I was told that if it blows to atmosphere I have just created the worlds biggest vacuum leak. My understanding, which could be wrong, is that the stock setup works just as WO23Coronet explained but that my Holley setup would not perform this function. L4staero, I would like to know more if you could help. And Goody, I'll do some research on your idea also. This build has been fun but so many little details, technical things, have me rethinking. I want to get it right the first time. Thanks everybody and I'll keep checking for further feedback.