Grinding Valve Faces And Seats

Valve seat grinding tools and fixtures are available commercially. Grind and seat each valve in same port from which it was disassembled.

Valve face angle is 45° for both intake and exhaust valves, and valve refacing grinder must be adjusted exactly to this angle. It Is important to not remove any more metal than is necessary to clean up and true valve face. If grinding leaves the edge of valve very thin or sharp, install a new valve. A valve In this condition does not seat normally, will burn easily and may cause pre-ignition. There is also danger of cracking. Valves that do not clean up quickly are probably warped or too deeply pitted to be used.

Figure 3B-4. Lapping Valves

If end of valve stem shows uneven wear, true end of stem on a valve refacing grinder equipped with suitable attachment.

Standard intake and exhaust valves are made of different materials and must not be interchanged. Intake valves are marked "IN" on head; exhaust valves are marked "EX".

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