A couple of comments on this subject:
Shipwright and I did have a conversation concerning the Stromberg and Zenith carbs with adjustable jets. By the way, Shipwright, there are many others with adjustable jets ie Marvel, Tillotson, Rayfield, Mallory, and probably more; but these carbs for the most part were sold to customers too frugal to purchase a repair kit for the original carb, so will not discuss them here. Carter also made a carb with adjustable main metering jet, but it is not one we recommend.
The whole subject of adjustable main jets is largely misunderstood; in fact the term itself is misleading. In general, when a carburetor is fitted from the factory with an adjustable main metering jet, the design is to install a larger than stock FIXED main metering jet and an adjuster which will restrict the fuel flow (there are other methods). There are some either "less than knowledgable" or "less than ethical" individuals that sell an aftermarket adjustor, which will do nothing for a richer mixture unless the fixed main metering jet is changed.
Generally (there are exceptions), the adjustable jets came from the factory on "universal, replacement" carburetors. Taking an adjustor from one of these, and applying it to a carb not designed for the adjustor doesn't necessarily work.
The one barrel carbs with the adjustable main metering system which we recommend (we have some of the others, should any wish to disregard this advice LOL) would be the Stromberg "B" series (at least one company made a good "B" series carb LOL) and the Zenith 28 and 228 series carbs. These come in two different physical sizes: S.A.E. size 2 (nominal 1 7/16 bore, 2 11/16 center to center) and S.A.E. size 3 (nominal 1 5/8 bore, 2 15/16 center to center). Each size comes in at least 2 different internal venturi size, and several different configurations; so one MUST be careful when selecting these to match them for use on a multiple carb setup.
As to aircraft carburetors; as I do not have FAA certification, I will NOT discuss aircraft carburetors other than the following: (A) we have one of the worlds largest librarys of USA produced aircraft carburetor reference books (some internal manufacturer items which are one-of-a-kind) for sale; and (B) typically, parts for aircraft carburetors seem to be priced at approximately 10 to 20 times their comparable automobile counterpart.
Jon.
