If you are getting black smoke when you jump on it then its a rich bog.
The accelerator pump can provide to much gas and cause a bog as easily as if to little gas is provided. I would start looking at the pump squirter and the pump cam. If its a used carb go to the holley web site and look up the list number and find out what size was stock for the squirter and the cam and go back to stock as your first step. If its new then go down one size on the squirter or try a less agressive cam.
With black smoke it wouldn't be the secondaries causing the bog. Vacuum secondaries do not have an accelerator pump so you need to keep the air velocity up to have enough signal to draw fuel. When the open to fast the air velocity drops and no fuel is drawn and you get a lean bog.
