Factory GM Small Base 3x2 Carbs-Bigger Innards?

I've read or heard that the mid '57-'59 Olds J2, Pontiac Tri-Power, & Chevy 348 factory 3x2's (small base) had either a larger venturi or the venturi cluster bore is larger, or maybe both? Can anyone confirm or refute that?
Thanks.

 

http://victorylibrary.com/mopar/log-c.htm#2G

 

Panic, Thanks for the reply. I've read the info in victorylibrary.com before, but is that info. for a J2 carb or a regular Rochester 2 bbl? They refer to the factory 3x2 Rochester but I'd like to hear from someone who has taken apart & inspected, or measured a J2 or similar SB Rochester carb.

 

well, i dont know exactly the measurements, but the booster cluster IS different on "regular" carbs as opposed to tri power carbs. I had a "regular" carb on and it would not idle, so I pulled the booster cluster out of a tri power Olds carb and it idled and ran just fine. This is on a 348 and it will have a different vacum pull (I guess) than a smaller cubic Inch engine.
That did not clear up any Q did it?? LOL!!

 

Thanks Gonmad, any & all info is good.