496
CID (8.1L)
SERVICE MANUAL NUMBER 30
Valve Seat Repair
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 important to ensure that heat in valve head will be properly dispersed.
Several different types of equipment are available for reseating valve seats. Equipment
manufacturer’s recommendations should be followed carefully to attain proper results.
a
76781
a - Seat Width
Regardless of type of equipment, 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.
Page 3A-34
INDEX
90-863161 SEPTEMBER 2000
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 496 CID |
| Model Year | 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(2 votes, average: 4 out of 4)
Marine readers have rated Mercury MerCruiser 496 CID 8.1L Gasoline Marine Engines Service Manual Number 30 4.0 out of 4.0 based on 2 product reviews. How many openings for crankcaseventilation is there on
Merc 496 HO ?
Great down load . it was all there an more