Originally Posted by Plaintoast
I've heard this old wives tale for years. even had a shop owner ask me not to do "too" good of a job on a head rebuild citing that very reason.
i have not yet seen any evidence of it being true.
if you think about it, i can understand where that's coming from, but again, I've never seen any proof.
Way back when dinosaurs ruled the earth and I was going to college, I worked in an all night shop in San Luis Obispo. I drew a job one night to do a top end rebuild on a high mileage 55, 265 Chevy. When I got the heads off I could see the pistons moved about as much sideways as they would up and down. I told the foreman that the engine was shot and doing a top end would just make an oil burning, smoker even worse. He said to just get on with it which I did, buttoned it up early in the morning hours took it for a test drive. It left a thick cloud of oil smoke for several miles. I took it back and wrote up a report sheet that basically said rebuilding the top end only made its smoking habit worse. Next day it was gone. Day after that it was back in my stall with instructions to pull it apart and rebuild the bottom end. Did that with an overbore, new pistons and rings, new bearings, etc. Put the heads back on fired it up no smoke no oil consumption beyond what you'd expect for breaking in the rings.