I have a 1979 Jeep CJ-7 with a 1985 Chevy 350 engine out of a Chevy G-20 van. The carb is a quadrajet. I know for a fact that the rear butterflies (secondaries) don't open, even when you floor it, at any speed...WTH is going on? The choke works, and the vacuum module pulls in but the rears don't open. I know the rears don't work because I took the hood and air cleaner off and watched.