1 irritating problem with 3 circuit carbs is that the point of tip-in for the intermediate is the position of the hole in the body vs. the sweep of the throttle disc (not RPM or vacuum). This means that different engines size, static CR, cams, plenum volumes etc. need not only a difference hole size, but the hole "bumped" a bit forward or back to change the throttle disc angle at which the hole is exposed to vacuum.
IMHO some have already done this, but are not telling.

If you examine a "suspect" carb, look for a partial bevel or flat spot on the disc's edge where it passes the holes...


Boffin Emeritus