Chevrolet 1977 light duty truck, Руководство по обслуживанию

Страница: 471 / 861

• A figure " 9 " will be stam ped on the block at
the left front oil pan rail.
N O T E : If, for any reason, main bearings caps are
replaced, shim m ing may be necessary. L am in ated
shims for each cap are available for service. Shim
r e q u i r e m e n t will be d e t e r m in e d by b e a rin g
clearance.
Inspection
In general, the lower h a l f o f the bearing (except
N o.l bearing) shows a greater w ear and the most distress
from fatigue. If upon inspection the lower half is
suitable for use, it can be assum ed that the upper half is
also satisfactory. If the lower h a l f shows evidence o f
w ear o r d am age, both u pper an d lower halves should be
replaced. N ever replace one h a lf without replacing the
o th e r half.
Checking Clearance
To obtain the most accurate results with "Plasti-
gage", (or its equivalent) a wax-like plastic material
which will compress evenly between the bearing and
jo u rn a l surfaces w ithout d a m a g in g either surface, certain
precautions should be observed. If the engine is out o f
the vehicle an d upside down, the crankshaft will rest on
the u p p e r bearings and the total clearance can be
m easured between the lower b earin g and journal. If the
engine is to rem ain in the vehicle, the cran k sh aft should
be supported both fro n t and re a r ( d a m p e r and flywheel)
to remove the clearance from the u pper bearing. The
I
Fig. 6A-52--Measuring Gauging Plastic (Typcial)
Fig. 6A-53 -Measuring Crankshaft End Play (Typical)
total clearance can then be measured between the lower
bearing and journal.
N O TE: To assure the p ro p e r seating o f the
cran k sh aft all bearing cap bolts should be at their
specified
torque. In addition, p re p a ra to ry to
checking fit o f bearings, the surface o f the