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140 ENGINE
6A1-25
Fig.
6A1-68
Gauging Plastic On Crankpin
CAUTION: Do not turn the crankshaft with the
gaging plastic instalIed.
Fig.
6A1-69
Measuring Gauging Plastic
d. Remove the bearing cap and, using the scale on the
aging plastic envelope, measure the gaging plastic width at
he widest point (Fig. 6A1-69).
6. If the clearance exceeds suecifications, select a new,
correct size, bearing and remeasire the clearance.
7. Coat the bearing surface with oil, install the rod cap
and torque nuts to 35 lbs. ft.
8. When 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 the connecting rod cap and side of
crankpin (Fig. 6A1-70).
Fig.
6A1-70
Measuring Connecting Rod Side Clearance
M A I N BEARINGS
Main bearings are of the precision insert type and do not
use shims for adjustments. If clearances are found to be
excessive, a new bearing (both upper and lower halves) will
be required. Bearings are available in standard size and .00 1
",
.002", .010" and .020n undersize.
Selective fitting of both rod and main bearing inserts is
necessary in production in order to obtain proper oil
clearances. For this reason you may find one half of a
standard insert with one half of a .001" undersize insert which
will decrease the clearance
.0005"
from using a full standard
bearing.
NOTE: If, for any reason, main bearing caps are
replaced, shimming may be necessary. Laminated shims
for each cap are available for service. Shim requirement
will be determined by bearing clearance.
Inspection
In general, the lower half of the bearing, except No. 1
bearing, shows a greater wear. If upon inspection the lower
half is suitable for use, it can be assumed that the upper half
is also satisfactory. If the lower half shows evidence of wear
or damage, both upper and lower halves should be replaced.
Never replace one half without replacing the other half.
Checking Clearance
To obtain the most accurate results with a wax-like
plastic material which will compress evenly between the
bearing and journal surfaces without damaging either surface,
certain precautions should be observed. If the engine is out
of the car and upside down, the crankshaft will rest on the
upper bearings and the total clearance can be measured
between the lower bearing and journal. If the engine is to
remain in the car, the crankshaft should be supported both
front and rear to remove the clearance from the upper
bearing. The total clearance can then be measured between
the lower bearing and journal.
NOTE: To assure the proper seating of the crankshaft,
all bearing cap bolts should be at their specified torque.
In addition, before checking fit of bearings, the surface
of the crankshaft journal and bearing should be wiped
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