Valve Guide Reaming/Valve and Seat Grinding

1. Ream the valve guides for oversize valves if the clearance exceeds the specifications.

IMPORTANT: A valve stem that has excessive scoring or wear must be replaced. A valve guide that is worn and has excessive stem-to-guide clearance should be sleeved.





2. Measure the valve stem-to-guide clearance.

IMPORTANT: Follow the manufacturers instructions when using valve guide reamers, sleeves, and installers.





3. Ream the valve guide to obtain the proper specification.

IMPORTANT: Valves that are pitted must be refaced to the proper angle. Valve stems that show excessive wear, or valves that are warped must be replaced. Several different types of equipment are available for refacing valves and valve seats. Follow the manufacturers recommendations when performing these procedures.





4. Inspect the valves for excessive scoring.





5. Inspect the valve face. Replace the valve if the valve margin is not within specifications after grinding.
6. Reface pitted valves on a valve refacing machine to insure the correct relationship between the head and the stem.

IMPORTANT: Reconditioning the valve seats is very important. The seating of the valves must be perfect for the engine to deliver optimum power and performance. Clean the valve guides of all debris and dirt before grinding of the valve seat.

7. Recondition the valve seats after reaming the valve guide bores or installing the new valve guides.
8. The valve seats should be concentric to within 0.05 mm (0.031 inch) total indicator reading.
9. Measure valve stem installed height, with the valve stem oil seal and valve spring seat removed, after all reconditioning has been completed.
10. If the valve stem height is not within specifications install 0.25 mm (0.010 inch) rocker arm shims as necessary. If more than two shims are needed the cylinder head or valve must be replaced.