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NOTE: The oil flow described applies only with
S.A.E. 30 oil at normal temperatures and an air
gauge pressure of 25 pounds.
NOTE: It is usually necessary to reposition the
crankshaft for each bearing so that the leakage
from the bearing you observe can be properly
segregated and not confused with the leakage
from another point.
9. After all bearings have been checked the shut-off
valves (A) and (E) should be closed (to relieve
pressure in the lines), before being disconnected
from the air source and engine.
CAUTION: If it is necessary to refill the tank
during the checking operation, the tank must be
relieved of pressure before removing filler plug
(H).
MAIN BEARINGS - PAGE 3-16
(6 CYLINDER)
INSTALLATION:
Recommended main bearing clearance is 0.0005"
to 0.0015". These close clearances must be main-
tained when fitting new bearings.
One method for checking bearing clearance is as
follows:
1. Inspect the crankshaft for scoring, out of round
and taper. Crankshafts with journals that have
more than .001" taper or out-of-round, should be
reground or replaced.
2. Install all bearings and bearing caps and tighten
all bearing cap screws to 75-lbs. torque.
3. Rotate crankshaft by hand, if crankshaft can be
turned by hand one complete revolution; bearing
to journal clearance is at least .0005". If crank-
shaft cannot be turned by hand; bearing fit is too
tight.
4. If crankshaft turns too freely, check for loose
bearings working one bearing at a time by plac-
ing a piece of brass shim stock .002" thick, 1/2"
wide and 1" long between the bearing face and
the crankshaft journal, Figure 4.
FIGURE 4
5. Oil the shim freely with light engine oil and install
the bearing and bearing cap to the block with the
shim equally spaced on the bearing. Tighten to 75
foot lbs.
6. Rotate the crankshaft one-half turn by hand; if the
crankshaft drags or if the crankshaft cannot be
turned by hand with a .002" shim in place, but
turns freely without the .002" shim it indicates
that the clearance is more than 0.0005" and less
than 0.0015" and that the standard size bearing
can be used. If however the crankshaft t u r n s
freely without any drag, it indicates that the
bearing which has the .002" shim stock is too
loose.
7. If bearing is too loose in paragraph 6, remove the
.002" shim and insert a .003" shim as a checking
gauge; now if bearing drags when crankshaft is
turned by hand a .001" undersize bearing can be
used.
NOTE: The same procedure can be used for
checking .002", .010" or .012" undersize bear-
ings keeping in mind that the .0005" to .0015"
clearance must be maintained.
5
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