Posted by Matt Wilson [172.69.68.48] on Saturday, December 29, 2018 at 01:29:19 :
I'm at the point of checking all the machine work, parts dimensions, etc., for a 265 engine rebuild that I'm doing, and I discovered a few nicks on the walls of cylinders 3 and 4. There are two nicks in each cylinder. The smallest is roughly circular, and about 1/32 across and maybe a thousandth or so in depth (just my estimate by feel and looking under magnification). That one almost seems like a possible casting flaw that broke through when the cylinder was machined oversize.
The others are all between 1/16 and 3/32" in length and are at an angle to the cylinder, so not vertical like scratches one often sees due to ring end gap burrs or contaminants, but not quite lined up with the crosshatching either. I can catch my fingernail on one or two of those, and the others I can feel with my fingernail or fingertip, but not catch with my nail. I estimate the deepest ones are 0.002 - 0.004", although I could be off on that.
All of the nicks are separated from each other by a fair distance, and there doesn't seem to be any raised material next to them.
I plan to talk to my machinist about it and see what he says, but I wanted to get your opinions as well. From a performance standpoint, those are so tiny, they shouldn't matter at all in the sense of holding compression or letting oil get past, but I'm more concerned about whether they will shorten the life of the rings.
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