Must be some other issue....main emulsion holes have nothing to do with idle characteristics.I just hope it’s not this AED 750 carb. I found a few complaints online about them idling pig rich. Not many but they are there. Something about too many emulsion holes.
This is along the lines of what I would be looking at.....just hard to decide the choice of drilling holes first or making squirter changes first.I think you are on to something…. Leave the primaries to .020 transition where the 4 idle mixture screws like are become sensitive. Then drill the secondaries to close them to get rid of the lean backfire. Then add more squirter if needed.
Not to my knowledge.Could the fuel gotten sucked into the intake some other way?
If you study the fluid route through the metering block, you can see how jet changes will have no effect on idle.also, call me crazy. I know this goes against the carburator gospel, but I swear that switching the primaries from 77 jets to 75 helped clean up my idle.