My question was a valid one. Barry treated it as such. I have a '67 Mercury that came with a 350 cfm 2V on its 390. You can accelerate it in second gear until it just stops increasing speed. I wonder what the mixture is doing.
I actually thought you were joking when you posted the original question..... *shrugs*
When it became obvious that you were not joking and were serious I asked the question of how an engine gets it's fuel from a carburetor. Not for the sake of delving into theory, it was with the intention that you would figure out how to answer your own question, as that is often more rewarding than being spoonfed an answer that you may or may not believe anyway.
So Drew, I realize spending a month on a tuna boat in a sausage fest with all those sweaty mens gets you a little askew, but let's not get into theory. Just the facts, ma'am. Put a stock 350 cfm 2V on your Galaxie and run it down the road in 2nd until its done, and data log the A/F so we know what's really going on. What is learned, is learned by all. Don't let your ego get in the way. Again.
If this was your idea at humor, I'll admit, I don't really get it, seems like you were trying to be intentionally insulting so I just ignored it. If this was indeed your idea of humor, I can see why you do not find the place very funny.
I haven't bothered datalogging anything as I'm too lazy to drive around with a laptop attached to the O2. I still visually note the O2 meter and have tested out literally hundreds of carburetors in the last few years this way. There is certainly a lot to learn from this, more to learn by making big changes to the calibration and seeing where and why the engine does what.
My LM2 has the capabilities, and one of these days I'll do it with some of the more common carb combinations I build just for the sake of having a print out.
Running out of air, is running out of air.
Carburetors meter fuel into the air as it passes the venturi, calling it sucking/blowing/depression/etc is just semantics and not terribly important to the fact that if air becomes the limiting factor it wouldn't go lean unless there is a calibration issue or the carb is magically getting unmetered air from somewhere else.
Calibration issues like jet/pvcr too small, HSAB/emulsion waaaay too much, etc. (or as Chris mentioned, the engine is running out of supplied fuel)
As Barry mentioned, if anything secondaries not opening cause the engine to go rich due to pulling harder through the venturi than the carb was designed for. Maybe some instance does it differently, but I haven't witnessed this.