Valve and Seat Inspection

1. Measure the radial runout of the valve head using V-blocks and a dial indicator. If the runout exceeds specifications, replace the valve.
Maximum Valve Head Radial Runout 0.08 mm (0.003 inch)





2. Measure the valve margin (1). If the margin is less than the minimum, replace the valve.
Standard Intake Valve Margin: 1.0 mm (0.039 inch)
Minimum Intake Valve Margin: 0.6 mm (0.024 inch)
Standard Exhaust Valve Margin: 1.2 mm (0.047 inch)
Minimum Exhaust Valve Margin: 0.7 mm (0.028 inch)
3. Use Prussian blue to create a valve face-to-valve seat contact pattern (2) on the valve face. The contact pattern should be uniform around the diameter of the valve, in the middle of the valve face and of the correct width.
Valve Face-to-Valve Seat Contact Pattern Width: 1.1-1.3 mm (0.043-0.0512 inch) for both intake and exhaust valves.





4. Measure the valve contact pattern by performing the following:
4.1. Apply a light coating of Prussian blue to the entire valve face. Seat the valve but do not rotate it. The Prussian blue traces transferred to the valve seat are an indication of concentricity of the valve seat.
4.2. Clean all traces of Prussian blue.
4.3. Apply a light coating of Prussian blue to the valve seat and repeat the check. The traces of Prussian blue transferred to the valve face indicates valve face concentricity.
5. Recondition the valve seat and/or replace the valves as necessary.