Valve Seat: Service and Repair

VALVE SEAT INSERT REPLACEMENT





1. Cut away the inner face of the valve seat to reduce the wall thickness, then remove.





2. Adjust the press fit diameter of the valve seat on the cylinder head side so that it matches the diameter of the oversize valve seat.





Valve seat insert oversizes

3. Heat the cylinder head to about 250°C (480°F) and press in an oversize seat insert and fit to the insert bore in the cylinder head (at normal temperature).





4. Treat the valve seat as shown in the illustration.
5. Use the lapping compound, and lap the valve.

Valve seat contact width:
Standard value:
Intake: 0.9 - 1.3 mm (0.035 - 0.05 inch)
Exhaust: 0.9 - 1.3 mm (0.035 - 0.051 inch)