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9 - 6
ENGINE
BEARING CAP
PLASTIC-GAGE
BEARING
SHELL
PLASTIC-GAGE
H I
mill
i
MM
m
m
J8909-59
Fig. 2 Placement of Plastigage in Bearing Shell
remove t h e clearance between upper bearing shell
and t h e crankshaft. T h i s c a n be accomplished b y
placing a m i n i m u m o f 0.254 m m (0.010 inch) s h i m
between t h e bearing shell and t h e bearing cap o n the
adjacent bearings a n d t i g h t e n i n g t h e bolts t o 14-20
N»m (10-15 ft. lbs.) torque.
• W h e n checking N o . 1 m a i n bearing; s h i m # 2
m a i n bearing.
• W h e n checking N o . 2 m a i n bearing; s h i m # 1 &
# 3 m a i n bearing.
• W h e n checking N o . 3 m a i n bearing; s h i m # 2 &
# 4 m a i n bearing.
• W h e n checking N o . 4 m a i n bearing; s h i m # 3 &
# 5 m a i n bearing.
• W h e n checking N o . 5 m a i n bearing; s h i m # 4
m a i n bearing.
• W h e n checking N o . 4 m a i n bearing; s h i m N o . 3
m a i n b e a r i n g (3.9 E n g i n e only).
A l l s h i m s m u s t b e r e m o v e d
before r e a s s e m -
bling engine.
A L T E R N A T I V E
M E T H O D - T h e
weight o f t h e
crankshaft i s supported b y a j a c k under t h e counter-
weight adjacent t o t h e b e a r i n g being checked.
(3) Place a piece o f Plastigage across t h e entire
w i d t h o f t h e bearing shell i n t h e cap approximately
6.35 m m (1/4 inch) off center a n d away from t h e o i l
holes ( F i g . 2). I n a d d i t i o n , suspect areas c a n be
checked b y placing t h e Plastigage i n t h e suspect
area. T i g h t e n the b e a r i n g cap bolts o f the bearing be-
i n g checked t o 115 N»m (85 f t . lbs.) torque.
The checking of connecting r o d clearances does not
require s h i m m i n g o f t h e crankshaft. However, before
assembling t h e r o d cap w i t h Plastigage i n place, t h e
J8909-60
Fig. 3 Clearance Measurement
crankshaft m u s t be t u r n e d u n t i l t h e connecting r o d
to be checked starts m o v i n g t o w a r d t h e top o f t h e en-
gine. O n l y t h e n should t h e cap be assembled a n d
tightened t o 6 1 N»m (45 f t . lbs.) torque. Do n o t rotate
t h e crankshaft w h i l e assembling t h e cap or t h e Plas-
tigage m a y be smeared, g i v i n g inaccurate results.
(4) Remove t h e bearing cap and compare t h e w i d t h
of the flattened Plastigage w i t h t h e metric scale pro-
vided on t h e package (Fig. 3). Locate t h e band closest
to t h e same w i d t h , t h i s band shows t h e a m o u n t o f
clearance i n thousandths o f a m i l l i m e t e r . Differences
i n readings between t h e ends indicate t h e a m o u n t o f
taper present. Record a l l readings t a k e n . Refer t o
Engine
Specifications
i n t h i s section.
P l a s t i g a g e
g e n e r a l l y
i s a c c o m p a n i e d
b y t w o s c a l e s . O n e
s c a l e i s i n i n c h e s , the other i s a m e t r i c s c a l e .
(5) Plastigage i s available i n a v a r i e t y o f clearance
ranges. T h e 0.025-0.076 m m (0.001-0.003
inch) i s
usually t h e most appropriate for checking engine
bearing clearances.
REPAIR OF DAMAGED OR WORN THREADS
Damaged o r w o r n threads can be repaired. Essen-
t i a l l y , t h i s repair consists of d r i l l i n g o u t w o r n or
damaged threads, t a p p i n g t h e hole w i t h a special
H e l i - C o i l Tap, (or equivalent), a n d i n s t a l l i n g a n i n -
sert i n t o t h e tapped hole. This brings t h e hole back
to i t s o r i g i n a l t h r e a d size.
CAUTION: Be sure that the tapped holes maintain
the original centerline.
Heli-Coil tools a n d inserts are readily
available
from automotive parts jobbers.
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