[Gunner]

I haven't opened the distributor but from glancing at the MSD charts, I'd say it's running either two light silver springs or (more likely) one light silver and one blue. That matches the approximate (very quick) curve I've encountered. It appears to have the 21* stop installed (although I'm getting closer to +23* total). I can see where going to the 18* stop and 20* initial might improve things; I will experiment. Since I can't get the curve much faster than it is I'm betting against it being a factor.

I baselined the idle mixture by bringing all four screws out to one turn and working from there with a vacuum gauge. Let me go check... grumble can't find a rassafrassin' flat driver... yeah, I'm 3/4 turn out on them. The vacuum peak is pretty sharp at that point; an eighth turn in won't sustain idle and a quarter turn out loses 20% of vacuum. I fiddled around quite a while with idle speed and the corner screws. Since I never had any trouble with the idle other than at the very lean end the Idle-Eze adjustment never had much effect; I left it at the original setting. I've only got 10-11 inches of vacuum; I could try bringing the screws out a bit and see but all things considered, it doesn't sound like a fix.

Zoom This, right off the bat I'd say an 850 is too much carb for a 418, even if it's got a 7k redline. A 750 would seem optimal; why did you go down so far in size?