Valve Seat Resurfacing

CAUTION: A valve seat not producing a uniform contact with its valve or showing seating contact that is off the specified width must be repaired by regrinding finish or by lapping. The valve seat for both the intake and exhaust valves are machined to two different angles. The seat contact surface is cut to a 45 degree angle and the area above the contact surface (closest to the combustion chamber) is cut to a 15 degree angle.

1. Using a 45 degree valve seat cutter, descale and clean up the seat with one or two turns.

CAUTION: Cut only the minimum amount necessary from the seat to prevent possibility of valve stem becoming too close to camshaft lobe.

2. Inspect seat contact width. Refer to Seating Contact Width. If seat is pitted or burned additional seat conditioning with a 45 degree valve seat cutter is required.
3. If contact area is too wide, use a 15 degree valve seat cutter to narrow. If contact area is too narrow, use the 45 degree valve seat cutter to widen.
4. After desired seat width is achieved, lap valve on seat in two steps, first with a course-size lapping compound applied to its face and secondly with a fine-size compound, each time using a valve lapper.