I purchased a Holley Street Avenger for my 302 engine that's going in my 65 conversion. It's the 570 CFM/Manual Choke. One thing I noticed on the carburetor is that it is has vacuum secondaries. I bought one for my 78 Chevy pick-up, and it performed better than the Edelbrock. That's why I bought this one for my 302. Would I have to purchase a Holley carb with mechanical secondaries or will the vacuum operated secondaries work?