I bought it new and we havent done anything but adjust the idle and the normal stuff, but yea that is the carb.
did the problem start when you put that carb on or has it been on for a while? you should be able to take the top off that carb with out spilling any fuel. it may be worth doing to see if there is fuel in the secondary bowls. also take the dist cap off and look at plates in the base of the dist. mess around with them. see if they are loose or if they are tight.
I would love to give one of these carbs a try out. I second the thoughts of, IF the throttles move ANY, the accelerator cam, arm and spring need to be adjusted to shoot 2 streams of fuel into the carb as soon as they move. That is the most often reason for a Holley based carb to have a bog. Then the secondary spring in the housing needs to be looked at and made sure it is the right spring. clint
