Hello, I'm new here and just had a question. About a month ago I rebuilt my 300ex that was smoking. Went great, started, drove, and sounded amazing! Now it's like 20 hours and it started smoking again. Tore into it. Rings were shot. I was told my cylinder was egg shaped and to bore it 2 over. Does he mean .02 or .04? And will boring it over affect my reliability?

 

Every cylinder will have a max tolerance as to how much of an over bore you can do before it needs to be resleeved or replaced. Reliability should remain intact unless you go crazy with other mods like a cam or real high comp piston. 2 over is vague to me. They could mean inches although mm seems to be popular these days as well. Whatever shop you have do the work should be able to do the smallest over bore that keeps you in spec, and point you to the proper size piston, rings, and gasket kit.