SERVICE MANUAL NUMBER 23
454 CID (7.4L) / 502 CID (8.2L)
Regardless of type of equipment, however, it is essential that valve guide bores be free from
carbon or dirt to achieve proper centering of pilot in valve guide, ensuring concentricity.
72568
Measuring Valve Seat Concentricity
Valve Grinding
Valves that are pitted must be refaced to the proper angle. Valve stems that show excessive
wear or valves that are warped excessively must be replaced. When a valve head that is
warped excessively 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 grinding, replace the valve.
Several different types of equipment are available for refacing valves. The recommendation
of the manufacturer of the equipment being used should be carefully followed to attain prop-
er results.
a
a
b
b
50695
Exhaust
Intake
a - 0.372 In. (9.45 mm)
b - 1/32 [.031] In. (0.79 mm) Min.
Index
90-861326--1 MARCH 1999
Page 3A-45
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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