It might have no effect on the idle circuit, but yes it should go richer in the upper rpms.
It may also delay the start of the mains, creating a lean transition.
The air bleeding into the main well lowers the overall density of the fluid mixture. So sometimes enlarging the main bleed brings in more fuel earlier - which shows up as richer AFR.
Going from very small or no bleeds to ideal size bleeds will do the same.
That's what this fig 11-11 from Obert shows.
Yellow highlights the start up with too little or no e-holes, and then that would also mean the main air bleed can't compensate for increasing draw at highest flows.
View attachment 1715379641
Emulsion Tuning
