43-Installing
Rear Main Bearing
Oil Seal
(Tool
C-37431
pounds torque.
(5) If a slight drag is felt as the crankshaft is
ro-
tated, not over ?4 turn in either direction the clear-
ance is .001 inch
or
less and is considered satisfac-
tory.
If however, no drag is felt, the bearing is too large
or the crankshaft cannot be rotated, the bearing is
too small and should be replaced with the correct
size.
It is permissible to use one .001 inch undersize
bearing shell with one standard bearing shell, or one
.002 inch undersize bearing shell with one .001 inch
undersize shell. Always use the smaller diameter bear-
ing half as the upper. Do not use a new bearing with
a used bearing and never use an upper bearing half
more than .001 inch smaller than the lower bearing
half.
(6)
Fit the remaining bearings in the same manner.
(7) Measure the crankshaft end play to
,002-.007
TOOL
Fig. 4&-Trimming
Rear M a i n Bearing
Oil Seal
(Tool C-37431
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