I just picked up a 2bbl holley, I think the part number is 12r 3975 b, I might not have the right number there though. My question is: The lower set of butterflys is not opening very far. I can't see anything that makes them stick on the outside so I was thinking its somthing on the inside that prevents them from moving. I don't have a rebuild breakdown sheet or the money to buy a holley book at the moment. Any help is much appreciated all, thanks for your time.

-Harribos