MerCruiser 305 CID (5.0L) Service Manual page 205

SERVICE MANUAL NUMBER 24
Valve Grinding
Valves that are pitted must be refaced to the proper angle. Valve stems that show excessive
warp or wear, must be replaced. When a warped valve head 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. Heat will localize on this edge and lead to breakage, burning or pre-
ignition. If the edge of the valve head (valve margin) is less than 0.031 in. (0.79 mm) after
grinding, replace the valve.
Several different types of equipment are available for refacing valves. The manufacturer's
recommendation should be carefully followed to attain proper results.
Reassembly
1. Lubricate valve guides and valve stems with engine oil.
2. Install each valve in the port from which it was removed or to which it was fitted.
3. Install valve guide seal (intake valve only) over valve stem and push down until seated
4. Set valve spring (with damper installed) and shield in place.
5. Place cap on intake valve and/or rotator on exhaust valve.
Index
90-861327--1 OCTOBER 1999
b
Exhaust
a - .341 In. (8.16 mm)
b - 0.031 (0.79) Minimum
against head.
a
Intake
5.0l / 305 cid / 5.7l / 350 cid ENGINES
a
b
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