The "falling on its face off idle" syndrome is a common one. It's exacerbated in engines such as the Ford Zetec which, due to their valve train design, take in a LOT of air, VERY quickly. The 45DCOE's were not particularly well designed for this, and the problem is one of a lack of fuel available just off idle (i.e., in the instant when the butterflies first open a tiny bit). There's a big slug of air, and not enough fuel to provide a proper stoichometric mix.
Weber, in concert with Webcon in England, has recently designed carbs that (reportedly, at least) completely cure this. They do this by adding a series of extremely precisely sized & located "progression holes" around the lower edge of the butterflies. These holes connect directly to the fuel supply, so instantly enrich the mixture at that critical point.
There are other Weber 45DCOE's that work reasonably well, too (although, not with the Zetec), having 3 or 4 progression holes. Older design engines often benefit from these carbs. The Alfa Romeo forums abound with information about this problem, and solutions sought. It might be worth browsing some of those sites for further ideas.
As I'm using a Zetec, with a very short, VERY non-restrictive manifold (I can clearly see all my intake valves through the carbs when I crack open the butterflies), the brand new design 45DCOE's were my only choice to get the engine running right, so I just recently bought a set & had them shipped over from the UK. They're specifically designed for my engine, in its current state of tune, so they should be jetted very close already.
_________________ Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit. http://zetec7.webs.com/
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