Valve Adjustment; Valve Stem Seal And Valve Spring Replacement - GMC G Service Manual

R Install or Connect
1. Pushrod. Make sure the pushrod seats properly in the
hydraulic lifter.
2. Rocker arm with ball.
I"?! Important
• When new rocker arms and/or balls are
installed, coat their bearing surfaces with
"Molykote" or equivalent.
3. Rocker arm nut.
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Adjust
• Valves as outlined later.
4. Rocker arm cover, as outlined previously.

VALVE ADJUSTMENT

1. Remove the rocker arm cover as outlined previously.
2. Crank the engine until the mark on the vibration
damper lines up with the "0" mark on the timing tab
and the engine is in the number one firing position.
This may be determined by placing fingers on the
number one valve as the mark on the damper comes
near the "0" mark on the timing tab. If the rocker arms
are not moving, the engine is in the number one firing
position. If the rocker arms move as the mark comes
up to the timing tab, the engine is in the number six
firing position and should be turned over one more
time to reach the number one position.
3. With the engine in the number one firing position as
determined above, the following valves may be
adjusted:
• Exhaust: 1, 3, 4, 8
• Intake: 1, 2, 5, 7
(Even numbered cylinders are in the right bank; odd
numbered cylinders are in the left bank, when viewed
from the rear of the engine.)
4. 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 3).
When the play has been removed, turn the adjusting
nut in three quarters (3/4) additional turn (to center
the lifter plunger).
5. Crank the engine one revolution until the timing tab
"0" mark and vibration damper mark are again in
alignment. This is the number six firing position; the
following valves may be adjusted:
• Exhaust: 2, 5, 6, 7
• Intake: 3, 4, 6, 8
6. Install the rocker arm cover as outlined previously.
7.4 LITER V8 6A5-5
VALVE STEM SEAL AND VALVE
SPRING REPLACEMENT
M Remove or Disconnect (Figures 4 and 5)
Tools Required:
J 23590 Air Adapter
J 5892-B Spring Compressor
1. Rocker arm cover, as outlined previously.
2. Rocker arms, as outlined previously.
3. Spark plugs.
4. Valve keepers.
• Install J 23590 into the spark plug hole.
• Apply compressed air to hold the valves in
place.
• Install a rocker arm nut (figure 5).
• Use J 5892-B to compress the valve spring (fig­
ure 5).
• Remove the valve keepers.
• Carefully release the spring tension. Remove
J 5892-B.
5. Cap (26) and spring with damper (29).
6. Seal (33).