No Bronze Guides, Any Reason?

RustyRatRod said

What OldManMopar is referring to is very similar to sizing an intermediate shaft bushing with the special tool. Although it's not a ball, it does have round sides and as it's forced through the bushing, it resizes it. A little different, but same principle.

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As previously mentioned, when talking about valve guides it’s called “broaching”, and the tool is a “ball broach”.

With regards to guide liners, it “squeezes” the guide into the guide bore. It doesn’t actually remove any material.

If you trim the excess off the end of the liner so it’s flush with the guide boss before broaching, you’ll see it gets a little longer with each progressively larger broach.

I like to broach within a thou of the desired finished size, then I hone it the rest of the way.

My guess is if the OP has the guides measured with a proper guide bore gauge, the ex guides with be bellmouthed at the bottom.

With 3/8” stems in a street/strip application, I’d shoot for running them at about .0017”-.0018” clearance(exhaust).