46. Valve Guide Reaming, and Valve and Seat Grinding

Valve Guide Reaming, and Valve and Seat Grinding

Valve Guide Reaming Procedure




1. Ream the valve guide as necessary to achieve proper valve stem-to-guide clearance.

1. Ream the valve guide oversize to accept a valve guide sleeve.
2. Insert the valve guide sleeve into the guide bore.
3. Ream the sleeve to achieve proper valve stem-to-guide clearance.

2. Always recondition the valve and valve seat after reaming the valve guide bores or installing new valves.
3. Replace the cylinder head if the valve guide cannot be repaired.

Valve Reconditioning Procedure

1. Replace the valve if the following conditions exist:

* The valve stem has excessive wear
* The valve stem is warped
* The valve head is warped

Important: Several different types of equipment are available for reconditioning valves. Use the manufacturers recommendations of equipment to attain the proper results.


2. Reface severely pitted valves on a valve refacing machine in order to insure the correct relationship between the head and the stem.




3. Replace the valve if the edge of the head is less than 0.79 mm (0.031 in) thick after grinding.

Valve Seat Reconditioning Procedure

Important: Several different types of equipment are available for reconditioning valve seats. Use the manufacturers recommendations of equipment to attain the proper results.


Important: Always recondition the valve and valve seat after reaming the valve guide bores or installing new valves.


1. Recondition the valve seats.
2. The valves must seat perfectly for the engine to deliver optimum power and performance.
3. Ensure that the valve seat and valve are not shrouded after valve seat reconditioning. Adequate flow past the valve seat and valve is essential for cooling the valve head and valve seat area.




4. Correct contact (1) between each valve and its seat in the cylinder head is also essential to ensure that the heat in the valve head is properly carried away.

Important: 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.


5. The valve seats should be concentric to within 0.05 mm (0.002 in) total indicator runout.