K321 2 questions

[MalMac 1,332]

Started tearing down a K321 for a rebuild. This is off a tractor that was recently purchased and I really don't know the complete history of the machine. While taking the valves out I had the exhaust valve stick. Now I have had them be somewhat a little sticky before but not like this one. I had to literally tap the valve out. It started to pull out just fine then it was like hitting a brick wall. I could not get it to move any farther. Almost like the end of the valve had become mushroomed and would not slide out the valve guide. I got it out but not without some muscle. What caused it to be that bad?

2 question, I noticed in bore on the cylinder wall a very small small nick. Upon investigation it appears to be a flaw in the actual casting. It is about a 1/64 x 1/64 maybe .030 deep if that. I know this engine will be bored out but very unlikely it will remove the flaw. I was wondering if the flaw will even bother it. I don't think it did before. I think the PO got the engine too hot and started in ruining the piston. Other parts show signs of being too hot. So should I just ignore the little flaw or start looking for a different block?

[TT-(Moderator) 1,162]

If a valve hangs up during removal, I dress the stem with a file. Even if the stem tip isn't mushroomed, (it happens) the keeper groove can get a wicker that will hang up in the guide.

As far as the mark in the bore goes, you'd almost have to see what it looks like after the machine work. The depth of a scratch or other defect is often deceiving, so you might get lucky.

If it's not something the rings can catch, it might be fine.

[MalMac 1,332]

I did not even think about the keeper grove getting a wicker on it. Never had it happen to that extent before. Hope I did not put a groove in the valve guide getting it out.