Actually, we're both wrong regarding the TQ. I've always called it a vacuum secondary, but that's not entirely true. It's not mechanical either. Just like the quadrajet, it's a hybrid. The base plate is mechanical, yes. But the vacuum door controls the whole show. It can be controlled by rate of opening and amount of opening. You could essentially cut the secondary side OFF with the air door adjustment. That's NOT a mechanical secondary. And true, since the secondary throttle plates are not controlled by vacuum, it's not a vacuum secondary, either, but the secondary side is certainly controlled by vacuum, but not actuated by vacuum. The vacuum of the engine itself pulls the air door open. The vacuum of the engine also slows the door through the vacuum brake/choke pulloff, so vacuum plays a huge role in how the secondaries work, UNLIKE a 100% mechanical secondary carburetor like say, a Holley double pumper. THAT is a true mechanical secondary carburetor. The TQ and Q Jet are not.
