Weber Carburetor - Weber Carburetor Designations - Model Codes

Model Codes

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, the 40 DCNF and 40 DCOE both have 40 mm throttle plates. The rule that the prefix refers to throttle bore diameter is only one of two sure-fire rules in Weber 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 and O means orizzontale (vertical and horizontal, respectively). The 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: the 45 DCOE9 is a variation of the 45 DCOE. But, note that, to date, there are 10 known variations of the 45 DCOE9! SO Weber carb nomenclature is chaos. To return to the IDA, there may be three, as well as two throats, and there is no choke at all. Here is one last example of how the terminology collapses. The 40 DCO carb fitted to the early Alfa Giulietta Veloce follows the nomenclature exactly. It is a double-throat horizontal carb with 40 mm throttle bores. The 40 DCOE of later Alfa use, however, is neither die-cast nor equipped with an electric choke. In this case, the E indicates a trapezoid mounting bolt pattern instead of the rectangular one of the DCO.