GM Service Manual Online
For 1990-2009 cars only

    Object Number: 663566  Size: SH
  1. Remove the carbon from the valve guide and valve seat surface.
  2. Resurface the valve face to 45 degrees. If valve margin falls below specifications after resurfacing then discard valve.
  3. Use a suitable tool to bring the valve contact width to the standard value. The valve seat angle is 45 degrees.

  4. Object Number: 663569  Size: SH
  5. Apply valve lapping compound to the valve seat surface.
  6. Insert the valve into the cylinder head.
  7. Turn the valve back and forth in its seat to lap the valve face to the valve seat.