Holley or Edelbrock carb

As far as I can tell, it seems to be a modified AFB. The air door for the secondarys is able to be adjusted for it opening rate. On OE, AVS carbs, theres a screw that holds the tenstion spring. The tenstion spring can be wound tighter for a later opening or loosened up for an earlier opening. I think this is an advantage. Not to mention a few more cfm.

On the performer, the weighted air door can be made lighter for a quicker opening. But putting weight back on. Now thats different and not so easy for everybody. I have several secondary air velocity doors to lighten up to experiment with. These doors are not able to be purchased seperatly.