The hot idle position of the edge of the throttle disc (approximately mid-way between the "idle" and "transition" holes in the barrel) is universal among all carburetor brands, models and sizes. It's one of those factors that makes switching among non-OEM carbs a crap-shoot, and Holley has and will disagree that "loading" it more is an improvement (read their literature). If that were true, it would have occurred in the entire line 60 years ago. My guess: it corrected an existing (bad) condition, such as the blades were too far closed (in or below the "idle" hole) with that small engine to compensate for lower idle CFM demand.
