Chevrolet 1991 Light Duty Truck Repair Manual page 474

6A5-22 V8 ENGINES
oversize studs; J 6036 for 0.013-inch oversize
studs (figure 42).
3. Coat lower end (press-fit area) of stud with hypoid
axle lubricant. Drive the stud into place with a
hammer and J 6880. Stud is installed to proper
depth when the tool bottoms on the cylinder head
(figure 43).
ASSEMBLY (5.0L AND 5.7L ENGINES)
l 4 l Assemble (Figures 38, 40, and 44)
Tools Required:
J 8062 Valve Spring Compressor
J 23738-A Valve Seal Leak Detector
1. Valves (258 and 259).
• Lubricate the valve stems with engine oil.
• Insert the valves into the proper ports.
2 Seals (257). Install the seals over the valve stems
and seat them against the head.
3. Springs with dampers (256).
4. Shields (255).
5. Caps (253) (intake valves only).
6. Rotators (254) (exhaust valves only).
Engines)
A
# p M n . T , . | M T , .
L- v j ' r J , , l,L
C _ _______ 1 ............ ..... ............
A. Grind out this portion.
Figure 45—Cutaway Scale
t i
i
B5248
(7.4L Engine)
7. O-ring seals (252) and valve keepers (251).
• Compress the valve spring, using J 8062 (fig­
ure 40). Compress the spring enough so the
lower valve stem groove can be clearly seen.
• Push a new O-ring seal onto the valve stem.
The seal is to be installed on the stem's lower
groove. Make sure the seal is flat and not twist­
ed.
• Apply a small amount of grease to the area of
the upper valve stem groove. Assemble the two
valve keepers using the grease to hold the keys
in place. Make sure the keepers seat properly
in the groove.
• Release the compressor tool. Make sure the
valve keepers stay in place.
• Repeat the preceding steps on the remaining
valves.
• Check each seal, using J 23738-A (figure
Place the adapter cup over the shield. Operate
the vacuum pump. Observe the vacuum pump
gage. No air should be able to leak past the
seal. If the seal will not hold a vacuum, it may
have been damaged or improperly installed.
3 j| Measure (Figures 45 and 46)
Valve spring installed height of each valve spring
as follows:
1. Use a narrow, thin scale. A cutaway scale (fig­
ure 45) may be helpful.
2. Measure from the valve shim or spring seat to
the top of the shield (255) (figure 46).
3. If this measurement exceeds the figure given in
"Specifications,'' install valve spring seat shims
of sufficient thickness (between the spring
cylinder head) to give the desired measure­
ment. NEVER shim the spring so
installed height under the specified figure.
44).
and
to give
as an