Valve Seat: Service and Repair

VALVE SEAT INSPECTION/REPAIR




1. Measure the contact width of the valve face and the valve seat using the valve lapping compound (red lead).

Valve seat standard contact width 0.8-1.4 mm {0.04-0.05 in}




- If not within the specification, resurface the valve seat using the 45° valve seat cutter or resurface the valve face, or the both.

2. Verify that the valve seating position is at the center of the valve face.
- If the seating position is too high, correct the valve seat using a 70° (IN) 70° (EX) valve seat cutter, and a 45° valve seat cutter.
- If the seating position is too low, correct the valve seat using a 35° (IN) 30° (EX) valve seat cutter, and a 45° valve seat cutter.

Valve seat angle 45°




3. Check the valve seat for sinking. Measure the protruding length (dimension L) of the valve stem using a valve of standard length.
- If it exceeds the specification, replace the cylinder head.

Valve seat standard sinkage amount (Dimension L) 39.25 mm {1.545 in}