Hudson 1955 Rambler, Техническое и сервисное руководство

Страница: 37 / 292

10
T E C H N I C A L S E R V I C E M A N U A L
FIGURE 25— Piston and Connecting Rod
Assembly
Connecting Rod Alignment
Whenever new rings are installed or new
piston pins are replaced, it is necessary to
align the connecting rods and pistons as
assemblies to insure true operation in the
cylinder bore.
Misaligned rods will cause uneven piston
and ring wear which will result in oil
consumption. The connecting rod should be
inspected for a twisted or bent condition.
Connecting Rod Bearings
The connecting rod bearings are the steel-
backed, babbitt lined precision type. They
are installed as pairs in the connecting rod
and cap.
CAUTION: Never file a connecting rod
or cap to adjust bearing clearance.
To determine the amount of bearing clear-
ance, use a piece of Plastigage in the
bearing cap. Then tighten the cap to torque
specifications to compress the gauge. Remove
the bearing cap and calibrate the width of
the Plastigage with the scale furnished.
If the bearing clearance is excessive, the
correct undersize bearing insert (pair)
should be installed in the connecting rod.
The correct connecting rod bearing clearance
is .0005" to .0025".
It is important that the connecting rod
bearing cap bolt nuts be drawn up to 40 to
45 foot pounds torque.
CRANKSHAFT
The crankshaft is a precision steel cast shaft
having five main journals, four crankpins, and
provided with an oil stinger at rear journal
inboard of the rear oil seal.
The component parts of the crankshaft assem-
bly are individually balanced, and then the
complete engine assembly is balanced as a unit.
Replacement of crankshaft, flywheel, or vibra-
tion damper can be accomplished without rebal-
ancing the complete assembly.
Main Bearing Journals
Main bearing journals can be measured without
removing the crankshaft from the engine block.
Various gauges are available for this purpose.
Always check both ends of the journal to note
the taper. Then rotate the shaft 90° and measure
for out of round.
The main bearing diameter is 2.500" 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.
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 .0005" to .0025" 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 90 to 95
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