Pontiac FIREBIRD 1972 Service Manual page 579

V-8 ENGINE 6-67
5. Place orifice feed plate in plunger.
6. Place lifter body on clean paper; rinse and install
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. 6-110) is de-
signed 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, cleanli-
ness 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 w h i ~ h is available from your lifter
tester dealer.
NOTE: No other type fluid is recommended or
should be used.
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.
Fig. 6-1 10 Testing Leakdown Rate
4. Operate lifter through full travel of plunger by pump-
ing 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 .I25 or 1/8" while still rotating
cup with crank (Fig. 6-1 10).
Lifter is satisfactory if rate is between 20 and 90
seconds (455 H.O. lifter leak-down rate should be 12
to 60 seconds).
A doubtful lifter should be tested three or four times.
Disassemble, inspelct and re-test doubtful lifters. If
leak-down still is not within specifications, replace
lifter.
6. After each lifter is tested, replace in lifter box to
insure cleaniness. 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 cleaniness.
CYLINDER HEAD OR GASKET
REMOVE
1.
Drain cooling system, including block.
2. Remove intake manifold, push rod cover (all but 307
engine), and rocker arm cover.
3. Loosen all rocker arm retaining nuts and move
rocker arms off push rods.
4. 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.
5. On all but left head of 455 H.O., remove exhaust pipe
to manifold attaching bolts.
6. In order to' remove the left head of the 455 H.O., it
will be necessary to remove the exhaust manifold
attaching nuts and drop manifold. Remove inner
panel of carburetor heat stove from two center cylin-
der head bolts.
7. Remove battery ground cable and engine ground
strap or engine ground strap and automatic transmis-
sion oil level indicator tube bracket on head to be
removed.