User Manual

200 BENCH PROCEDURES
Page 5-9
Figure 5-6 — Connecting Rod Fixture
Maximum twist of connecting rod within 12 inches
(30.5 cm) is 0.010 inch (0.254 mm). The
maximum bend of connecting rod within
12 inches (30.5 cm) is 0.004 inch (0.102 mm).
Distances are center to center.
[212 HP] CRANKSHAFT
Description
The crankshaft is fully counterbalanced and
journals are induction-hardened. There are seven
main bearings. Thrust washers located at the
center main bearing (position No. 4) absorb fore
and aft end thrust. Crankshaft extension at
forward end carries the main drive gear, vibration
damper and accessory drive pulleys. The main
drive gear has a shrink fit and the vibration
damper hub has a press fit. The main drive gear
is keyed to the crankshaft and proper assembly is
important for engine timing. The flywheel is
mounted to a flange at rear of crankshaft. Two
seals, one at the front and one at the rear,
prevent engine lubricating oil from leaking around
ends of the crankshaft.
Bearing caps are furnished with the crankcase
and support the crankshaft in true alignment.
Webs integral to the crankcase provide upper half
of main bearing supports. Removable caps
provide lower support. Capscrews hold the
caps in position. The bearing caps are not
interchangeable and each has a number stamped
on it which signifies its correct location and
alignment in the crankcase. The caps are
numbered 1 through 7, with No. 1 main bearing
cap in front of engine. The bearing inserts are
precision designed. Bearings are inserted
between the crankshaft and crankcase, and
between the crankshaft and bearing caps. Thrust
flanges to support thrust washers are located at
the center main bearing (No. 4).
Extreme care must be taken to guarantee
cleanliness of crankcase, crankshaft, and
bearings during servicing and after service has
been completed. Whenever possible, crankshaft
should be removed when bearings are being
installed in order to clean crankcase thoroughly.
All bearing surfaces must be free of grit and
burrs. Small particles of dust and dirt left between
crankshaft and bearings will cause rapid wear
and scoring of crankshaft journal and inserts. Any
foreign material left between bearings and
crankshaft bearing caps will cause distortion of
bearing and a reduction in operating clearance at
that point. The resulting frictional heat will cause
bearing material to melt away from steel backing
of bearing at that point. Such melted material will
create further hot spots until complete bearing
failure occurs. Anything that interferes with
operating clearance of any bearing, or proper
heat dissipation, affects bearing life. Cleanliness
cannot be overstressed.
200329a
5-101.bk Page 9 Friday, March 17, 2006 11:05 AM