Although a number of years have passed since a vehicle equipped with a carburetor has come off an assembly line, those venerable mixers invented by Karl Benz almost 150 years ago are still doing duty, many of them under the hoods of classic trucks.
And while it's true that today's sophisticated electronic fuel injection offers some advantages in efficiency and adds a purposeful look, the expense and complication of retrofitting such a system makes the simplicity and price point of carburetors hard to beat.
While all carburetors rely on the same principles to operate, there are noticeable differences in design. One of the most successful incarnations of the carburetor was the Carter AFB (aluminum four barrel) introduced in 1957. Found on a variety of engines from every major manufacturer, they gained a reputation for performance in the musclecar era when they were used on dual-quad equipped 409 Chevys and 426 Mopars; a pair of AFBs meant serious horsepower was on tap.
One of the oldest and most respected names in the performance business is Edelbrock; some time ago they began offering a carburetor with that famous family moniker. Basically a refined and updated version of the AFB, dubbed the Performer, these carburetors have a number of unique design features. There are no gaskets below the fuel level so if you leave your classic truck parked for extended periods you don't have to worry about leaks or gaskets drying out and not sealing when it's time to hit the road again. Another part of the design that makes these carburetors user-friendly is the enrichment system. Vacuum controlled metering rods can't blow out if the engine backfires and are easy to change for tuning purposes. Finally these carburetors have what are called velocity valves in the secondaries. These counterweighted flaps above the secondary throttle valves keep the engine from stumbling when the throttle pedal is mashed to the floor; they won't open until the airflow is sufficient enough to force them to do so.
Performers are available in 500-, 600-, 750-, and 800-cfm ratings, so finding one to fit the needs of any engine isn't a problem.
Despite the fact carburetors are relatively simple, they still require maintenance, adjustment, and possible tuning to deliver the performance and mileage they're capable of providing. But before tearing into the carburetor it's always wise to make sure everything else is in order. First and foremost, verify the engine in question is mechanically sound and do a compression or leak-down test if there is any doubt. Check the condition of the entire ignition system and set the timing. Lots of carburetors have been rebuilt or replaced when what the engine really needed was a good tune-up. Finally, spring for a new fuel filter, air cleaner element, and check the idle speed and mixture.
Generally speaking, carburetors don't just go out of tune. In other words, if the jetting was right to begin with, it won't suddenly become wrong. But if when installing a new carburetor, or if changes have been made to the engine, some adjustments may be in order.
Leroi "Tex" Smith has been fooling with carbs for years, but before you tear into one, mak
Eventually even the best of carburetors will need to be disassembled, cleaned, put back to
Performer carburetors have two separate float bowls. The primary jets (arrow 1) are betwee