Tools Required

1. Use a caliper gage and measure the inside diameter of the valve guide bushing.

Standard Valve Guide Bushing Inside Diameter
5.485-5.510 mm (0.2159-0.2169 in)




2. Use a micrometer and measure the outside diameter of the valve stem.

Standard Intake Valve Stem Diameter
5.465-5.480 mm (0.2152-0.2157 in)

Standard Exhaust Valve Stem Diameter
5.440-5.455 mm (0.2142-0.2148 in)

3. To obtain the valve guide bushing oil clearance, subtract the valve stem outside diameter measurement from the valve guide bushing inside diameter measurement.

Standard Intake Valve Oil Clearance
0.005-0.045 mm (0.0002-0.0018 in)

Standard Exhaust Valve Oil Clearance
0.030-0.070 mm (0.0012-0.0027 in)

Maximum Intake Valve Oil Clearance
0.07 mm (0.0027 in)

Maximum Exhaust Valve Oil Clearance
0.09 mm (0.0035 in)

4. If the clearance is greater than the maximum specified, replace the valve and the valve guide bushing.



5. Use aJ 37968 and a hammer and tap the valve guide bushing out of the cylinder head.



6. Use aJ 37968 and a hammer and tap the new valve guide bushing into the cylinder head.
7. Install the valve guide bushing to the specified protrusion height of 11.5 mm (0.45 in).



8. Use a J 37971 and ream the valve guide bushing to obtain the standard specified clearance between the valve guide bushing and valve stem.

Standard Intake Valve Oil Clearance
0.005-0.045 mm (0.0002-0.0018 in)

Standard Exhaust Valve Oil Clearance
0.030-0.070 mm (0.0012-0.0027 in)

9. Reconditioning the valve seats is very important.
10. Recondition valve seat after reaming the 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.

11. Inspect the 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 be 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.
12. The valves must seat perfectly for the engine to deliver optimum power and performance.
13. 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.
14. 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 in) total indicator reading.

15. Replace any valve that is not in serviceable condition.