Good answer Glenn. I considered a Q-jet a while back, asked a bunch of questions of some knowledgeable folks, got some answers that I really didn't want to hear and decided that an adapter/spacer really didn't make much sense on a Ford 4 hole Performer RPM intake. Sooooo now I have a $20 swap meet spare Performer 600cfm, 1405 that has just taken a Berryman Carb cleaner bath and will be reassembled to as new and just waiting its turn