Valve Tolerances?

[Ken H.]

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.

[ShovelStrokeEd]

Ken,

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.