I have a 1970 442 with the stock Quadrajet & turbo 400 trans. I have the bogging problem when I really get on the gas. If I slowly push the pedal down the car has tremendous power.
I checked the vacuum break dashpot & found that it leaks. I got a new one. I adjusted the dashpot as shown in the repair manual. before changing the dashpot, I had been adjusting the
air valve spring to no avail. I set the air valve spring to 3/4 turns after the flaps just closes (like what it says in the manual). Again, no real change. My question is do I just keep making
the air valve spring tighter till it slows the flap opening? or is something else wrong. I'm sure this has been addressed before but my search didn't answer my question.

 

have you checked the accelerator pump for correct operation? If it's not squirting (enough) fuel, it can cause the symptoms you described.

 

I didn't check the accelerator pump. The carburetor was rebuilt about two years ago. That's a good idea. I will check to see if it's squirting.
Thanks for your help.