3A - 20 - ENGINES
90-816462 2-695
Valve Seats
Valve seat reconditioning is very important, since
seating of valves must be perfect for engine to deliver
maximum power and performance.
Another important factor is valve head cooling. Good
contact between each valve and its seat in head is im-
portant to ensure that heat in valve head will be prop-
erly dispersed.
Several different types of equipment are available for
reseating valve seats. Equipment manufacturer’s
recommendations should be followed carefully to at-
tain proper results.
Regardless of type of equipment, however, it is es-
sential that valve guide bores be free from carbon or
dirt to achieve proper centering of pilot in valve guide,
ensuring concentricity.
72338
a - Check Valve Seat Concentricity
Valves that are pitted must be refaced to the proper
angle. Valve stems which show excessive wear, or
valves that are warped excessively, must be re-
placed. When a valve head which is warped exces-
sively is refaced, a knife edge will be ground on part
or all of the valve head, due to the amount of metal
that must be removed to completely reface. Knife
edges lead to breakage, burning, or pre-ignition due
to heat localizing on this knife edge. If the edge of the
valve head is less than 1/32 in. (0.8 mm) after grind-
ing, replace the valve.
Several different types of equipment are available for
refacing valves. The recommendation of the man-
ufacturer of the equipment being used should be
carefully followed to attain proper results.
50695
EXHAUST
INTAKE
b
a
c
d
Exhaust
a - .372 In. (9.45 mm)
b - 1/32 [.031] In. (0.79 mm) Min.
Intake
c - .341 In. (8.16 mm)
d - 1/32 [.031] In. (0.79 mm) Min.
Reassembly
1. Lubricate valve guides and valve stems with en-
gine oil.
2. Install each valve in the port from which it was re-
moved or to which it was fitted.
3. Install valve guide seal (intake valve only) over
valve stem and push down until seated against
head.
4. Set valve spring (with damper installed) and cap
in place.
5. Place retainer on intake valve and/or rotator on
exhaust valve.
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Страница 2: ...90 816462 2 695 0 ...
Страница 7: ...1 A IMPORTANT INFORMATION GENERAL INFORMATION 72000 ...
Страница 15: ...1 B 50617 IMPORTANT INFORMATION MAINTENANCE ...
Страница 36: ...1 C IMPORTANT INFORMATION TROUBLESHOOTING ...
Страница 74: ...2 A 50633 REMOVAL AND INSTALLATION 4 CYL ALPHA ONE DRIVE ...
Страница 88: ...3 A 26790 ENGINE 181 CID 3 0L 4 CYLINDER GM ENGINE ...
Страница 137: ...4 A 72079 ELECTRICAL SYSTEMS STARTING SYSTEM ...
Страница 170: ...4 B 71855 ELECTRICAL SYSTEMS IGNITION SYSTEM ...
Страница 197: ...ELECTRICAL SYSTEMS CHARGING SYSTEM 4 C 72078 ...
Страница 237: ...4 D 72747 ELECTRICAL SYSTEMS INSTRUMENTATION ...
Страница 250: ...4 E 72938 ELECTRICAL SYSTEMS WIRING DIAGRAMS ...
Страница 264: ...5 A FUEL SYSTEM FUEL PUMP ...
Страница 271: ...5 B 72681 FUEL SYSTEM MERCARB 2 BARREL CARBURETOR ...
Страница 300: ...6 A 50628 COOLING SYSTEM SEAWATER COOLED MODELS ...
Страница 309: ...6 B 73665 COOLING SYSTEM CLOSED COOLING MODELS ...
Страница 325: ...C 6 EXHAUST SYSTEM MANIFOLD ...
Страница 331: ...7 A 71317 POWER STEERING PUMP ...