WCFB: White Cast Four Barrel, for the metal used for the mainbody and top castings, white (or pot) metal.
AFB: Aluminum Four Barrel, made of aluminum.
AVS: Air Valve Secondary, for the secondary air brake type difference from the AFB.
TQ: Thermo-Quad, thermo-plastic main body.
Think about it, why would they call it a WHITE CAST four barrel when it's not white cast,or even pot metal, it's Wrought Iron.Mind you some had either iron or aluminum throttle bodies but Aluminum is not white cast or pot metal.Plus an "WCFB" is 18lbs and an "AFB" is about half that due to it being Aluminum and not Wrought Iron.
The WCFB, introduced in 1952,was comprised of three basic
castings: a cast-iron throttle body, a zinc main body, and an aluminum air horn,no pot metal no white metal.
The offical company line in the 1970's and 1980's (before Federal Mogul) was Will Carter Four Barrel (see the Dave Emanual book "Carter Carburetors").
http://www.amazon.com/Carter-Carburetors-Dave-Emanuel/dp/0931472113
Carter Carburetors beginning in 1932 had a type designation beginning with a "W" and had iron bases. These include the W-1, W-2, and WA-1 single barrel; and the WD-0 (zero, not "ohh"), WCD, and WGD two barrel.
Aluminum is it's own material, pot/white metal are mixes of metals:
"POT METAL"
Pot metal is a slang term which is used to refer to cheap metal alloys with a low melting point. The low melting point makes pot metal very easy to cast, but the generally low quality can cause problems during casting and at a later date. Because there is no formal definition of pot metal, it can be hard to determine its contents. Some common metals included in pot metal alloys include: zinc, lead, copper, tin, magnesium, aluminum, iron, tin, and cadmium, among others.
"WHITE CAST"
The white metals are any of several light-colored alloys used as a base for plated silverware, ornaments or novelties, as well as any of several lead-base or tin-base alloys used for things like bearings, jewellery, miniature figures, fusible plugs, some medals and metal type.
Some of the metals that make up a white metal are antimony, tin, lead, cadmium, bismuth, and zinc. Not all of these metals are found in all white metal alloys but are mixed to achieve a desired goal or need. As an example, a base metal for jewelry needs to be castable, polishable, have good flow characteristics, have the ability to cast fine detail without an excessive amount of porosity and cast at between 230 °C and 300 °C (450 °F and 575 °F).
And just to toss another wrench into the mix, not all AFB carbs were Aluminum some were in fact cast out of zinc............So should we call them "ZFB" Carbs, ha ha