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20
Chapter l-General Engine
Overhaul,
In spection, and Repair
TooI-T52i
·
6085-AEE
(223 AND 272
]ECW·Y]
CUBIC INCH
ENGINES)
Tool-T56T-60B5 -A (272
]ECR]
302
AND 332
CUBIC
IN
CH
ENGINES)
Fig.
23-Reaming Valve
Guides-Typical
6543
(d) SELECT FITTING VALVES. Oversize valves with a
stem diameter
of 0.003, 0.015,
and 0.030 inch are avail-
able for service. Occasionally the 0.003 inch oversize
valve is
used
in production in one or more positions.
If the valve
stem
clearance is excessive and the
diameter of the valve stem
is
on the lower
limit
(as
determined
by
measuring the valve stem with a microm-
eter)
J
select a new valve with a stem diameter on the
upper limit. If in the
use
of standard valves the clear-
ance cannot be reduced to a satisfactory
limit,
ream
the valve guide (fig. 23) for the next
oversize
valve
stem.
Combination Ad;usling Tool
~::::.--.-
Fig.
24-Valve Lash
Ad;usrmenr-Typical
Table
2-Valve
Lash Specificarions
Engine
Preliminary
Final
( Cu.
In.)
(Cold)
(Hot)
INT.
EXH.
INT.
EXH.
223
0.019
0.019
0.019
0.019
272
0.018
0.Ql8
0.018
0.Ql8
302
0.007
0.023
0.009
0.021
332
0.007
0.023
0.009
0.021
d. Valve
Lash
Adjustment.
Reference is
made
in
the
procedures for a preliminary
(cold) valve
lash
.a
djustment to placing
number
1 piston
on
top dead center (TD.C.) at
the end of
the
compres-
sion
stroke.
Number 1 piston is on T.D.C. at the
end
of
the
compression
stroke
when
both valves are closed.
and
the
timing
mark
on
the crankshaft damper is
in
line with
the
timing pointer.
Step-type
feeler
gauges
("go"
and
"no go") can be
used to
obtain the
proper clearance (fig. 24).
Valve lash
is
adjusted by means of
the
set screw and
lock
nut located
on the push rod end of
the rocker
arm.
It
is very
important that
the
valve
lash of
all valves
be
held
as
close
as
possible to the correct specifications
(Table
2).
If the
valve lash is
set too
low,
rough
engine
idle
and
poor engine
performance can
result. If
the valve
lash is
excessive,
valve action
noise
will result,
and engine
performance will
be affected.
If the cylinder
head
or the
rocker mechanism has
been removed and
installed, it
will be
necessary
to make
a preliminary adjustment before
starting the
engine.
If
the valve lash adj ustment
is
made
for
the
purpose of
engine
tune-up,
omit step (a) and proceed
with
step (b)
under
the
procedure
for
the applicable engine.
(1) 6·CYLINDER
ENGINE.
Remove
the rocker arm
cover.
(a)
PRELIMINARY
ADJUSTMENT.
Make two
chalk
marks
on
the
crankshaft
damper. Space the
marks
approximately 120
0
apart
so
that
with
the timing
mark,
the
damper
is divided into
three
equal
parts (120
0
represents
1
/
3
of
the
distance around the damper
circumference) .
Rotate the crankshaft
until number
1
piston is near
T.D.C.
at
the
end
of
the
compression
stroke.
Adjust
the
intake
and
exhaust valve
lash for number
1
cylinder.
Repeat this procedure
for the remaining
sets of valves,
turning the
crankshaft
1/3
turn at a
time,
in
the
direction
of
rotation,
while
adjusting the
valves
in
the firing order
sequence
(1-5-3·6-2-4
).
(b)
FINAL
ADJUSTMENT.
Run
the engine
for
a
min-
imum of 30 minutes at
approximately 1200
r.p.m. in
order to stabilize
engine
temperatures.
With
the
engine
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