Performance Carbs & Race Carburetors

The carburetor is a simple mechanical device that works due to the Bernoulli principle.  It combines fuel and air before they are introduced into the engine through the intake valve.  Performance carbs are the most common type of carburetor sold for automotive applications, though smaller engine devices, such as chainsaws and lawn mowers, etc. still use carburetors.

The basic principle behind the carburetor, the Bernoulli principle, is fairly simple.  As the velocity of a fluid increases, pressure decreases.  This is exploited in the carb by directing air through the barrel, which has a tapered portion.  It's this portion where the jet is located, and the drop in pressure which regulates the amount of fuel coming from the jet.

That's a very broad overview, and to understand the entire process, you have to remember that the engine itself, due to the rotation of the pistons within, creates vacuum.  The intake of air is restricted to one point, at the carburetor.  Located at the end of the barrel, just before the air/fuel mixture enters the intake chamber, is a plate which is controlled by the action of the driver through the gas pedal.  When opened, the engine's vacuum allows air to enter into the engine through the carburetor barrel.

At some point in the barrel, there is a venturi, or a tapered section.  This is where the decrease in pressure happens.  Within the carburetor itself are chambers whose pressure is equal to atmospheric pressure.  Because there is a decrease in the amount of pressure at the venturi, which is where the jets are located, fuel is forced from the higher pressure chambers into the barrel at the point of lower pressure.

The carburetor was the standard method of fuel delivery until the late 1980's.  Due to decrease in price and increase in efficiency requirements, fuel injection became the predominant form of fuel deliver in today's automobiles.  What this means for the average consumer is that, though you can find replacement carbs for older model vehicles, the majority of carburetors that are produced today are performance carbs with speed and power in mind.

Through the years, what was defined as a performance carb has changed.  Today's performance carbs are usually four barrel with all the venturi measuring the same.  Previously, however, it was common to see varied barrel sizes, such as in the Quadrajet, which allowed for dual use.  Due to the action of either linkage or other means, the main jets were the first used and were intended for fuel efficiency and daily driving.  The secondaries would come into use under heavy acceleration and high speed use & these jets were tuned so that they delivered optimum performance from the engine at high speeds and heavy acceleration.

You can still find these multi-sized barrel configurations today for cars whose intended purpose is for both on and off track use.  For the performance minded engine builder, however, these do not provide any advantage and the use of a single sized barrel for each is the norm for drag and race cars.

Predator carburetors are manufactured by Predator in Lakewood, NJ. While the focus of Predator's carb design is on racing, their carburetors can also be used for street applications. The design of these carbs is for low-end response, which make them the ideal choice for many different applications, including drag racing, circle tracks, marine, show cars, etc.

The Predator 6000's varied four barrel design allows for an ideal air/fuel mixture at any speed. This design allows lower amounts of fuel to be mixed when traveling at lower speeds or when the throttle demand is not great. When the throttle is pulled wide open, this design automatically introduces more fuel into the mixture increasing performance at higher rpms.

Holley has been manufacturing caruretors for over 100 years. Their list of historical carbs include those used in Ford's Model A, numerous muscle cars throughout the years and over half the boats and airplanes used in WWII. Carburetors were not the first order of business for the company, which began building engines in the 1800's. It wasn't until asked by Henry Ford to build a carburetor for his vehicles that the company began to take the turn towards what they're best known for today.

Today, Holley carbs are used most often in racing and performance applications. They've produced both 2 and 4 barrel designs, with the 4-barrel carburetor being the most frequently used by engine builders today. You can find Holley's carburetor's on a variety of vehicles, including NASCAR cars and many high performance drag racers.

Manufactured by Barry Grant, the Demon carburetor is a series of carbs that sport some of the wildest designs available today. Their carbs are made for a variety of applications, but most visibly for old school restoration and hot-rodding applications. With designs that incorporate multiple two and four barrel carburetors, it's not hard to see why Demon carburetors are highly sought after.

One of the unique features of the Demon carb is the use of certified zinc in it's manufacture. Barry Grant cites this as a safety precaution, as use of substandard materials will result in possible corrosion and risk of fire and/or explosion.

Solex carburetors are a unique breed, with roots in France and production throughout the world.  Most notably, this design was used in European cars in the 1980s.  The list of manufacturers to include the Solex carb into their vehicle include Volkswagen, Alfa Romeo, Fiat, Audi, Ford, BMW, Citroen, Opel, Saab, Mercedes Benz, Volvo and Porsche.

Production of these carburetors has switched locations, from France to China and back again.  The original company was bought and sold several times and today is part of the Yamaha family under the MBK label.  In addition to this production, the "VeloSolex", a powered bicycle, is produced and owned by VeloSolex America, LLC.  This motorized bicycle incorporates one of the original Solex carb designs into its' engine.

DellOrto carburetors were originally produced starting in 1968 by the DellOrto company.  These carburetors were used in a variety of applications, most notably on motorcycles.  While their fame is most attributed to the use of DellOrtos on motorcycles, they did produce carbs for both industrial in automotive use as well.

Today you can find DellOrto carburetor parts and supplies from a variety of online merchants.  It's much more difficult to find orginial parts and carbs made by DellOrto, though they do exist, so many of the parts offered online are aftermarket reproductions.

Edelbrock carburetors are used for high performance applications where big power is produced by the engine.  They can be used in street cars, as they have several features that allow them to remain tuned without maintenance and prevent any damage to the carburetor due to backfire or the like.  For race and performance applications, they are very flexible, allowing multiple types of fuel to be used.  They also allow the engine tuner to make adjustments to the carb without the removal of the entire carb which makes them ideal for drag and racing cars where quick changes in the pits must be made.

Edelbrock offers two series of carbs, the Performer Series and the Thunder Series AVS.  Both come in a four barrel carb that have the same standard features:

• They work out of the box with no tuning or setup required other than installation.
• You can change jets, adjust the floats and change needles/seats without draining the fuel or removing the carb for easy tuning.
• Two piece design means that there are no gaskets below the fuel level, eliminating leaks.

JET Performance Carbs are racing tuned carbs in many different designs. While the company doesn't produce many of the carbs they offer, they do produce rebuild kits and other modification kits that allow you to tune the performance of your Holley, Quadrajet and marine carburetor.

Quick Fuel Carburetors, made by Quick Fuel Technology (QFT) are racing and performance carbs.  Founded in 1998, the company has grown to be one of the largest performance carb manufacturers in the last 12 years.  Originally began as a tuning company, QFT has developed and launched several lines of carburetors to become a stand-alone company.