Specifications

1-8
GROUP 1- ENGINES AND EXHAUST SYSTEMS
ENGINE TESTS AND ADJUSTMENTS
PRELIMINARY (COLD) VALVE
LASH—MECHANICAL VALVE
LIFTERS
If the valve rocker arm shaft
assembly has been removed and in-
stalled, it will be necessary to make
a preliminary (cold) valve lash ad-
justment before starting the engine.
If the adjustment is made for an
engine tune-up, follow the final ad-
justment procedure.
The cylinders are numbered from
front to rear—right bank, 1-2-3-4;
left bank, 5-6-7-8.
On the 292 V-8, the valves are
arranged from front to rear on both
banks, E-I-I-E-E-I-I-E.
On the 390 V-8 engines, the valves
are arranged from front to rear on
both banks, E-I-E-I-I-E-I-E.
1. Turn all the valve adjusting
screws until interference is noted.
Check the torque required to turn
the screw further. If the torque re-
quired to turn a screw is less than
3 ft-lbs (36 in-lbs), try a new self-
locking adjusting screw. If this is still
unsatisfactory, replace the rocker arm
and adjusting screws.
2. Make three chalk marks on
the crankshaft damper (Fig. 1).
Space the marks approximately 90°
apart so that with the timing mark,
the damper is divided into four
equal parts (90° represents 1/4 of
the distance around the damper cir-
cumference). Set the intake and ex-
haust valve lash to specifications.
STEP 1 —SET NO. 1 PISTON ON T. D. C.
AT END OF COMPRESSION STROKE. —ADJUST
NO. 1, 4, 5 EXHAUST & NO. 1, 2, 7 INTAKE.
STEP 2 —ADJUST NO. 6 & 8 EXHAUST
I & NO. 4 & 5 INTAKE.
STEP 3 —ADJUST NO. 2, 3, 7 EXHAUST
& NO. 3, 6, 8 INTAKE. A12O3-C
FIG. 1-V-8 Preliminary Valve
Lash Adjustment
3. Rotate the crankshaft until
No. 1 piston is near TDC at the end
of the compression stroke. Adjust the
following valves:
No. 1 Exhaust No. 2 Intake
No. 4 Exhaust (292 V-8)
No. 5 Exhaust No. 7 Intake
No. 1 Intake No. 8 Intake
(390 V-8)
4. Rotate the crankshaft 180° or
Vi turn in the direction shown in Fig.
1 (this puts No. 4 piston on TDC).
Adjust the following valves:
No. 2 Exhaust No. 8 Exhaust
(390 V-8) No. 4 Intake
No. 6 Exhaust No. 5 Intake
(292 V-8)
5. Rotate the crankshaft another
¥4 turn in the same direction (this
puts No. 3 piston on TDC). Adjust
the following valves:
No. 2 Exhaust No. 2 Intake
(292 V-8) (390 V-8)
No. 3 Exhaust No. 3 Intake
No. 7 Exhaust No. 6 Intake
No. 8 Exhaust No. 8 Intake
(390 V-8) (292 V-8)
VALVE LASH (HOT) —
MECHANICAL VALVE LIFTERS
It is very important that the valve
lash be held to the correct specifica-
tions because:
If the lash is set too close, the
valve will open too early and close
too late, resulting in rough engine
idle. Burning and warping of the
valves will occur also because the
valves cannot make firm contact with
the seats long enough to cool
properly. If the lash is excessive, it
will cause the valve to open too late
and close too early causing valve
bounce. In addition, damage to the
camshaft lobe is likely because the
tappet foot will not follow the pattern
of the camshaft lobe causing a shock
contact between these two parts.
1. Be sure the engine is at normal
operating temperature before at-
tempting to set the valve lash.
2. With the engine idling, set the
valve lash (Fig. 2) using a step-
type feeler gauge only ("go" and "no
go"). The final (hot) intake and
exhaust valve lash settings are listed
in the Specification Section.
For example, to obtain the correct
setting if the valve lash is 0.019 inch,
use a step-type feeler gauge of 0.018
Step - Type Feeler Gauge Al 466-A
FIG. 2-Valve Lash Adjustment
—Mechanical Valve Lifters
inch ("go") and 0.020 inch ("no go").
The "go" step should enter, and the
"no go" step should not enter. The
resultant setting will be to the re-
quired setting (0.019 inch).
VALVE CLEARANCE-
HYDRAULIC VALVE LIFTERS
A 0.060-inch shorter push rod
(color coded white) or a 0.060-inch
longer push rod (color coded yellow)
are available for service to provide a
means of compensating for dimen-
sional changes in the valve mecha-
nism. Valve stem to valve rocker
arm clearance should be to the
specified clearance with the hydraulic
lifter completely collapsed. Repeated
valve reconditioning operations
(valve and/or valve seat refacing)
will decrease the clearance to the
point that if not compensated for,
the hydraulic valve lifter will cease
to function. To determine whether a
shorter or a longer push rod is neces-
sary, make the following check:
1. Position the crankshaft as
outlined in steps 2 and 3. Position
the hydraulic lifter compressor tool
on the rocker arm and slowly apply
pressure to bleed down the hydrau-
lic lifter until the plunger is com-
pletely bottomed (Fig. 3). Hold the
lifter in the fully collapsed position
and insert the clearance gauge (Fig.
3) between the valve stem and the
rocker arm of the valve being
checked. If the first step of the
gauge enters, the old push rod may
be used. If the first step will not
enter, replace the standard push rod
with a shorter service push rod. If
the second step of the gauge enters,
the operating range of the lifter is
excessive which indicates that the
incorrect push rod has been in-