Chevrolet 1977 light duty truck, Service Manual

Page: 510 / 861

3. Install oil pan previously outlined.
C O N N E C T IN G ROD B EA R IN G S
C onnecting rod bearings are o f the precision insert
type and do not utilize shims for adjustm ent. DO N O T
FILE R O D S O R R O D CAPS. If clearances are found to
be excessive a new b earin g will be required. Bearings are
available in sta n d a rd size an d .001" and .002" undersize
for use with new and used sta n d a rd size crankshafts, and
in .010" and .020" undersize for use with reconditioned
crankshafts.
Inspection and R eplacem ent
1. W ith oil p a n and oil p u m p removed, remove the
connecting rod cap an d bearing.
2. Inspect the bearing for evidence o f w ear or
d am age. (Bearings showing the above should not be
installed.)
3. W ipe the bearings and crankpin clean o f oil.
4. M easure the crankpin for out-of-round or taper
with a micrometer. If not w ithin specifications replace or
recondition the crankshaft. I f w ithin specifications and a
new b earin g is to be installed, measure the m axim um
d ia m e te r o f the c ra n k p in to determ ine new bearing size
required.
5. If w ithin specifications measure new or used
b e a rin g clearances with Plastigage or its equivalent.
N O T E : If a bearing is being fitted to an out-of­
round crankpin, be sure to fit to the m axim um
d ia m e te r o f the crankpin. I f the bearing is fitted to
the m in im u m d iam eter and the crankpin is out-of-
round .001" interference between the bearing and
crankpin will result in rapid bearing failure.
a. Place a piece o f gauging plastic the full width
o f the crankpin as contacted by the bearing (parallel to
the crankshaft) (fig. 6A-56V).
b. Install the bearing in the connecting rod and
cap.
c. Install the bearing cap and evenly torque nuts
to specifications.
CAUTION: Do not turn the crankshaft with the
gauging plastic installed.
d. Remove the bearing cap and using the scale
on the gauging plastic envelope, m easure the gauging
plastic width at the widest point (fig.6A-57V).
6. If the clearance exceeds specifications, select a
new, correct size, bearing and rem easure the clearance.
7. Coat the bearing surface with oil, install the rod
cap and torque nuts to specifications.
8. W hen all connecting rod bearings have been
installed tap each rod lightly (parallel to the crankpin) to
make sure they have clearance.
9. Measure all connecting rod side clearances (see
specifications) between connecting rod caps (fig. 6A-58V).
M A IN B E ARING S
M ain bearings are o f the precision insert type and
do not utilize shims for adjustm ent. If clearances are
found to be excessive, a new bearing, both upper and
lower halves, will be required. Bearings are available in
stan d ard size and .001", .002", .009", .010" and .020"
undersize.
Selective fitting o f both rod and m a in bearing