Valve and Seat Reconditioning Procedure
WARNING: This page is about a different variant/trim than selected.
- If the valve seat width, roundness or concentricity is beyond specifications, you must grind the seats in order to ensure proper heat dissipation and prevent the build up of carbon on the seats.
- It is necessary to reface the valve if seat reconditioning is required unless a new valve is used.
- Grind the valve seating surface (a) to the proper angle specification (2) listed in Engine Mechanical Specifications (LEA, or LUK) .
- Grind the valve relief surface to the proper angle specification (1) listed in Engine Mechanical Specifications (LEA, or LUK) , to correctly position the valve seating surface (a) to the valve.
- Grind the valve undercut surface to the proper angle specification (3) listed in Engine Mechanical Specifications (LEA, or LUK) , to narrow the valve seating surface width (a) to the specifications listed in Engine Mechanical Specifications (LEA, or LUK) .
- Replace the intake valve if it is out of specification. Refer to Engine Mechanical Specifications (LEA, or LUK) .
- If the original exhaust valve is being used, grind the valve to the specifications listed in Engine Mechanical Specifications (LEA, or LUK) . Measure the valve head O.D. and chamfer again after grinding using the Valve Head O.D. and Chamfer Measurement Procedure. Replace the exhaust valve if it is out of specification. New valves do not require grinding.
- When grinding the valves and seats, grind off as little material as possible. Cutting valve seat results in lowering the valve spring pressure.
- Install the valve in the cylinder head.
- If you are using refaced exhaust valves, lap the valves into the seats with a fine grinding compound. The refacing and reseating operations should leave the refinished surfaces smooth and true so that minimal lapping is required. Excessive lapping will groove the valve face and prevent a good seat when hot.
- Be sure to clean any remaining lapping compound from the valve and seat with solvent and compressed air prior to final assembly.
- After obtaining the proper valve seat width in the cylinder head, you must re-measure the valve stem height using the Valve Stem Height Measurement Procedure.
- If the valve stem height is acceptable, test the seats for concentricity using the Valve-to-Seat Concentricity Measurement Procedure.
NOTE:
NOTE:
Do not grind or condition the intake valve. If the intake valve seat has been reconditioned, replace the corresponding intake valve.