If your going to machine down some OS valve guides,

I'd make sure your hole is true and no metal was removed. If not, then you want to ream the hole, then machine to fit.

Steve- heat the heat slightly(250F) and cool the guide in a "chill box", the new guides won't be any problem.

Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E