Well, I think I do an experiment with it on and off and see which one seems to be better. It's just that looked it up on line and I noticed that the sbc had a pcv a lot more than the BBC. That's why I was asking about it. I don't see why one would have one more than the other. The BBC just had two breathers and the sbc had a pcv valve. So ill do that and report back to see what y'all think. Thanks for the opinions and suggestions. Maybe a pic of your BBC vent systems.