RE: Fox Eagle III .60 Diesel Conversion
Well, the Fox engine has a thick cylinder wall and a large flange on top. So if you manage to overtighten the screws somehow, if there is any distortion it is limited to that very top edge of the cylinder and it wouldn't propagate down further into the cylinder. it looks like Fox thought about that when he designed the engine years ago.
The portion of the cylinder from TDC to the top of the ports is the high wear section and the actual highest wear place is right at the top of where the ring would stop at down maybe 1/4 of a inch. Below that point the piston is running at around its highest speed down to near BDC where it slows down again. So it really begins to look like that part where the blowby marks are showing is very highly worn out more and the ring is weak and has developed a wavy pattern to it, maybe a poorly fitted ring gap didn't help it any. There may have been some poorly done cylinder honing in the past and that didn't help it out any.