MX-5 Miata Mazdaspeed L4-1.8L DOHC Turbo (2004)
Valve Seat: Service and Repair
Valve Seat Inspection/Repair
1. Measure the seat contact width. As necessary, resurface the valve seat using a 45° valve seat cutter and/or resurface the valve face.
2. Verify that the valve seating position is at the center of the valve face.
1) If the seating position is too high, correct the valve seat using a 70° cutter, and a 45° cutter.
2) If the seating position is too low, correct the valve seat using a 45° cutter.
3. Inspect the sinking of the valve seat. Measure the protruding length (dimension L) of the valve stem. Replace the cylinder head as necessary.
Standard dimension L
IN: 45.0 mm (1.772 inch)
EX: 45.0 mm (1.772 inch)
Maximum dimension L
IN: 45.6 mm (1.795 inch)
EX: 45.6 mm (1.795 inch)
