F510 & F525 Cylinder Head and Valves – RECONDITION VALVE SEATS
1. Inspect valve seats for damage. If seats are loose, warped or distorted beyond reconditioning, replace cylinder head. Pitted or worn seats can be refaced using NEW 128—30 ̊ x 45 ̊ Cutter Head and NEW 100-7.0—7 mm Pilot from JDM52A Valve Seat Service Set.
2. To recondition valve seat, cut at 45 ̊ angle (B) to clean up seat. Cut narrowing angle (E) at 30 ̊. Finish cut
at 45 ̊ (B) to establish seating surface width (A).
3. Cut valve seating surface (A) as close as possible to specifications.
4. Lap valves to seats after refacing. (See Lap Valves in this group.)
Seating Surface . . . . . . .1.10—1.46 mm (0.043—0.057 in.)
Seat Angle . . . . . 45 ̊
Face Angle . . . . . 45 ̊
Margin . . . . . . .. . . . . . . 0.60 mm (0.020 in.)
Narrowing Angle . . . 30 ̊
5. Center valve seat on the valve face:
(A) correct position.
(B) incorrect positions.
6. Check seat for good contact using Prussion Blue Compound.