Quote:
Originally Posted by Larry Hill
You have used up all of the tolerance. If the valve is out of concentricity the valve will hit the high side of the seat on the side with the greater run out. The spring will cause the valve to conform, bend, to the seat. How many cycles will it take for metal fatigue to appear?
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Guide wear too.
That's not to say that if the valve pounds into the seat you won't have the same issue.
For me, it's a simple question: Why start with poor run-out when you don't have to?
Is it the valve or the valve-grinder? Quality valves with good margins tend to eliminate a lot of guesswork. Same goes for quality grinders that are well maintained and have the right stone and good, clean oil.