Ask any Speedhunter from days gone by about early automotive modifications and they will be pleased to engage you with a sparkle in their eye. The first round of performance upgrades that befell popular sports and muscle cars of the ‘60s and ‘70s were for most a set of Hooker Headers, an Edelbrock intake, and a Holley carburetor. Performance intakes and carburetors were popular with the salt flats racers of the 1940s and the early hot rodding community of the 1950s, and their popularity lives on with gearheads today. Since Speedhunters has dedicated their January Theme to the black art of carburetion, we’re going to look at the history of carburetion from the company that has sold over 250,000,000 carburetors to date!
My name is Blane Burnett and through my work as the marketing and public relations coordinator for Holley, carburetors have become a vast part of my daily life over the past four years. Prior to Holley, my background was primarily in sport compact cars, so my knowledge of carburetors was extremely limited. I had grown up in the fuel injection era, appreciating anything automotive, but assuming carburetors only belonged on older cars. I’d never had the opportunity, nor had I taken the time, to understand all that Days of Thunder voodoo.
Over the years I’ve become enamored with both the automotive and lesser known aeronautical history surrounding the company. It is replete with famous products that have not only aided American soldiers on the battlefront, but were also an integral part of the hot rodding movement following WWII.
Though they might look confusing, carburetors are relatively simple creatures. Simply put, they are mechanical fuel metering devices which operate under the logical and straightforward laws of physics. Over the years they have evolved from relatively simplistic designs to the intricate carburetors offered today.
Three main types of carburetors have been used by OEM manufacturers throughout the course of carburetor history: updraft, sidedraft, and downdraft. Updraft carburetors are an early design that fell out of use in the 1930s and were primarily used in aviation. These carburetors offered good anti-flooding attributes needed in an engine living at high altitude. Gravity feeding fuel to updraft carburetors was also common in automobile applications. It allowed for the carburetor to be mounted lower than side or downdraft carburetors.
Sidedraft carburetors are typically used in inline or transverse mounted four and six cylinder applications. When mounted in an inline configuration, separate carbs for each cylinder benefit an engine as it allows each cylinder to maintain the proper intake runner length, freely drawing air through its own venturi, throttle plate, fuel line, etc. This is crucial in inline four and six cylinder applications because not all of the cylinders can breathe the same amount of air depending on the construction of the intake manifold. Intake runner lengths can also be tuned, and they look absolutely stunning. The Mikuni 2-barrel sidedrafts that replaced the single-barrel Hitachi S.U. carbs on Datsun’s Z-series cars and other performance oriented Japanese and European sportscars are great examples of quality sidedraft carburetors.
The story of the sidedraft carburetor began with a French company called Solex, a company that developed carburetors following World War I. Solex advanced the design of the sidedraft carburetor over the years, and their products were featured on numerous European models, from Italy’s Alfa Romeos to France’s Renaults and Peugeots.
Somewhere along 1960, the Mikuni carburetor company licensed the ability to produce Solex carburetors in Japan, eventually achieving what many think to be a superior carburetor to the original Solex in their 44mm and 50mm PHH line. While you won’t be able to find a brand new set of automotive Mikuni carburetors today (aside from the infrequent Craigslist or eBay ad), Mikuni does manufacture a full line of sidedraft carburetors for motorcycles and watercraft.
Another name that shouldn’t be left out is Eduardo Weber. In the years spanning 1920-1930, Weber, having experienced success in the passenger car market, confidently entered into the race market, building carburetors for Maseratis and Alfa Romeos. The company’s website reports that after WWI, Weber was responsible for releasing the first double-throat sidedraft carburetor to market.
Downdraft carburetors allow for the supply of copious amounts of air and fuel to the engine, as in high performance applications like drag racing or road racing. Most eight cylinder vehicles utilize a downdraft carburetor because the intake manifold and the carburetor can easily nestle between the two cylinder heads delivering air and fuel to each cylinder. Designing a single modular downdraft carburetor that was able to supply enough fuel and air to an engine cut down on the amount of carburetors required and became Holley’s default choice for carburetor design from the 1950s moving forward.
Holley carburetors have remained synonymous with the hot rodding community for decades and it has done so by releasing several carburetors that have become go-to products for extracting more performance out of their engines. Popular carburetors like the 4150 series, 4160 (specifically the 3310), Double Pumpers, and Dominator carburetors all changed the way hot-rodders, racers, and enthusiasts accomplish their goals. The 3310 carburetor (pictured above) powered the 425 horsepower version of the 1965 Chevelle and was later named one of the original 10 most influential speed parts of all time in Hot Rod magazine’s ‘Speed Parts Hall of Fame’.History Surrounding The Holley Carburetor
Holley’s story begins with George and Earl Holley, two teenage brothers from Bradford, Pennsylvania, who developed patterns and castings in order to build a one cylinder engine in the late 1800s.
One three wheeled vehicle capable of 30mph led to motorized bicycles, and then to this – the Holley ‘Motorette’. Fast-forward to 1903, and after meetings with Henry Ford, the two brothers formed the Holley Carburetor Company, producing carburetors for Ford Motor Company.
Business expanded throughout the years, most notably throughout WWI and WWII as Holley fulfilled military contracts producing fuel systems for Packard powered PT boats, variable venturii carburetors for DC-3 airplanes, as well as B-25 Mitchell aircraft. Almost half of the carburetors used in the two wars bore the Holley name. Following the country’s time at war, Holley directed their focus toward supplying fuel systems to automotive OEMs, along with supplying replacement parts to service stations and repair garages. The automobile was becoming increasingly popular to the American public during the ‘Golden Age’ of American history.
During that same time period of the 1940s’ carburetors like the Holley 94 and Stromberg 97 were gaining in popularity. Regardless of the type of vehicle, you can rest assured it was being turned into a hot rod by a group of kids somewhere. It was perfectly normal to see autos-turned-hot rod sporting multiple carb setups on Edelbrock manifolds from this time period onward before mechanical injection was developed. Even today, it is still common to see hot rods running old Flatheads that are traditionally adorned with Stromberg 97 carbs.
In the ’50s Holley developed the Holley Model 4150 4-barrel carburetor which debuted on the 1957 Ford Thunderbird. This was an incredibly important innovation in carburetor history as the 4150 design quickly became a mainstay in the world of performance motoring due to its simplified, modular design.
While the 1960s started a revolution of sex, drugs, and rock ’n roll, it was also the decade of the muscle car. Manufacturers like Chevrolet, Dodge, and Ford were releasing high horsepower versions of their muscle cars during this time, and while their base models came with carburetors like the Quadrajet, Carter AFB, or Thermoquad, Holley’s fuel system prowess was called upon to support the OEM factory beasts of the day. Z/28 Camaros, big block Chevelles, Boss Mustangs, and Shelby Cobras are just some of the vehicles that were factory equipped with Holley 4-barrel carburetors. Holley also collaborated with Chevrolet on their 1967-69 427 Tri-Power Corvettes and with Chrysler on their Six-Pack setups.
In 1968 Holley released the largest 4-barrel carburetor the company had designed for automotive use at the time. Developed in secret with Ford’s NASCAR program, this ‘mystery carb’ was sized at 1,050 CFM and was eventually christened the Dominator. Today Holley carburetors remain the carburetor of choice in numerous NASCAR racing classes with the exception of the Sprint Cup series, which made the switch to fuel injection in 2012.
The 1980s brought forth a number of changes in the world of carburetion. Edelbrock Corporation, who had previously focused on intake manifolds in their early years, broadened into a more diverse product line to include carburetors. While a good majority of OEM manufacturers were beginning to release vehicles with factory equipped fuel injection, carburetors continued to dominate in numerous forms of motorsport. Holley powered all of the winning NHRA Pro Stock racers and all NASCAR’s premiere Cup Series teams of the period.
Post millennium, carburetors have continued to evolve due to the wide range of motorsports in which they are used. While there are indeed numerous benefits to fuel injection, classic carbureted vehicles always retain a certain character or personality that is simply missing in modern day automobiles. While companies like Mikuni and Solex are no longer manufacturing the amazing sidedraft carburetors for automobiles that were available in decades past, companies like Demon, Edelbrock, Holley, and Quick Fuel and others continue to keep the carburetor market alive with ever improving products.Modern Day Carburetion, Not An Oxymoron After All
Looking back in time at the progression of various carburetor designs will show a great deal of change in the way that air and fuel is blended together before entering the combustion chamber of an engine. Some looked very odd in their design (i.e. Holley’s Teapot carburetor), some were more efficient than others (the O.E. carbs produced during the ’70s during O.P.E.C. and emissions crackdowns), and some allowed enthusiasts to generate major horsepower, like the Dominator carburetors used in both NASCAR and NHRA.
Despite 4-barrel carburetors looking virtually the same for decades, they have evolved in various ways. As internal combustion engine and cylinder head technology has improved, engine builders have developed larger displacement engines that require different calibrations in order to ensure proper air/fuel delivery across the rev range of an engine. This has resulted in a need for larger CFM carburetors like Holley’s Gen 3 Ultra XP Dominator carburetor (above), which is sized at 1475 CFM, 425 CFM more than when the original Dominator was released!
Beyond that, modern day fuels are pure evil for vehicles that sit for extended periods of time, whether they are carbureted or fuel injected. Corrosion resistant coatings found on present day carbs combat higher ethanol content and general changes in the chemical composition of gasoline that can often wreak havoc on fuel systems of many classic and performance vehicles. Overcoming these hurdles is critical when developing fuel system components that are produced to work with 21st century gasoline. Regardless of the type of carburetor in question (Holley, Weber, Mikuni, Solex, etc…), it is imperative to make sure that carburetors are used regularly or stored properly if expected to perform at their best.
The type of materials used to produce carburetors has also improved over time. Check out an example of a modern day carburetor. This is Holley’s Ultra XP 4-barrel 4150 carb. Compared to traditional zinc carburetors of the past, the XP features lighter components, utilizing a billet aluminum base plate and metering blocks. Lowering weight on top of an engine reduces weight in a critical area. Furthermore, the fuel bowls have an added shelf cast into them which aid in decreasing fuel slosh. The carb also withstands the damaging effects of the fuel that we are blessed with today through the application of Holley’s proprietary ‘Hardcore Gray’ hard coat anodizing process. The list goes on as this carburetor boasts a plethora of features that were previously only available after purchasing a carburetor and then spending additional money to send it to a carb modifier to have similar services provided.
While carburetors no longer come as standard equipment on automobiles, they certainly have a clear place in the world of classic and performance vehicles today. Enthusiasts have a knack for restoring and modifying older vehicles and carburetors continue to offer a more cost effective performance solution to more expensive fuel injection systems. Many racing organizations still mandate the use of carburetors in their various classes, from amateur circle track racing all the way to vintage drag and road racing. Where there are gearheads there will always be development to improve upon the age-old design of the carburetor, offering more tune-ability and performance to the engines of today.