This might help: I was helping a friend change intake & carb on his '84 TA. Went to a Performer intake & 670 cfm Steet Avenger carb. Engine idled at around 2,000 rpm and no matter what I did it would not idle down. Called the Holley tech line & was told it most likely a vacuum leak. The problem lies in the fact that the intake is designed for a spreadbore carb, the carb I was using is a square bore. I bought an adapter plate from Summit Racing Equip. that seals off the area that leaks. Problem solved. FYI: if you use this plate (approx. 1/16" thick) use a 3/8" drill bit to punch out the holes for the mounting studs to clear better. Seemed a little too tight.
