Originally Posted by stegman
I have a fresh 383 stroker in my roadster and after tuning and general cam breakin with a couple of short drives iam getting some blowby with and without the pvc. i know i should get some until its broke in, but it seems a little excessive to me. i pulled the plugs and they look even and pretty good telling me no broke rings. could timing effect blowby, iam running 76cc heads on 8cc dome pistons with a compression ratio of about 10.5 on 93 octane. does anybody think race gas or 100 octane avfuel would help. total timing is only 32 advance. thanks agian........
You need to break the engine in, short drives will not accomplish that. The engine and the oil need to get up to operating temps and stay there for a considerable period. You need about five 100 mile drives or one 500 mile drive at mostly moderate RPMs, with a few blasts on throttle to ge there. If you don't, it is easy to have an engine that will always have high blow by and perhaps oil consumption, though these are two different issues with their own as well as some common causes. What was used for rings is very important, chrome rings can be hard to seal up, these take more aggression on the throttle to bed them in than moly and certainly plain iron. A good engine builder would keep track of these things and advise the engine's owner/operator accordingly.
Short drives are very hard on an engine especially a fresh one. You can get a lot of blow by till the rings and cylinder walls get seated into each other. No 100 octane fuel will not help. If this doesn't settle down after a handful of long drives then you can start to consider problems in parts and/or machining.