Valve Seat Inspection/Repair

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata, 2004 Mazda MX-5 Miata, and 2003 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

Measure the seat contact width. As necessary, resurface the valve seat using a 45 ° valve seat cutter and/or resurface the valve face.
Standard Width
1. 0.8-1.4 mm {0.032-0.055 in}
  
  Fig 1: Measuring Seat Contact Width
  Courtesy of MAZDA MOTORS CORP.
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.
  
  Fig 2: Centering Valve Seating Position
  Courtesy of MAZDA MOTORS CORP.
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
1. IN: 45.0 mm {1.772 in}
2. EX: 45.0 mm {1.772 in}
Maximum Dimension L
1. IN: 45.6 mm {1.795 in}
2. EX: 45.6 mm {1.795 in}