Making An Edelbrock Carb Work Better For Off-Road Applications


Edelbrock is a household name today in the automotive world. However, when Vic Edelbrock Sr. started building hot rods after establishing himself as an expert mechanic through years of working in his own automotive repair shop, first on Wilshire Boulevard in Beverly Hills in the 1930s, and then in Los Angeles on the corner of Venice and Hoover, not many realized just what magic the mind of this genius would produce over the decades.

First came Vic Jr., his only son, then came Vic Sr.’s first project car, a 1932 Ford Roadster. The “Slingshot,” his own design for an aluminum intake manifold, was the first of many products to come that would bear the “Edelbrock” name. That Roadster was his first test bed, and was used to develop and determine how well new products performed.


Early model rigs such as this Blazer are perfect candidates for new Performer and Thunder AVS carburetors, especially when modified for improved off-road performance.

That same inventive fever was passed down to Vic Jr., who heads up the company today. The Edelbrock Corporation now has six locations, three in Torrance and two in San Jacinto, California, as well as another in Sanford, North Carolina. The San Jacinto locations include the company’s own heat treating facility and a casting foundry that are part of Edelbrock’s “Made in USA” commitment.

We visited the Torrance facilities to take a tour and get the full story on Edelbrock’s Performer Series and Thunder AVS Series carburetors as well as learn how to convert a Performer Series carburetor so it will work better in off-road driving conditions. We not only learned about some of the differences between these two popular Edelbrock carburetors, but were impressed by the manufacturing, design, and R&D facilities we inspected.

The Performer Series

The Edelbrock Performer Series are well-built carburetors designed to handle years of daily driving, and deliver consistent performance. There are a number of characteristics that make this series of carburetors an outstanding choice for the truck owner, and is designed to be user-friendly.

With throttle link, trans cable or carb adapter kits, the Performer can be used on almost any vehicle – Smitty Smith, Edelbrock.

The Performers use metering rods to transition between circuits, and are unaffected by engine backfires, so there are no power valves to blow out. The Performer is easily tuned; the rods can be changed in seconds, without having to remove the carburetor from the engine or drain the fuel.

The carburetors are also known for their ability to “hold a tune,” and maintain performance and calibration consistency over time. Simple bowls shaped like tubs, and rear-pivot floats make for a reliable carburetor. The Edelbrock carburetors lightweight aluminum two-piece body is designed to resist warping, and it will work with gasohol and blended fuels.


Edelbrock carburetors are known for their easy tuning, performance consistency, and wide variety of applications.

“The Performer is our most popular, and is available in seven models ranging from 500 to 800 CFM, in manual or electric choke design. With throttle link, trans cable, or carb adapter kits, the Performer can be used on almost any vehicle,” said Smitty Smith of Edelbrock.

Thunder Series AVS

The secondaries can be adjusted to open up later to help acceleration. – Smitty Smith

A jump up from the Edelbrock Performer Series is the Thunder Series AVS carburetors. These carburetors are designed and calibrated for the next level of performance, and are also available for a multitude of applications.

Primary, as well as secondary boosters deliver incredibly accurate calibration. The secondary circuit in the Thunder Series AVS carburetor can be quickly and easily adjusted using nothing more than simple hand tools, and you never have to remove the carburetor from your vehicle.


Thunder AVS Series carburetors (seen in this photo) feature spring-loaded secondaries that are adjustable, unlike the Performer’s counter-weighted secondary valves that rely on air velocity alone to open them.

Four models of the Thunder Series AVS are available (in both manual or electric choke design) ranging from 500 to 800 CFM; and one of then, a 650 CFM model, is designed and calibrated specifically for off-road performance. The Thunder Series AVS carburetors have applications for small-block and some big-block engines.

The off-road specific 650 CFM (1826, electric choke; 1825, manual choke) Thunder Series AVS carburetor can be matched with a variety of Edelbrock manifolds such as the Edelbrock Performer, Performer EPS or Performer RPM, or some other brands with similar designs. It includes spring-loaded needles and seats that can deliver better fuel control under off-road driving conditions.

What’s The Diff?

Smith explained, “The main differences between the Performer Series and the Thunder Series AVS is that the Thunder features spring-loaded secondaries that are adjustable. Performers have counter-weighted secondaries that are completely dependent upon air velocity through the carburetor to open the secondaries.”


There are two 650 cfm models in the Thunder AVS Series, the 1825 manual choke (left) and 1826 electric choke (right), that are pre-calibrated specifically for off-road use.

“The Thunder Series AVS carburetors’ spring-loaded secondaries can be adjusted to compensate for having the carburetor mounted on a heavier or a lighter vehicle,” Smith said. “The secondaries can act like a timing feature to open up later to help acceleration.”

Smitty told us, “There is also a 650 CFM off-road specific model in the Thunder Series AVS carburetor line accented in black that offers an exclusive factory standard feature. It comes with our Number 1465 off-road spring loaded needles and seats pre-installed for superior fuel control off-road.”

That is great if you’re in the market for a brand new carburetor, but what if you have a Performer Series or one of the Thunder Series AVS carburetors other than the 1825 or 1826 models and want to modify it for off-road use? Well, according to Smitty, you can easily do that with some Edelbrock parts, and you don’t have to remove the carburetor from the engine.

Make The Swap


We decided to convert the Performer 1406, as it is the most popular of Edelbrock’s automotive carburetors. The first step was to remove the eight T25 Torx-head screws on the top half.

Smitty showed us how in the Edelbrock lab, and it was pretty easy. However, you can just as easily perform this changeover in your garage while the carburetor is still on the engine with the hood of your truck up.

We began the operation with a Number 1406 electric choke Edelbrock Performer Series carburetor, one of the most popular Edelbrock carburetors the company offers, and a unit found on thousands of vehicles. We began by removing all the linkage fasteners, commonly referred to in many professional shops and home garages as “Jesus clips.”

Next, we removed the eight TORX head screws from the top half of the Performer Series carburetor body using a T25 driver. Once the top half was removed, we had access to the floats. We pulled the float retaining pins out and removed the floats to gain access to the stock needles and seats in the 1406 carburetor.

We then separated the two halves, and turned the airhorn over to reveal the floats. Then we removed the floats from their hinges and removed the old needles and seats.

Once the old needles and seats were removed, we replaced them with the set of new Number 1465 off-road spring-loaded needles. The new spring-loaded needles act like a shock absorber, reducing the chance that the carburetor’s fuel bowls will become flooded during off-road driving when the vehicle is likely to be bouncing around on uneven terrain, climbing, descending, or off-camber.

Then, we replaced the floats and retaining pins. The next step was to adjust the floats to compensate for the new off-road spring-loaded needles and seats. Be careful to NOT press the needles into the seats when adjusting the floats.

The new spring-loaded off-road needle and seat set is at left. The spring-loaded needle was assembled, and then placed into the new seat already in the airhorn.

Smitty taught us a few tricks that can help you in this reassembly process. The first one is that during the first float readjustment procedure a 7/16-inch drill bit comes in handy and a quick and easy measuring tool. The job is simpler if you turn the top half (or airhorn cover) of the carburetor upside down to perform this operation.

We bent the float lever along its flat spot just before the curve where it’s attached to the float. It doesn’t need to be bent much; just enough to create a 7/16-inch gap when the float rests on the needle. This is where that 7/16-inch drill bit comes in handy; the drill bit can be placed between the top of the outer end of the float and the gasket of the airhorn to judge when the gap is just right.

Then we moved to the two float readjustments. The first can be most easily done using a 7/16-inch drill bit as a quick gap-measuring tool. One of Smitty's helpful reassembly tips was to remove the metering rods prior to replacing the airhorn; it's much easier to put them back in after it's replaced, and damaging them during reassembly is less likely. Reattaching the airhorn of the carburetor was done by carefully replacing the eight T25 Torx-head screws.

Next we moved to readjusting the float drop. This was done with the top half of the 1406 carburetor in the upright position. The small tab that protrudes from the opposite side of the float pivot was bent ever so carefully until the float drop measured in the range of 15/16-inch to one-inch from the gasket.

Now we were ready to reassemble the two halves of the Edelbrock Performer 1406 carburetor with its newly installed Number 1465 off-road spring-loaded needles and seats, and readjusted floats. Smitty also gave us some advice here, “Take the metering rods out before reassembling the top, otherwise the rods are not easy to get into the jets, and you run the risk of bending the rods.”


One last tip for easy carburetor work Smitty handed down was a tool suggestion. One of his favorites is the Lisle 46500 Carb Pin Tool for replacing those hard-to-handle “Jesus clips.”

One More Tip

The top of the Edelbrock Performer Series 1406 went back on easily enough using the T25 driver to thread in the eight TORX head bolts, and we returned the metering rods to their proper locations. We then received one last tip from Smitty before we said goodbye. He recommended a tool he found years ago, “One of the best carburetor service tools you’ll ever use, the Lisle 46500 Carb Pin Tool is great for putting on those ‘Jesus clips’,” Smitty said.

With that we called it a wrap, packed our kit, shook hands, and were on our way. We learned a lot about what are without a doubt two of the most popular automotive carburetor series’ that day. We also learned how simple it was to make one of Edelbrock’s Performer Series carburetors more suitable for use in off-road driving situations.


Edelbrock offers adapters to fit its carburetors to different manifolds, and spacers for more plenum volume or greater carb-to-plenum floor distance to enhance torque and throttle response.

We also got a much better understanding of the history and present-day status of the Edelbrock company. If you’re looking for more information on the Performer Series or Thunder Series AVS carburetors, carburetor accessories, or other Edelbrock automotive products such as EFI systems, intake manifolds, superchargers, camshafts, cylinder heads, or any of the dozens of performance enhancing equipment it manufactures or sells, check out its website or call (800) 416-8628.

Among the many applications perfect for Edelbrock Performer and especially Thunder AVS Series carburetors are vehicles such as the classic Jeep Cherokee SJ and first-generation Ford Bronco.

About the author

Stuart Bourdon

A passion for anything automotive (especially off-road vehicles), camping, and photography led to a life exploring the mountains and deserts of the Southwest and Baja, and a career in automotive, outdoor, and RV journalism.
Read My Articles

Everything Off Road in your inbox.

Build your own custom newsletter with the content you love from Off Road Xtreme, directly to your inbox, absolutely FREE!

Free WordPress Themes

We will safeguard your e-mail and only send content you request.

Off Road Xtreme - The Off Road Magazine


We'll send you the most exciting Off Road articles, news, truck features, and videos every week.

Off Road Xtreme - The Off Road Magazine


We will safeguard your e-mail and only send content you request.

Off Road Xtreme - The Off Road Magazine


Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

Diesel Army
Diesel Army
Street Muscle Mag
Hot Rods & Muscle Cars
Engine Labs
Engine Tech

Off Road Xtreme - The Off Road Magazine

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

  • dieselarmy Diesel Army
  • streetmusclemag Hot Rods & Muscle Cars
  • enginelabs Engine Tech

Off Road Xtreme - The Off Road Magazine


Thank you for your subscription.

Thank you for your subscription.

Off Road Xtreme - The Off Road Magazine

Thank you for your subscription.

Thank you for your subscription.