The Stovebolt Site Forums The Shop Area The HiPo Shop 383 "New build" smoking

I join with Jerry on the valve guide idea as the main problem.

Also there could be a secondary problem...Did you use chrome piston rings? About 50 years ago I used the last of those I will ever put in any engine. You can see an image below showing the hatch marks are still visible. The engine had over 25,000 miles on it when I removed it. The rings never did break in correctly. Just another thought.