The Autolite 2100 is a Foorrdd designed Holley built 2 barrel. While almost bullet-proof (and unlike other Holleys, they don't leak!!!), we will never again migrate one from one application to another; due to a total lack of literature and tuning parts. This is really an excellent carburetor. Too bad that Autolite was a "captive" Foorrdd company, and retail literature was not printed.
As far as the Carter 2-barrels are concerned, the BBD is VERY difficult to modify. The WGD will accept AFB jets and vacuum piston springs, so some tuning parts are available. The WGD is also a superior design, and much more reliable than the BBD series. The older (40's and 50's) WCD series are much easier to modify.
As to CFM, you pretty much have to guess. As these were O.E. applications only, Carter had no reason to publish CFM ratings, and didn't.
Carter did make a very few WGD aftermarket carbs (55 Chevy and VW bugspray to name a couple), but parts for these are different than for the O.E. WGD (read rare and expensive).
Jon.
