Valve guide damage
 

Working on a set of heads with fairly new guides and see this damage on the inside bores. What would cause this? Improper install, reamer, honing? They did reuse the original valves

Thanks
Craig

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Maybe a burr on the valve keeper grooves and someone was twisting the valve out?

Or the rings and ridges are on purpose the "tighten up" a loose guide for a few more miles with out replacement, ie MotorMiester head rebuild.

Likely. Knurling the valve guides to tighten them up was common in the days of cast iron heads without replaceable guides. In old school engines, it worked well enough. When the head was rebuilt, the guides could be knurled if they weren't worn out, or bored oversize and oversize valves installed, or bored out and new guides pressed in.

If it's spiral, maybe the reamer had a burr.

Looks like they used a standard machinists reamer which is only suppose to travel in one direction IN and they used it IN and Out like a brush hone.