Valve Adjustment - GMC G Service Manual

0 Adjust
• Valves. Refer to "Valve Adjustment" in this
section.
4. Rocker arm cover. Refer to "Rocker Arm Cover
Replacement" in this section.

VALVE ADJUSTMENT

1. Remove the rocker arm cover. Refer to "Rocker Arm
Cover Replacement" in this section.
2. Adjust the valves when the lifter is on the base circle
of the camshaft lobe as follows:
a. Mark the distributor housing with chalk at #1
and #6 plug wire positions. Remove the distrib­
utor cap and set aside.
b. Crank the engine until the distributor rotor
points to #1 cylinder position. The following
valves can be adjusted with the engine in the
#1 firing position:
#1 cylinder — Exhaust and Intake
#2 cylinder — Intake
#3 cylinder — Exhaust
#4 cylinder — Intake
#5 cylinder — Exhaust
c. Back out the adjusting nut until lash is felt at the
pushrod, then turn in the adjusting nut until all
lash is removed. This can be determined by
rotating the pushrod while turning the adjusting
nut (figure 4). When play has been removed,
turn the adjusting nut in one full additional turn
(to center the lifter plunger).
d. Crank the engine until the distributor rotor
points to #6 position. The following valves can
be adjusted with the engine in #6 firing position:
#2 cylinder — Exhaust
#3 cylinder — Intake
#4 cylinder — Exhaust
#5 cylinder — Intake
#6 cylinder — Intake and Exhaust
3. Install the distributor cap.
4. Install the rocker arm cover. Refer to "Rocker Arm
Cover Replacement" in this section.
4.8 LITER L6 6A7-5
VALVE STEM SEAL AND VALVE
SPRING REPLACEMENT
M Remove or Disconnect (Figures 5 and 6)
Tools Required:
J 23590 Air Adapter
J 5892-B Spring Compressor
1. Rocker arm cover. Refer to "Rocker Arm Cover
Replacement" in this section.
2. Rocker arms. Refer to "Rocker Arm and Pushrod
Replacement" in this section.
3. Spark plugs.
4. Valve keepers (20).
• Install J 23590 into the spark plug hole.
• Apply compressed air to hold the valves in
place.
• Install a rocker arm nut (figure 6).
• Use J 5892-B to compress the valve spring (fig­
ure 6).
• Remove the valve keepers.
• Carefully release the spring tension. Remove
J 5892-B.
5. Rotator (21), shield (22) and spring (26) with damper
(25).
6. O-ring seal (23).
7. Seal (24) (intake valve only).