Engine Out: The Allure of Weber Carburetors

December 6, 2021

Engine Out is a new feature about the backstories of suppliers and components that are critical to our hobby. As an entrepreneur, I’m fascinated by how these companies got started. These stories less “shop manual,” and more “history book.” Being less technical, I’ll do my best to describe the mechanical side. Please let me know if I get it wrong, or if I've overlooked anything important. If you have a suggestion for a supplier to cover, please let me know!


The allure of the Weber carburetor is palpable. Just utter “Webers” and it evokes excellence, power, quality, and a long history that intertwines with many of the greatest cars and brands. In most configurations, they sit front-and-center on top of the engine. In their best presentation, the row of trumpets look like some sort of insane musical instrument. 

No other component even comes close in terms of name recognition and fandom, at least in European cars. I recently found myself getting sucked into the vortex (or should I say venturis?) of Webers, so I set out to discover for myself exactly what makes something as humble as a carburetor so desirable. 

The Weber Origin Story

In spite of the German sounding name, Weber is a purely Italian story. It is named after its founder Edoardo Weber, whose father was Swiss German. Edoardo, born in 1889 in Torino, came from a family with a passion for mechanical things. Upon graduation from technical college, he joined FIAT in 1907, right as the automobile age was starting to hit its stride. He worked his way up the company ladder and in 1912, at age 23, was promoted to foreman of FIAT's Bologna office.

Edoardo Weber

Following WWI, he returned to Bologna. In 1920, he founded Fabbrica Italiana Carburatori Weber, or Italian Factory Weber Carburetors. Its initial success stemmed from a conversion kit that enabled trucks to run on kerosene since gasoline prices had skyrocketed after the war. 

Weber Carbueretor’s breakthrough came in 1925 when they produced conversion kits for FIAT cars called the “Econo Supercharger” carburetor, it introduced Weber’s key innovation: the two-stage carburetor. (More on that later.) The benefit was that this set-up would provide good efficiency at lower speeds and better performance when needed. 

E. Weber (L) and E. Ferrari (R), 1933.

From street cars, race cars quickly followed, as Edoardo had dabbled in racing himself.  Race applications only required the larger sized barrels and were configured so that each cylinder had a dedicated barrel. Weber later developed dual float bowls to prevent fuel starvation during hard cornering. They became standard issue on the great Italian race engines of the day coming out of Alfa Romeo, with the team being run by the infamous Enzo Ferrari, as well as by Maserati. 

Weber’s notoriety grew, and their carburetors became standard issue on nearly all cars produced in Italy, including FIAT. The mass production required a large, modern factory, which was built on Via Timavo and opened in 1940.

Weber Carburetor's factory was used to support the war effort in WWII. It was spared bombing by the allies. However, Edoardo was not so lucky. It just so happens he wasn’t a little fascist, he was a lot. When the war concluded, the partisans had a reckoning. There is no official record of his death, but it is widely assumed that he was executed by partisans when he was on a daily walk in May 1945. 

FIAT took control of the company in 1952. Weber carburetors' popularity grew beyond Italy, and eventually they were used in Aston-Martins, BMWs, Porsches, Renaults, and Volkswagens, with conversion kits available for many other marques because they improved performance and were easy to tune. 

The Weber Carbs Difference

DCOE Accelerator Circuit

Two-stage. Carburetors had been around since the 1820s, but Weber’s ingenuity lay in its unique two-stage, carburetors. Weber pioneered the use of two venturis, a smaller one for low-speed driving, and a larger one for high speeds. Up to that point, it was one-size-fits-all and you got what you got, but Webers let you “have your cake and eat it too.”

When the Weber throttle is closed, a small jet (idle) feeds a minimal amount of fuel into the system to match the restricted airflow. From there, several other “circuits” open progressively while cruising up to “wide open throttle” at full acceleration (shown right). 

One Barrel per Cylinder. Although not always configured in this way, Weber carburetors are designed to be “one carburetor per cylinder.” It ensures the most direct way to get the fuel into the piston and maximized air flow. Generally, Webers are two-barrel units, and are designed to be connected sequentially, e.g. three carbs on a 6-cylinder engine or six on a 12-cylinder.

Dual floats. Developed for racing where high Gs in cornering can prevent fuel from entering the carburetor, Weber made this design to keep the fuel flowing regardless of the lateral Gs.

Straightforward Mechanics. A significant and driving factor in the popularity of Webers is their mechanical simplicity. Sure, there’s some artistry to getting them optimized, but they can be installed and repaired by amateurs. The primary moving part is a spring-loaded butterfly valve that opens as the throttle is pressed, while the tuning comes from adjusting screws to get the proper calibration for fuel mixture. 

Configurable, Lightweight Designs. Webers come in many different models but all are made of lightweight alloys that fit engines of nearly every size. There are downdraught and sidedraught models. They typically come in two-barrel models, although single-barrels are also available.

Weber Carburetors Today

They are as popular as ever, although fuel injection has now made them specialty items for classic car owners and performance tuners. New carburetors are being produced in Spain, but the original carburetors are highly valued. Since they are easily refurbished, they can be acquired from private owners or collector parts suppliers. 

Weber has changed ownership over the years. Under FIAT’s ownership, it was brought under the umbrella of Magneti Marelli, a huge Italian conglomerate that provided many automotive components. In 2019, Magneti Marelli was split off and then merged with Japanese auto parts manufacturer Calsonic Kansei. The joint entity still bears the name Marelli. 

Got more to add to the story? Please reach out to me.

References:

History and Origin of Weber Carburetors (citing BitsofItaly.com and Hemmings Classic)

Heideman, Carl, SU or Weber Carburetors?, Classic Motorsports, 25 November 2021

Weber DCOE Carburetor Reference: Theory, Configuration, Tuning, Modifications, & Reference Documents

Woodford, Chris, Explain That Stuff: Carburetors, 2 February 2021

Types of Carburetors (Automobile), What-When-How

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