There are three basic models of the Rochester 2 barrel carburetor. They are 2G, 2GC and 2GV. 2G simply means that it is a two bore carburetor. Typically the Rochester 2 barrel carburetor is used on V-8 engines where each bore supplies air and fuel to 4 cylinders through a divided intake manifold. Two different throttle body flanges are used on the 2G carburetor, 1 1/4" & 1 1/2". Larger engines use the bigger 1 1/2" bore sized flange.

The 2G carburetor is equipped with a manually operated choke valve. Its major applications are on truck and marine engines where an automatic choke is not necessary. The 2GC is the basic 2G carburetor except that it has an integral choke (meaning it is mounted on the carburetor). Some were mounted on the air horn, and others on the throttle body. The 2GV is also an automatic choke model, however, a vacuum break diaphragm unit is used in place of the conventional choke housing and choke.