The Stovebolt Site Forums The Shop Area Engine Shop # 5 cylinder fouling

I know I have many issues with my 55.1 235 engine as far as oil consumption and smoke. I found a mechanic sort of local who will look at it and i'm sure he is going to ask me questions about the motors behaviors. So i will tell him what I think I know, but i don't know why it runs great with some smoke and than after three months runs like poop and smokes like crazy. I change the #5 spark plug and it all gets better. So much oil on that plug, but compersion is close to other cylinders. I will ask him to do a leak down test as per advise from other bolters and if he dosen't do leak down test I will try to find another mechanic. Most of them say "put a 350 in it"

The oil control ring on that cylinder could be bad. That would let oil by and compression could be similar to other cylinders. A new ring set on that cylinder may fix it up.

Use a borescope through the spark plug hole to look for score marks in the cylinder. A ring cannot seal properly if there are scratches that let the oil bypass the rings. Also, a worn intake valve guide and/or valve stem seals that let oil trickle down the valve stem can create pretty noticeable oil consumption and plug fouling. DO NOT let anyone convince you to install something called a "spark plug anti-fouler"- - -a spacer that moves the plug away from the combustion chamber. It also lets the plug overheat and burn the electrodes away in a hurry.
Jerry