Re-jetting is the term I meant to use sorry guys don't want to start a fight I don't really see why I'd need to re-jet it anyway I had it on a 302 and later on a 351w and it worked great. Also had the carb on a 460 but ended up sticking a 750 on instead(460 ran much better with 750) So it seems that a 600 is adequate for just about anything.