Sounds like a double venturi to me.

Posted by MRR on Sep. 17, 1998 at 08:41:46

In Reply to: HELP -- CARBURETOR -- HELP
posted by MGL on Sep. 17, 1998 at 07:33:45

It sounds like you have a Holley double venturi carburetor.Which was a variation of the zenith that is original to the Model A.Your carburetor is a somewhat rare example of the original.The bb has had recent conversation regarding these guys.Look below to for a posting by Kevin Daly.I have opined (for what it's worth) on what to do.
A bit of advice.Don't paint the inside of the carb.
E-mail me if you have further questions.
MRR