6-4 VALVES, VALVE SEATS, AND GUIDE (CONT)
exhaust valve and valve seat to 45° angle, and in-
take valve and valve seat to 30° angle. Lap with
fine lapping compound (Item 7, Appendix E) to
remove grinding marks. Surfaces of both valve
seats should be 3/64 to 1/16 inch (1.19 to 1.58 mm)
wide. If seat is wider, a narrowing stone or cutter
should be used. Valve margin must be greater than
1/64 inch (0.4 mm) after refacing. If either seat or
valve is badly burned, or margin is 1/64 inch (0.4
mm) or less, replace.
Apply antiseize compound (Appendix E, Item 1) to valve stems and guides
(5 and 6) before installing. Be sure no compound is on ends of valve stems
If flat end of reject gauge can be inserted into
guide (5) a distance of 5/16 inch (7.94 mm)
guide is worn and should be replaced.