V-8
ENGINE
6-49
i
w
Fig.
6-85
Testing
Leak-Down
Rate
4.
Invert
plunger with parts assembled thus far
and,
after rinsing lifter body,
Install
body over
spring
and plunger.
5. Place orifice
feed
plate In plunger.
6. Place lifter body on clean paper; rinse and in-
stall
push rod seat and retainer
ring.
7. After lifter has been assembled, place in lifter
box and close lid to preserve cleanliness.
TEST
VALVE
LIFTER
LEAK-DOWN
RATE
After
all lifters have been assembled, the leak-
down rate must be checked before they are installed
in
the engine. Valve lifter leak-down tester J
5790
(Fig.
6-85) is designed to
test
leak-down rate of
lifters
to determine whether or not they are within
specified limits. As with previous service operations
concerned with lifters, cleanliness is important. The
tester cup and ram should be thoroughly cleaned,
and
testing should be
done
in an
area
free of dust and
dirt.
The testing procedure is described in the
following steps:
1.
Fill
tester cup to approximately one inch from
top with special fluid which is available from your
lifter
tester dealer.
NOTE:
No
other
type
fluid
is
recommended.
2.
Swing weight arm up out of the way, raise
ram,
and position lifter into
boss
in center of
tester cup.
3.
Adjust ram (with weight arm clear of ram) so
that the pointer is positioned on the set line (marked
"S").
Tighten jam nut to maintain setting.
4. Operate lifter through
full
travel of plunger by
pumping weight arm to
fill
lifter with
test
fluid and
force out air.
(Lifter
must be completely submerged
at all times.) Continue pumping for several strokes
after definite resistance is detected.
5. Raise weight arm to allow plunger spring to
expand fully; lower arm
onto
ram and commence
turning
crank
slowly (1 revolution every 2 seconds).
Time
indicator travel from lower line (first line
above set line) to line marked .125 or 1/8", while
still
rotating cup with
crank
(Fig. 6-85).
Lifter
is
satisfactory if rate, is between 20 and 90 seconds.
A
doubtful lifter should be
tested
three or four
times. Disassemble, inspect, and re-test doubtful
lifters.
If leakdown
still
is not within specifications,
replace
lifter.
6. After each lifter is tested, replace in lifter box
to insure cleanliness.
Leave
lifters in box until ready
for
installation in cylinder block.
7. When all lifters have been tested, empty cup,
clean,
and place cover over tester to maintain its
cleanliness.
CYLINDER
HEAD
OR
GASKET-
REMOVE
AND
REPLACE
'
REMOVE
1. Remove intake manifold, push rod cover, and
rocker
arm cover.
2.
Loosen all rocker arm retaining nuts and move
rocker
arms off push rods.
3.
Remove push rods and place in a support stand
so they can be replaced in exactly the same position
from
which they were removed. See
GENERAL
IN-
FORMATION
ON
ENGINE
SERVICE.
4. Remove exhaust pipe to manifold attaching bolts.
5. On
Firebird
models, remove compressor attach-
ing
bolts, if equipped with
A/C,
and move compres-
sor
to one side when removing head.
6. Remove battery ground strap and engine ground
strap
on left head or engine ground strap and auto-
matic
transmission oil level indicator tube bracket
on right head.
7. Remove cylinder head bolts (dowel pins
will
hold
head in place) and remove head with exhaust
manifold
attached, using lifting hooks J 4266.
CAUTION:
Extreme
care
should
be
taken
when
handling
or
storing
cylinder
heads
as the
rocker
arm
studs
are
hardened
and may
crack
if
struck.
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