40 DCOM - Some online sellers claim that these are the "latest" design from Weber. Quite simply, they will not work properly on any engine apart from the Alfa Romeo they were designed for. They are an emissions style carburettor and also use a completely different pump jet design. In fact they use a diaphragm for the pump circuit similar to that used on the Dellorto carburettor. Having attempted and spoken with numerous customers, you may obtain the 40 DCOM carburettor cheap, but you will spend three times more trying to get it to even resemble working.
Late model 40 DCOE carburettor - Late model Alfa Romeo 40 DCOE carburettors are similar to the 40 DCOM in that they are an emissions style carburettor. There are many large progression holes and the emulsion tubes used are very specifc in that they are covered in holes. Many have attempted to tune these to vehicles other than Alfa Romeos with little success.But after reading this now I don't think the ones I have been looking at on eBay are any good.
http://m.ebay.com/itm/ALFA-ROMEO-WEBE ... -/291911405711?nav=SEARCH