I simply cannot find myself agreeing with any form of idle air screw adjustment screw turn counts. You adjust idle mixture screws with a vacuum gauge, based on highest engine vacuum at idle. If one screw is two turns out and another is 3.5 turns out and the vacuum gauge reads highest, so be it. Every combination is different. Trying to box in adjustment based on screw turn counts makes no sense to me. Also, every carburetor manufacturer clearly advises using a vacuum gauge to make that adjustment. It just "works".