Jeep UNIVERSAL CJ-2A - Page 71

E
F4-134 ENGINE
with the oil hole in the block, and that the bearing
lock fits properly in the notch in the block. Install
the crankshaft if replacing bearings with the engine
out of the vehicle. The desired running fit (dif-
ference
between the diameter of the crankshaft
journal and the inside diameter of the fitted bear-
ing) for a main bearing is .0003
11
to .00 2 9
11
[ .0008
a .0074 mm.]. With a dimension in excess of this
standard running fit, a satisfactory bearing replace-
ment· cannot be made and it will be necessary to
regrind the crankshaft. Install the bearing lower
half and the bearing cap and draw the nuts down
equally and only slightly tight. Rotate the crank-
shaft by hand to be sure it turns freely without
drag. Pull the nuts tighter, first one then the other,
a little at a time, intermittently rotating the crank-
shaft by hand until the recommended torque of
35 to 45 lb-ft. [4,8 a 6,2 kg-m.] is reached. If the
bearings are of the correct size, and lubricated with
light oil before .installation, the crankshaft should
turn freely in the bearings. If the crankshaft cannot
be turned, a larger bearing is required. If there is no
binding or tightness, it is still necessary to check
clearance to guard against too loose a fit. Never file
either the bearing cap or the bearing to compensate
for too much clearance. Do not use shims under a
bearing cap or behind a bearing shell. Do not run a
new bearing half with a worn bearing half. The use
of "Pla&tigage" of the proper size to measure .001"
[0,025 mm.] clearance is recommended for check-
ing crankshaft main bearing clearance. The method
of checking clearance is as follows:
a. Remove the bearing cap and carefully wipe
all oil from the bearing and the journal.
b. Lay a piece of "Plastigage" Ys
11
[3 mm.]
shorter than the width of the bearing across the
journal (lengthwise of the crankshaft).
c. Install the bearing and cap and tighten first
one nut, then the other, a little at a time to the
specified torque. As the bearing tightens down
around the journal, the "Plastigage" flattens to a
width that indicates the bearing clearance.
d. Remove the cap and measure the width of
the flattened "Plastigage," using the scale printed
on the edge of the envelope. The proper size "Plasti-
gage" will accurately measure clearance down to
.001
11
•
e. If the flattened "Plastigage" tapers toward
the middle, or toward the end, or both ends, there
is a difference in clearance, indicating a taper, a
low spot, or other irregularity of the bearing or
journal.
E-47. Fitting Crankshaft Main tsearings
Using Shim Stock
Thin feeler or shim stock may be used instead of
"Plastigage" to check bearing clearances. The
method is simple, but care must be taken to protect
the bearing metal surface from injury by too much
pressure against the feeler stock.
a. Cut a piece of .001
11
[0,025 mm.] thick, by
;Y2
11
[12,7 mm.] wide, feeler stock Ys
11
[3 mm.]
shorter than the width of the bearing. Coat this
feeler stock with light engine oil and lay it on the
bearing in the cap, as shown in Fig. 86. With the
70
shim in this position, install the bearing and cap
on the crankshaft.
10442
FIG. 86-SHIM STOCK IN POSITION ON
MAIN BEARING
1-0.001" Feeler Stock Yz" Wide
b. Tighten the bearing cap nuts, first one and
then the other, a little at a time to 35 to 45 lb-ft.
torque [4,8 a 6,2 kg-m.].
c. Turn the crankshaft by hand not more than
one inch in either direction.
Caution: Turning the crankshaft more may imbed
the shim stock in the bearing, giving a false indica-
tion of fit and damaging the bearing.
If the bearing clearance is correct, the piece of .001"
feeler stock should produce a light to heavy drag.
If there is little or no drag the bearing fit is too
loose. If the crankshaft will not turn there is not
enough clearance. In either case another bearing
must be selected to provide the proper fit.
d. After the bearing has been correctly fitted,
remove the shim stock, wipe the bearing and
journal carefully and apply clean engine oil to the
surfaces. Replace the cap and tighten the nuts
fir&t one, then the other, a little at a time, to the
prescribed torque. The crankshaft should now turn
freely without drag.
E-48. Connecting Rod Bearings
The connecting rod bearings, like the crankshaft
main bearings, are of the replaceable type. When
correctly installed, the bearings provide proper
clearance without filing, boring, scraping, or
shimming.
Main bearings with maximum wearing surfaces
are obtained through the use of offset connecting
rods. When the rods are installed, the offset "A"
in Fig. 87 is placed away from the nearest main
bearing "B".
The oil spray hole should be on the "follow" side
or away from the camshaft, toward the right side
of the vehicle. Because of the offset and oil spray
hole, No. 1 and 2 or No. 3 and 4 connecting rods
cannot be interchanged for if they are reversed,
the oil spray hole will be on the wrong side. No. 1
and 3 or No. 2 and 4 can be interchanged.
Connecting rod bearings should be replaced as a
complete set. Each bearing consists of two halves.
Connecting rod bearing sets are available in stand-
ard size and the following undersize:
.001
11
[0,025 mm.) .012
11
[0,304 mm.]
.002
11
[0,050 mm.] .020
11
[0,508 mm.]
.Q10
11
[0,254 mm.] .030
11
[0,762 mm.]