1956 AMC Hudson Technical Service Manual Supplement

ENGINE V-8 13
The main bearing diameter is 2.4983" to 2.4990" and
should not taper or be out of round more than .002".
Crankshaft Main Bearings
Main bearings are of the precision type having a steel back
with a babbitt lining. The bearings are not adjustable.
Shims should never be used and the bearing caps should
never be filed.
Service bearings are supplied in .001", .002", .010", and
.012" undersize.
When either half of a bearing requires replacement, a
complete set should be installed. To replace the upper half
of a bearing, remove the bearing cap of the bearing to be
replaced. Then loosen all of the other bearing caps and
insert a small pin about 1/2" long in the crankshaft oil
hole. The head of this pin should be large enough so that
it will not fall into the oil hole, yet thinner than the thickness
of the bearing.
With the pin in place, rotate the shaft so that the upper
half of the bearing will rotate in the direction of the locating
tongue on the bearing.
Crankshaft Main Bearing Clearance
The standard clearance of .0006" to .0032" can be accurately
checked by the use of Plastigage.
NOTE: When checking bearing clearance, with the
engine in such a position that the bearing caps
support the weight of the crankshaft and flywheel,
keep all main bearings tight except the one being
checked. Support the weight of the crankshaft with
a jack.
Remove the bearing cap and wipe the oil from the
bearing insert.
Place a piece of Plastigage across the full width of the
bearing insert.
Reinstall the bearing cap and tighten 80 to 85 foot
pounds torque. Then remove the bearing cap and with the
graduated scale, which is printed on the Plastigage envelope,
measure the width of the flattened Plastigage at its
widest point. The number within the graduation indicates
the clearance in thousandths of an inch. Install the proper
size bearing liners (inserts) to bring the clearance to standard.
Grinding of the crankshaft may be required to accommodate
the nearest undersize bearings when cleaning up a
scored bearing surface.
Crankshaft End Play
The crankshaft end thrust of .003" to .007" is taken at the
front or No. 1 bearing insert which is flanged for this
purpose.
To check this clearance, attach a dial indicator to the
crankcase and pry the shaft fore and aft with a screw driver
(Fig. 21).
FIGURE 21—Checking Crankshaft End Thrust
REAR MAIN BEARING OIL SEALS
The rear main bearing oil seal is composed of two hemp
packings, one in the block, the other in the cap.
The packing is driven into place with Tool J-3048-A (Fig.
22). Excess packing is cut off flush with the cap.
FIGURE 22—Installing Hemp Packing Oil Seal
in Rear Main Bearing Cap
VIBRATION DAMPER
The vibration damper is balanced independently and then
rebalanced as part of the complete crankshaft assembly.
Service replacement dampers may be installed without
attempt to duplicate balance holes present in original
damper.