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Friends of Chrysler: Carter Carburetor

carter carburetorCarter Carburetor was established in 1909, and lived through 1985. Along the way, the company purchased Ball & Ball, a preferred supplier of Chrysler Corporation in the early days; both Balls worked with Carl Breer to dramatically improve their product and, by extension, Chrysler’s.

Carter was popular through the years, particularly from 1950-1980, and took a position of honor on Chrysler vehicles over the years — not just on the pedestrian models, where two-barrel BBDs were common, but on the very best cars Chrysler could make, Imperials and 300 letter-cars. Every Chrysler 300 letter-car reportedly used Carter carburetors.

carter logoThe company started with William Carter, born in 1884; like many young men with mechanical ability, he started out in bicycles, opening a repair shop at the age of 17. In 1902, after moving to St. Louis, he started experimenting with automobiles, discovering (like many others) that the carburetor was of supreme importance in keeping things going. He began to work with wooden molds, and eventually produced a cast brass carburetor of relatively high precision; it could meter and deliver fuel more accurately than many competing units.

Thus, the Carter Carburetor Company was born in 1909. It only remained in William Carter’s care for 13 years; then, American Car and Foundry, a firm older than Carter himself, purchased the company.

Carter BBChrysler entered the picture via Carl Breer, as previously noted; the Chrysler legend, on learning that the Ball family was planning to leave the carburetor business, set them up with Carter, which continued to produce the Ball & Ball basic designs (updated as needed) as the BB series [detail], starting in the late 1940s. These were used on every one of the comapny’s product lines, and would be divided later into BBS (Ball & Ball Single Barrel) and BBD (Ball & Ball Dual Barrel).

Carter was also asked to “militarize” single-barrel carburetors for the tiny Willys Jeep four-cylinder engines, waterproofing it for water crossings and making it possible to keep the engine going even when the vehicle was at a sharp angle. The result was the Carter Y-S carburetor (model 637S), which was later retrofit to other off-road vehicles. Jeep also used the Carter WA-1, starting in 1945 on the CJ series; and later on trucks. Starting in 1952, Jeep switched to the new YF single-barrel carburetors; in 1954, the 226 six-cylinder used the Carter WDG single-barrel. This was supplemented in 1958 by the Carter WC two-barrel. The company would rely on Carters through the 1960s and into the early 1970s, keeping the YF for a surprisingly long time.

Two and four barrel carburetors can have both primary and secondary barrels; the “secondaries” only open when needed for power.

Carter branched into fuel filters as well as related equipment, and sold “universal” carburetors to replace factory equipment on many cars.

carter wcfb carburetor

Carter created the first American four-barrel carburetor for Buick’s 1952 straight-eight, following up three years later with the WCFB (Wide Carter Four Barrel?). Two of these were used on the 1955 Chrysler C300, mounted atop the 331-cubic-inch Hemi engine. Dual WCFBs were also used on the similar 354 Hemi in the 300B, and then on the famed 392 cubic inch version used in the 1957 300C and 1958 300D (as well as other Chrysler Corporation cars).

WCFB carburetor

carter afbWhen the “old Hemi” was replaced by the 413 Wedge engines at the top of the Chrysler line, the WCFB carburetor was replaced by the four-barrel Carter AFB (“Aluminum Four Barrel”). Launched in 1957, it was used by AMC, Studebaker, various GM brands, Ford, and Chris Craft boats. The carburetor is still made by Weber for the aftermarket and restoration. Originals were identified by a triangular, aluminum ID tag on one of the fuel bowl screws. GM and Chrysler shared a separate, heated choke on the manifold, while other companies used a choke on the carburetor itself; all had the same air horn diameter (5 1/8 inches).

1950s fuel filtersThe AFB was well-designed for adjustments; the carburetor can remain on the car while the jets, floats, and metering rods are replaced, unlike similar Holleys, and both jets and metering rods are numbered, with the rods showing four digits — the first two for the normal diameter, the second two for the power diameter. The system used a counterweighted air valve to slow the opening of the secondaries; it was effective but one could not adjust the time it took for the secondaries to open.

From 1968 to 1971, Carter sold a carburetor named after its air-valve-actuated secondaries (the AVS — “Air Valve Secondaries”) — which did allow owners to tune the time it took to open the secondaries. They were also more responsive due to other design changes. The AVS could replace the AFB as a bolt-on; they were used on Chrysler Corporation cars only (except for the 1968 Chevrolet 275-hp 327 — thanks, “CBody67”), on the 340, 383, and 440 engines. The AVS did not necessarily make more dyno power than competing carburetors, but was generally a better design on the street, and would later be brought back by Edelbrock.

Hemi Andersen wrote: “When people buy performance carburetors these days, they buy a lot of the Edelbrock, which is the old Carter. They are shinier and prettier now but most are the AVS (Air Valve Secondary) type as I recall. I don't see a lot of Thermoquads except on ‘original’ survivors. When people replace Thermoquads, it is usually to ‘spread bore’ Holley carbs.”

The final Chrysler use of four-barrel Carter carburetors was the Thermoquad, which used a lightweight plastic body, and was elemental to the most powerful Mopars. The Carters were generally seen as less “finicky” than the Holleys. The company still used Carter BBS and BBD carburetors on its non-performance engines, along with Holleys, depending on the year.

Jeep continued to use the Carter BBD carburetor on its 4.2 liter (258 cubic inch) six cylinders in the CJ and Wrangler series, right until the 1990 model year; in 1991, the Wrangler finally got the fuel-injected 4-liter six. Since the factory had closed, these carburetors must either have been built and stored, or produced by another supplier from the original molds. The latter may be more likely, since various other Carter carburetors were later produced by Weber and Edelbrock.

With the rise of electronic fuel injection, accelerating in the early 1980s, carburetors of all stripe became obsolete; even before then, Holley had been undercutting the company and Japanese suppliers such as Mikuni had become popular. In 1985, American Car and Foundry shut down the Carter Carburetor foundry, a year later ceding the PCB-contaminated property to the City of St. Louis.

The original Carter AFB designs are still in production, by Edelbrock; they are sold both directly and through Mopar Performance.

Some Carter carburetors used by Chrysler, 1974 onwards:

  • 1967-1975 Dart/Valiant export 225 slant six engines with “Power Pack”: BBD dual down-draft unit for 225 engine, 260 CFM. This carburetor was also used on Barracuda, “the Plymouth,” and “the Dodge” in 1969-1973. 1974-77 export slant six cars, and Dodge trucks, used the BBS with 163 CFM, model 7172S.
  • 1977 slant six cars with two-barrel carburetors: BBD 220 CFM units (varying based on carline, transmission, California, or export).In all cases, 1 7/16” throttle bore. Trucks used a BBD 285 CFM carburetor instead (model 8110S).
  • 1974-8 cars and trucks with 360, 400, and 440 four-barrel: various Thermoquad 850 CFM four-barrels, with different float levels and other adjustments.These all had 1.5” primaries and 2.25” secondaries.
  • 1974-8 cars and trucks with 318 four-barrels, including California and Canada: Thermoquad 285 CFM BBD units with various pump, unloader, and bowl vapor vent specs. These had 1.5” primaries and 2.25” secondaries.
  • 1974-8 cars and trucks with 318, 225, and 245 (Australian) engines: various BBD 285 CFM units with 1 7/16” throttle bores. (Slant six two-barrel started in 1977.)

Thanks for Kevin for reminding us that Jeep also used Carters.

Adjusting the Carter AVS secondaries

Rick wrote that on the AVS, “The butterfly valves on the secondaries are mechanically linked to the primaries. The secondaries are controlled by a spring loaded air door over the butterflys that looks a lot like a choke.” Scott Fluke wrote that, to adjust the secondary, one should start by setting it at 2.5 turns counter-clockwise from wide open.

The later “Thunder” version of these carburetors, made by Edelbrock, used a Torx and flat head screw on top on the driver’s side of the carburetor; one can use them to adjust the secondaries’ opening rate. If the engine bogs (gives a low growl, doesn’t accelerate, slowly starts to catch, then catches up) on full throttle, loosen the Torx screw while holding the flat head steady, then turn the flat head counter-clockwise by around an eighth of a turn; re-righten the Torx screw to lock it in, repeating as needed. Turning it the other way can reduce hesitation (stopping for a moment and then performing normally). Turning the flat-head screw one way increases the reaction time, the other way reduces it; the Torx screw locks the flat-head in place.

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