Valve Guide Reaming/Valve and Seat Grinding

- TOOLS REQUIRED
- J-42096 Valve Guide Reamer.





1. Valve guides may be hand reamed for oversize valves if clearance exceeds the specifications using J-42096.
2. Service valves are available in standard and 0.075 mm oversize.
3. Hand ream valve guide bores for oversize valves as necessary. Reconditioning valve seats is very important.
4. Recondition valve seat after reaming valve guide bores.

IMPORTANT: Because the valve guide serves to support and center the valve grinder, it is essential that the valve guide is cleaned properly. If the valve guide requires reaming, this must be done first.

5. Inspect valve seats for excessive wear and burned spots. Valve seats may be reconditioned by grinding. If grinding results in the new seat being too wide it may he narrowed by using a 20 degree or 70 degree stone. The 20 degree stone will lower the seat and the 70 degree stone will raise the seat.
- The valves must seat perfectly for the engine to deliver optimum power and performance.
- Cooling the valve heads is another important factor. Good contact between each valve and its seat in the cylinder head is necessary to insure that the heat in the valve head is properly carried away.
- Regardless of what type of equipment is used, it is essential that the valve guide bores are free from carbon or dirt to ensure the proper centering of the pilot in the guide.
The valve seats should be concentric to within 0.05 mm (0.031 inch) total indicator reading.
6. Do not attempt to reface valves from the twin cam engine.
7. Replace any valve that is not within specification.