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ENGINE
9 - 5
test, i t could indicate t h e existence o f a problem i n
the cylinder i n question.
T h e r e c o m m e n d e d
c o m p r e s s i o n
p r e s s u r e s
a r e t o b e u s e d o n l y a s a g u i d e t o d i a g n o s i n g
e n g i n e p r o b l e m s . A n e n g i n e s h o u l d N O T b e
d i s a s s e m b l e d t o d e t e r m i n e t h e c a u s e o f l o w
c o m p r e s s i o n
u n l e s s
s o m e
m a l f u n c t i o n
i s
p r e s e n t .
(5) Clean or replace s p a r k plugs as necessary and
adjust gap. See Group 8 D , I g n i t i o n System for gap
adjustment and torque.
(6) Test resistance o f spark p l u g cables. Refer t o
Group 8D, I g n i t i o n System.
(7) Inspect the p r i m a r y w i r e . Test coil output volt-
age, p r i m a r y and secondary resistance. Replace parts
as necessary. Refer t o Group 8D, I g n i t i o n System and
make necessary adjustment.
(8) Reset i g n i t i o n t i m i n g to specifications (see Spec-
ification Label on engine compartment hood).
(9) Perform a combustion analysis.
(10) Test fuel p u m p for pressure and vacuum. Refer
to Group 14, F u e l System for the proper specifica-
tions.
(11) Inspect m a n i f o l d heat control valve i n the en-
gine
exhaust m a n i f o l d for proper
operation (see
Group 0, L u b r i c a t i o n a n d Maintenance for the proper
procedure). A p p l y M a n i f o l d H e a t C o n t r o l Valve Sol-
vent t o the b u s h i n g and shaft.
(12) Inspect a i r f i l t e r element (see Group 0, L u b r i -
cation and Maintenance for t h e proper procedure).
(13)
Inspect
crankcase
v e n t i l a t i o n system (see
Group 0, L u b r i c a t i o n a n d Maintenance for the proper
procedure).
(14) For emission controls see Group 25, Emission
Controls System for service procedures.
(15) Inspect and adjust accessory b e l t drives (refer
to Group 7, Cooling System for t h e proper adjust-
ments).
(16) Road test vehicle as a f i n a l test.
HONING CYLINDER BORES
Before honing, stuff p l e n t y o f clean shop towels u n -
der t h e bores and over t h e crankshaft t o keep abra-
sive m a t e r i a l s f r o m e n t e r i n g the crankshaft area.
(1) Used carefully, the cylinder bore sizing hone C-
823 equipped w i t h 220 g r i t stones, i s t h e best tool for
t h i s job. I n a d d i t i o n t o deglazing, i t w i l l reduce taper
and out-of-round as w e l l as r e m o v i n g l i g h t scuffing,
scoring or scratches. U s u a l l y a few strokes w i l l clean
up a bore and m a i n t a i n t h e required l i m i t s .
(2) Deglazing of the c y l i n d e r walls m a y be done us-
i n g a cylinder surfacing hone, Tool C-3501, equipped
w i t h 280 g r i t stones (C-3501-3810) i f the cylinder
bore is s t r a i g h t a n d r o u n d . 20-60 strokes, depending
on t h e bore condition, w i l l be sufficient t o provide a
satisfactory surface. U s i n g h o n i n g o i l C-3501-3880 or
Fig. 1 Cylinder Bore Cross-Hatch Pattern
a l i g h t h o n i n g o i l available f r o m major o i l d i s t r i b u -
tors. Do n o t use e n g i n e o r t r a n s m i s s i o n o i l , m i n -
e r a l s p i r i t s o r k e r o s e n e .
(3) H o n i n g should be done b y moving the hone u p
and down fast enough t o get a cross-hatch p a t t e r n .
W h e n hone m a r k s i n t e r s e c t a t 50° to 60°, t h e cross-
hatch angle is most satisfactory for proper seating o f
rings (Fig. 1).
(4) A controlled hone motor speed between 200 and
300 r p m is necessary to obtain the proper cross-hatch
angle. T h e n u m b e r o f u p a n d down strokes per
m i n u t e can be regulated to get the desired 50° to 60°
angle. Faster up and down strokes increase t h e cross-
hatch angle.
(5) A f t e r h o n i n g , i t is necessary t h a t the block be
cleaned again t o remove a l l traces of abrasives.
CAUTION: Be sure all abrasives are removed from
engine parts after honing. It is recommended that a
solution of soap and water be used with a brush
and the parts thoroughly dried. The bore can be
considered clean when it can be wiped clean with a
white cloth remains clean. Oil the bores after clean-
ing to prevent rusting.
MEASURING WITH PLASTIGAGE
Engine crankshaft bearing clearances can be deter-
m i n e d by use of Plastigage or equivalent. The follow-
i n g is t h e recommended procedures for t h e use o f
Plastigage:
(1) Remove o i l f i l m from surface to be checked.
Plastigage is soluble i n o i l .
(2) T h e t o t a l clearance of the m a i n bearings can
only be determined b y removing the weight o f t h e
crankshaft. T h i s can be accomplished by either o f
two methods:
P R E F E R R E D
M E T H O D - S h i m m i n g t h e bear-
ings adjacent to the bearing to be checked i n order t o
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