The BBD is a 2-barrel carburetor manufactured by Carter.
BBD carbs were not stamped with the carburetor number. You'll find the carb number on a tag attached to the carburetor by one of the bowl screws. If you don't have the tag, you'll have to take the carburetor apart so the gaskets, accelerator pump, and needle/seat can be matched to a kit.
There is no way to identify a BBD kit from the outside of the carburetor.
Carter manufactured two main styles over the years.
AIR BLED The air bled circuit used prior to 1974 has an emulsion tube or vent tube that extends downward into the high speed well. This tube mixes air with the fuel before it leaves the high speed well. The air bled design always uses “down hill” nozzles. The air bleed in the high speed circuit also serve as-an anti-percolator passage.
SOLID FUELThe solid fuel design, 1974 and ‘later, takes solid fuel from the high speed well and bleeds air into the circuit at the top through the extended vent tubes located in the cluster, closer to the tip of the nozzle. The solid fuel design always uses “uphill” nozzles and gives a closer calibration to meet the emission standards and also serves as an anti-percolator passage.
