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 in).
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 in).
Exhaust: 5.965-5.980 mm (0.2348-0.2354 in).
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 in).
Exhaust: 0.030-0.065 mm (0.0012-0.0026 in).
Maximum oil clearance:
Intake: 0.080 mm (0.0031 in).
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 in).
Exhaust: 96.900 mm (3.8150 in).
Minimum overall length:
Intake: 94.550 mm (3.7224 in).
Exhaust: 96.400 mm (3.7953 in).
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 in).
Minimum margin thickness: 0.500 mm (0.0200 in).
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 in).
5. If not, replace or grind the valve.