http://mthobby.pcperfect.com/ch601/chengine6.htm

 

This is some rather interesting info on using a ea82 spfi intake manifold and modifying it to fit a weber to it with a built up adapter plate. This is off of a aircraft site but very interesting. Pretty cool idea since the ea82 spfi will out flow a ea81 and ea82 carbed intakes.

Personally I'd bet money that the intake manifold isn't the worst flowing component to an EA engine. I doubt there would be much power increase in the carb vs spfi manifold.

Or is there something I don't know?

I am not 100% on that but by comparison the runners look a bit larger. I would eventually like to try it using a seat dynamometer test.(Arse)