Make sure that the distributor has no vacuum going to it at idle. If it does then your getting full timing advance at idle. If you have or can borrow a vacuum gauge check the ports on the carb till you find one with no vacuum at idle, that's what you want. Anything else will be manifold vacuum, about 11 to 18 inches of vacuum at idle. Other than that just check for vacuum leaks and hook everything back up like it was with the Holley.