The Holley 2100 series are two-barrel downdraft carburetors first used on Ford, Mercury and Lincoln products, including Ford trucks from 1934 to 1956. Various versions were used on GMC, IHC, Mack, REO and White trucks into the 1950's, including the governed AA-1G and 852FFG models.
The best known automotive version is the Holley 2100 used on Ford flathead engines starting in 1934. This carburetor uses a three bolt flange, shared with the Stromberg EE-1 ('97'). This carburetor was produced for Ford and is often found with Ford script markings on the float bowl, in which case it is referred to as the AA-1 model. The 2100/AA-1 carburetors are often referred to as Ford 94's due to the '94' marking on the back of the float bowl, which refers to the venturi diameter in inches. More information about Ford flathead fuel systems.
A similar carburetor was referred to as the Chandler-Grove 91 or 99 model (after the original designer of the carb) and was used on Lincoln V-12's from 1937 to 1948, as well as 1938-1942 90-100 HP Ford flatheads. The smaller 81 model was used on the 60 HP flathead in 1937-1940.
The 2100 DD variant appeared in 1952 and was last used on the 272 CID motor in 1955. The 2110 EE was used in 1956 and 1957 in Ford trucks in 1956 and 1957. These used a conventional four bolt flange.