I have read that the 1407's and 1411's suffer from design flaws in the enrichment transition circuit. The way I understand it, the transition is set up too lean to keep up with the initial air increase when coming off the idle circuit. This seemed to jive with the issues I had, as I could adjust it to the rich side with the metering rods and seemingly help the stumble issue, But then I was constantly dealing with a rich condition at part throttle cruise as the enrichment circuit would stay open. I'd back off with the metering rod springs, and my rich condition would dissapate, but I'd be back to the lean-stumble when I first tipped into the throttle. (sound familiar???) This problem seems to be magnafied if you're car has headers and / or even a mild performance camshaft, as they weaken the idle vacuum signal to the carb, and make it even harder for the Eddy carb to sense the initial need for more fuel when the throttle is opened. In your case, the open plenum, single plane torker manifold would only seem to magnify this.

To me, the arguments FOR going to a Holley Carb are just way to strong to ignore. As I said, I fought with the same thing you're dealing with, actually went through (2) 1411 carburetors, both had the same problems. I thought for sure I was just a rookie and wasn't good at tuning yet... Finally switched to a Holley 80508, and within minutes, my car ran like I'd been thinking it should have been of for months!

I know you've spent money on this carb, and buying another is likely something you'd rather not do.... I hear ya! I'm just passing on my experience.