Running that undersized Holley on a bored-out 261 is like duct- taping soda straws into a runner's nostrils and sending him out to run a marathon. If the engine can't breathe, it can't perform, and no amount of jetting tinkering is going to give the engine the air it needs. The adapter is a further restriction that you just don't need. Trash the Holley and the adapter and put a real carburetor on that engine. When somebody is going to solve all my problems with something he just happens to be selling at the time, I have a tiny bit of difficulty believing him. What did that Rube Goldberg carb/adapter setup cost you, anyway?
Jerry
