Made famous in Mopar musclecar...
Made famous in Mopar musclecar applications, this brand-new AVS carb is something nobody expected to see in 2003. Edelbrock's Thunder Series AVS is conceptually similar to the OE design but has strong similarities to their AFB-derived Performer Series carbs.
The AVS carb has special significance to Mopar enthusiasts. Standard equipment on such legendary performance mills as the 340 and 440 Magnums and Commandos and most high-performance 383s, the AVS is a proven design. What makes it so good? Before the AVS came along, the AFB was the four-barrel of choice. The design used a counterweighted air valve under the venturi to dampen the transition from primary to secondary operation. This system was effective but lacked a provision for adjustment. The AVS design moved the air valve to a position above the fuel-discharge port, and some good things came as a result. The AVS air door did away with a fixed counterweight, making spring tension necessary for action. With a wound spring, the air door could be easily adjusted for opening rate, allowing infinite tunability.
If the advantage ended there, it would have been a worthwhile change, but the position of the air door added another dynamic. With the air door above the fuel-discharge nozzles, it created a pressure drop at the fuel-discharge point, making for a faster reacting carburetor-another point for the AVS. AVS production as an OE carb came to a halt by 1972, and for all these decades we've mourned its passing.
For years, Edelbrock has been heavily involved in the carburetor market, deriving a new product from the AFB design. Now, the crew has recognized the potential of the AVS concept, and, for the last few years, quietly developed a modern version of the AVS, recently released as the Thunder Series AVS. This carb is unique in that it's conceptually similar to the traditional AVS, while sharing many of the components and tuning parts with the successful AFB-derived Performer Series carb. The Thunder Series carb incorporates a top-located air valve but retains the traditional venturi in the secondary barrels. Edelbrock's goal was throttle response and tunability and a maximum level of parts interchangeability with their existing carb design. For a closer look, we got our paws on one of the first units of production carbs. We decided to bolt one on to see how well it operates in a typical street performance application, and we liked what we found.
 The key feature of the new...  The key feature of the new Edelbrock AVS is an adjustable secondary air door at the top of the secondary barrels. The air door prevents a bog as the mechanical-secondary throttles snap open. Note the conventional venturi and booster venturi in the secondaries. |  From the top, the new Thunder...  From the top, the new Thunder Series AVS (right) is virtually identical to the Performer Series carb (left) on the primary side, while the secondary air door clearly differentiates the backside. Below the air door, the venturi arrangement of the Edelbrock AVS is identical. Tuning parts interchange. |  In contrast, the original...  In contrast, the original AVS used simple spray bars to discharge fuel and bores without venturis on the secondary side. |
 Adjusting the tension on the...  Adjusting the tension on the air door is simple and requires no disassembly of the carb. Just loosen the Torx-head lock screw, and adjust the spring shaft with a flat-head screwdriver. |  The Thunder Series AVS isn't...  The Thunder Series AVS isn't a resto reproduction of the original carb, but an all-new design that utilizes the advantages of the air-valve concept. |  Edelbrock's AVS is drilled...  Edelbrock's AVS is drilled for a fuel inlet at each side of the carb, allowing it to be plumbed from either side. It is shipped with a plug on the linkage side, but a dual inlet system can be purchased as an accessory. |
 To get a feel for the carb's...  To get a feel for the carb's manners on the street, we wanted to bolt on a fresh AVS for an unscientific road test. We happened to have a Dart with a warmed-over 340 sporting an Edelbrock Air-Gap intake. |  The package from Edelbrock...  The package from Edelbrock comes with the required vacuum plugs and gaskets for a basic installation. |  A barbed hose fitting is connected...  A barbed hose fitting is connected to the fuel inlet. If you would rather run a flared hard line, the flared inlet fitting from a stock Carter AFB, AVS, or ThermoQuad carburetor can replace the barbed fuel-inlet fitting. |