340 1.88 intake valve coloration normal?

[dibbons]

After cleaning up the intake valves in a used 340, found a pretty rainbow hue to them. They don't appear to be bent, warped, or melted. They still have plenty of margin left. Is this color unusual for a used valve? Thank you.

 

[66fs]

yes

 

[GeorgeH]

Blued, toss it

 

[66fs]

If the stems are within spec, and .0005 or less taper, I grind the face. If it cleans up with minimum grinding, I'll back cut and run them. OEM HP stems are typically .0005 smaller in diameter.

 

[moper]

I don't see a problem with it provided it's still in good shape aside from the coloring.