Valve: Testing and Inspection

STEM TO GUIDE OIL CLEARANCE
1. Clean valve guide bushings. Using a valve guide bushing brush and solvent, clean all the guide bushings.





2. Using a gasket scraper, chip off any carbon from the valve head.
3. Using a wire brush, thoroughly clean the valve.





4. Using a caliper gauge, measure the inside diameter of the guide bushing.
Valve guide bushing standard diameter: 6.010-6.030 mm (0.2366-0.2374 inch).





5. Using a micrometer, measure the diameter of the valve stem.
Valve stem standard diameter:
Intake: 5.970-5.985 mm (0.2350-0.2356 inch).
Exhaust: 5.965-5.980 mm (0.2348-0.2354 inch).
6. Subtract the valve stem diameter measurement from the guide bushing inside diameter measurement.
Standard oil clearance:
Intake: 0.025-0.060 mm (0.0010-0.0024 inch).
Exhaust: 0.030-0.065 mm (0.0012-0.0026 inch).
Maximum oil clearance:
Intake: 0.080 mm (0.0031 inch).
Exhaust: 0.100 mm (0.0039 inch.).
7. If the clearance is greater than maximum, replace the valve and/or the guide bushing.





OVERALL LENGTH
Check the valve overall length.
Standard overall length:
Intake: 95.050 mm (3.7421 inch).
Exhaust: 96.900 mm (3.8150 inch).
Minimum overall length:
Intake: 94.550 mm (3.7224 inch).
Exhaust: 96.400 mm (3.7953 inch).
If the overall length is less than minimum, replace the valve.

STEM TIP WEAR
Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, resurface the tip with a grinder or replace the valve.





MARGIN
Check the valve head margin thickness.
Standard margin thickness: 1.000 mm (0.0390 inch).
Minimum margin thickness: 0.500 mm (0.0200 inch).
If the margin thickness is less than minimum, replace the valve.

VALVE SEAT POSITION AND WIDTH
1. Apply a light coat of Prussian blue (or white lead) to the valve face.
2. Lightly press the valve against the seat. Do not rotate valve.





3. If blue appears 360° around the face, the valve is concentric.
4. Check that the seat contact is in the middle of the valve face with the following width: 1.000-1.400 mm (0.0390-0.0550 inch).
5. If not, replace or grind the valve.