Originally Posted by jayd_2
I've got a 1989 SBC that was a rebuild that had about 5000 miles on it when I got it. It runs great but uses oil and fouls the number 8 plug but does not smoke. The plug fouls after several hundred miles, all the other plugs are good. I just replaced the valve stem seals on number 8 but I doubt that was the problem. It uses half a quart in about 300 miles. The oil pressure is 30 lbs at idle and 60 lbs at rpm.
It doesn't smoke when cold or when under a load or when you let off at high rpm. How it could use so much oil without smoking? There are no oil leaks and the crank case pressure is good, pcv valve is dry.
Is it possible that the intake is leaking on one cylinder, it's got an aluminum intake and I've heard some gaskets are too hard and don't seal well on aluminum.
It could be a leak from the intake into number 8 but before pulling the intake off remove the rocker cover on number eight's side roll the engine over and observe the rocker movement to see if a cam lobe is wiped out.
Also, a vacuum check before diving in, a leak into the manifold should show a low but steady needle on idle that corrects as the RPMs come up. A wiped lobe will show a normal needle that dips everytime that cylinder comes around and stays that way as the RPMs are moderately raised.