The vacuum leak is where I said, your secondaries are probably open too far. This will make the carb run on the secondary transition slots and negate the primary mix screws you are talking about. It will also negate your primary idle adjustment screw below a certain point.

You need to find the stop for the seconardies. It is a screw often facing the intake which makes it near impossible to adjust with the carb on. Anyway, you need to see it the secondaries are being stopped from closing with this secondary idle screw. If so back it off so it does not. Then set you idle mix screw to 1/2-1 turn out and adjust up the idle screw to get the correct idle rpm. You don't use the 2 idle mix screws to set the idle btw.

Of course all of this is meaningly if an "eddie 1410" is not a knock off of a holley, which I suspect it is.

I have read that it's a Carter AFB clone, but I still think your onto somethin' here. I found a manual for it, so I'm just going to have to read it, and stare at the carb till I understand it. The manual says the secondaties are supposed to be opened by vacuum when the primaries are at about 60% open. We'll see.

Yep - messed with it again today - set the idle at 10* @ 1000 Rpm, thinkin' that's gotta be close. The idle mixture screws make no difference at all to idle until they are within 1/2 turn of the seat. If I push on the throttle linkage towards idle, idle drops. The only reason this thing is pretending to idle is the idle speed screw crackin' the primaries.... It has run fine for some hours, till I screwed the pooch pulling the dizzy. I don't see how I could develop a vacuum leak messing with that, but at 10* and 1000 RPM, I got 8". Clueless in Maine.

Have you verified the firing order of the wires on he cap, specifically 5 and 7, I've seen them get reversed. Make sure all plug wires are in the correct firing order, also be sure the rotor is fully seated on the shaft and not wobbling inside the distributor. 1-8-4-3-6-5-7-2

I actually sketched the cylinders and cap, and numbered them on the cap and cylinders. Then I put the wire for each bank in a loom that clamped them, with most of the slack taken out of the plug side of the wires, so I'd know which wires went where without having to look it up. I'll check it out again, and see where 5 and 7 are. I do remember reading somewhere that 5 and 7 are prone to cross firing if they are too close or some such.