All Weber carburetors carry a model number stamped at the base of the carburetor on its mounting flange or on the top cover. A Weber carb is designated with a series of numbers, then letters, then sometimes, more numbers. The first set of numbers is called a prefix, the second set, a suffix. The letters in between seem to be the first letters of Italian words, but not always. The prefix always indicates the size of the throttle plate. For example, in this case the 30 of the 30 DICA refers to a 30 millimeter throttle bore diameter.
The rule that the prefix refers to throttle bore diameter is only one of two sure-fire rules in Weber carburetor nomenclature. The other is the jet-numbering convention described later. The letters immediately following the prefix refer in Italian, to the general type of carb. Only a few terms are consistent:
- DC means doppio corpo, or double-throat
- V means verticale
- O means orizzontale (vertical and horizontal, respectively)
- I in IDA seems to mean invertito, or inverted. Yet, there are no up-draft, or inverted Webers: the IDA is a downdraft.
Other even less-consistent single-letter designations are:
- E – Die-Cast carb
- F – Ford (or Ferrari?) application
- V – carb with a power valve
- A – Water-operated automatic choke.
Any numbers following the letters are variations of the basic type. So it would seem that the 30 DIC is a 30 millimeter double throated inverted carb and the -1, -2 … are just updated versions with some modification that was big enough to warrant a designation.
In this case, my little Weber Carburetor 30 DICA would be the water operated automatic choke version of the 30 DIC.
See the Wikipedia Weber Page