I’ve read that the primary throttle transfer slots should be adjusted “square”. That appears to mean that the throttle plates are at the point where the transfer slot (as viewed underneath the carb) is as tall as it is wide. On my carb, this alignment occurs when the throttle plates are completely closed and primary throttle idle screw backed all the way out. I wasn’t sure this would work, since I’ve always had to screw in this adjustment screw to adjust the idle. But it seemed to work for my engine. With the primary transfer slots square and ½ turn on the secondary throttle screw, the engine idles at about 800 RPM when warm.

Last weekend, I adjusted the idle mixture screws. Previously, these were 1.75 turns out. I left them at 2 turns out and achieved AFR of 13.3 (air cleaner on) and vacuum of 19.5 in HG at 840 RPM. Now that I’ve adjusted the primary transfer slot openings and the secondary throttle stop, I should probably take another look at the idle mixture screws, but will leave them alone for now since I hate that adjustment process on a hot engine.