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Valve Tolerances?

Ken H.

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How much run-out is typically acceptable in a valve?


If I chuck my valves in my drill press and measure the run-out at the seat, on one intake I'm showing about 2 thousands out of round, on the other about 4. Some of this is the drill press, at the chuck it is about 0.25 of a thousand out of round, and the spinning valve seat is about 3" below that, but I'm wondering of these are damaged/with bent stem or not?


The exhaust each show less than 1 thousand out.

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You just flat can't use a drill press for this. Too much slop in the thing, and the three jaw drill press chuck pretty much makes it a by guess and by gosh thing.


Take it to either a machine shop, or better yet, an automotive machine shop and have them both check the valves and re-cut the seats while they are at it. The fixture used to do this comes equipped with some pretty precise components. I would say 0.004 out is certainly too much.

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