I know that there's supposed to be an audible and seat in the pants difference when the secondaries blow open. They are mechanically actuated when you floor the pedal correct?
Problem is, there is no kind of sensation of them opening when I floor it. The car just gradually speeds up. I could feel the point in the pedal that the mechanical linkage is engaging the lower secondary valves.

Could it be something up with the choke preventing the top flaps from opening? Here is a video of the choke air valve rod at idle right after a 30 mile drive. I've been driving around with that front tube capped (yellow cap). It's supposed to go to the hot air valve on the carb cover, but I'm running headers so I figured it'd be pointless to have it hooked up.

Vid:

In this vid, I hook up the hose from the carb cover.

Is the vacuum break keeping my secondaries from opening?

-Edit-
https://www.thirdgen.org/quadrajet
I know for sure I played around with the tension screw before. Think I adjusted it wrong.

Also, the car has weird idles when "cold". The choke definitely has to be misadjusted. On cold startup it could be either the regular 750RPM or somewhere ~1400. If it starts up with the normal 750 RPM, it'll go up to idling at ~1400 RPM after a short drive down the road. Even after a 20 minute drive it'll idle at ~1400 RPM. Most of the time though, it runs the set 750 RPM.

 

The AV opening is controlled by a combination of the vacuum break, and the AV spring tension. When you go WOT, the secondary throttle blades open, but the AV remain closed. As manifold vacuum drops, the vacuum on the vacuum break is lost (pretty much like your video shows). This allows the AV to open gradually, so that the fuel can catch up with the air flow in the secondary metering circuits.

In general, if you can "feel" the secondaries opening, they're opening too quickly. But, if the power comes on too gradually, or not at all, then adjustment of the AV spring tension, and/or "tuning" of the secondary rods & hanger, may be in order.

For comparison, you could tie the AV closed and see how the car accelerates. You'll most likely find that it will be much less powerful than it is now.

 

Agreed. It's tough to test this on the bench or idling in the driveway. Believe me, if the secondary throttles are opening when you mash the pedal, the air valve WILL open.

Your vacuum solenoid on the pass. side is operating perfectly. If it was "frozen" in one position or the other (open or closed) you would have problems, but yours is fine.

The only thing that can prevent the secondary throttles from opening (aside from them being rusted shut from sitting outdoors in the rain for a few years) is if the choke isn't opening fully. There is a secondary throttle lockout arm built into the choke linkage (passenger side) that prevents the secondaries from opening any time the choke is on, even a little bit. If the choke is fully open, that lockout arm retracts and it's all based on the mechanical throttle linkage on the other side of the carb from there out.