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2-30
VALVE SERVICE
ENGINE
(52)
Identiflcation Marks
lower
Upper
o
2 dots
To identify each rocker arm and assist in
installation, an identification mark is formed in
the lower side of bearing boss, and identifica-
tion depressions or dots, or a number, also are
formed in upper side of bearing boss as follows:
2-19 REPLACEMENT OF TIMING CHAIN
AND CRANKSHAFT OIL SEAL
with oil (about 1 minute), stop engine and
immediately tum engine until either No.2 or
No.7 exhaust valve is fully closed.
2. Mount dial indicator to bear against the
valve spring cap of the fully closed exhaust
valve and set indicator at
zero.
See figure 2-26.
3. On
Series
40-50
engine,
slowly turn engine
in running direction only until exhaust valve
opens exactly.
145".
On
Series
70 engine, open
exhaust valve exactly
.155".
NOT E : It is ad-
visable to remove flywhe
el low er
housing so
that
engine
can be
turned
very slow ly by means
of
pinch
bar
applied
to flywh
eel
ring
gear.
4. Remove timing hole cover.
If
the "V.D.C.
1-8" mark on flywheel is visible through the
timing hole, the valve and camshaft timing is
correct.
1
dot
1
Valve Number
Engine
Where Installed
Series
1, 3, 5, 7 Inlet. .
..
40-50-70
2,4, 6, 8 Exhaust. 40-50
2, 4, 6, 8 Inlet
.
. . .40-50-70
1, 3, 5, 7 Exhaust
.
40-50
X
42
All Exhaust. 70
Figures 2-24 and 2-25 show the proper posi-
tion of each valve rocker arm according to the
lower identification mark. In addition to these
identification marks, attention must be given
to the important
differenc es between
rocker
arms and ball studs used with adjustable valve
lash and thos
e
parts us
ed
w
ith
hydraulic val
ve
lifters. See figure
2-10.
2-18 CHECKING VALVE AND
CAMSHAFT TIMING
A timing chain will usually become notice-
ably noisy at idle speed before it has worn to
the extent that valve timing is changed enough
to noticeably affect engine performance. When
it becomes desirable to check valve timing to de-
termine whether the chain has been correctly in-
stalled. it may be done in the following
manner.
Figure 2-26-0ial Indicator Set to Check Valve Timing
1.
On
engine having
adjustable valve lash,
adjust valves for .015" road operating lash
(par. 2-14), stop engine and turn until either
No.2 or
No.7
exhaust valve is fully closed.
1a.
On engin e
having hydraulic valve lifters,
run engine until lifters are completely filled
a. Replacement of Timing Chain
1.
Drain cooling system and remove radiator
core.
2. Remove fan belt and crankshaft balancer.
3. Remove timing gear cover after loosen-
ing two lower
crankcase
bolts on each side to
a void damage to gasket.
4. Check the slack in timing
chain.
Initial
slack in the timing chain when new allows
tA."
to
%"
outward movement under finger pressure
applied midway between points of contact with
sprockets. Permissible slack in a
worn
chain
can be as high as 1" outward
before
it is neces-
sary to replace the chain.
5.
If
chain requires replacement, turn crank-
shaft to align timing marks on sprockets with
timing marks on chain. Each sprocket has a
Figure 2-27-Timing
Chain
and Sprocket Marks
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