I have a 1969 Camaro SS with a 350, Holley double pumper. When I first start to accelerate there is a slight hesitation. I have checked timing, float level, new fuel filter and fuel pump. Made sure the accelerator pump is adjusted correctly and made an attempt to set mixture screws as correctly as I can. Any suggestions would be appreciated.

 

Is it mechanical secondary carb?

 

One of my first thoughts,also manual vacuum or electric choke?