1971 360 question

I've never owned a car where choosing a PV based on half of idle vacuum was a good starting point. They're better off just choosing an arbitrary number as a "starting point," which is pretty much what Holley does since most new Holley's come with 6.5 PV's.

Anyone willing to tune the PV should know that the opening event is based on vacuum when actually driving, not sitting at idle. Using idle vacuum as a starting point is just ignorant.