2/14/2012 - Tech Articles

Closer Look: The New Demon Carburetion

The original Demon carbs revolutionized fuel delivery with a trend-setting design. But inconsistent quality and old-style manufacturing techniques led to quirky, often difficult to tune carburetors. However, a new carburetor rose from the ashes, blessed with new management and engineering teams, modern manufacturing procedures, dependable quality, and ready-to-go tuning right out of the box.

The transformation to modern performance and reliability was completed at the beginning of 2012. Today’s Demon carbs are produced to a much higher standard than before—to the OEM-style ISO 9001:2008 benchmark to be exact. The new Demon Carburetion made huge investments in updated tooling, state-of-the-art manufacturing processes, product improvements, and in a team of engineers, builders, technicians, and representatives committed to delivering the highest quality products and exceptional customer service.

We’ve seen these new carburetors up close and we’re very impressed with them. All models benefit from uniquely contoured throttle entries and smooth, concentric venturi bores (no more ridge lines to obstruct airflow!) for improved power output without sacrificing everyday drivability. Plus, every made-in-the USA Demon carb is wet-flow tested and packed with features like Max-Density™ cast metering blocks (Road Demon) or CNC-machined metering blocks with precision-drilled idle-feed restrictors and emulsion bleeds (Speed/Mighty Demon), high-flow fuel bowls with greater fuel capacity, non-discolorable sight-glass windows, 4-corner idle circuitry, power valve blowout protection, and a silver dichromate finish. Speed and Mighty Demon carbs also benefit from the exclusive Idle-Eze™ base plate, an ingenious device that allows quick and easy idle speed adjustment.

Demon engineers took these features and packed them into three distinct models—Street: Road Demon, Street/Strip: Speed Demon, and Race: Mighty Demon. When used as recommended, enthusiasts will be rewarded with increased performance, clean idle quality, and instant off-the-line response.

Road Demon
If you’re looking to wake up the dark side of a daily-driven hot rod or mild weekend cruiser, bolt up a Road Demon carburetor. These carbs have quick-change vacuum secondaries, a reinforced Max Density™ baseplate that resists ear breakage, down leg boosters, an electric choke, an integral automatic transmission kick-down mechanism, and a fuel feed line for easy installation. The vacuum-operated secondary throttle plates are ideally suited to engines coupled to automatic transmissions and stock to mild stall torque converters.

Road Demon carbs are calibrated for use on stock and lightly-modified six-cylinder and V8 engines producing up to 350 horsepower, with cam durations up to 220° (@ .050"). The Road Demon 625 is for engines ranging from 250 to 350 cubic inches; the Road Demon 725 is designed for engines displacing 350 to 500 cubic inches.

Speed Demon
The Speed Demon’s race-inspired design is ideal for musclecars, street machines, hot rods, and towing rigs with cam durations of 220-240° (@ .050"), producing up to 500 horsepower. They have down leg boosters, your choice of vacuum or mechanical secondaries, and an integral automatic transmission kick-down mechanism.

One Speed Demon feature that deserves extra attention is the billet aluminum Idle-Eze™ baseplate. It includes a specially designed air valve that allows you to fine-tune the idle speed by metering additional air into the intake manifold—avoiding the potential for stumble or reduced throttle response as engine rpms climb. The valve can easily be accessed through the air cleaner stud hole, and idle speed changes can be made quickly and accurately using a single screwdriver—perfect for engines with aggressive cam profiles.

Just like the Road Demon, vacuum secondary Speed Demon carbs are best suited for automatic transmission-equipped vehicles with low stall speed converters. Speed Demons with mechanical secondaries are for manual and automatic transmission-equipped vehicles with high stall torque converters operating at 2,500 rpm and higher.

The Speed Demon 650 is recommended for mildly modified engines displacing 302 to 427 cubic inches, and the Speed Demon 750 works exceptionally well on mildly tuned 427 to 477 c.i.d. engines. The Speed Demon 850 is well suited for use on mild performance big-block crate engines ranging in displacement from 488 to 540 cubic inches.

Mighty Demon
When a conventional carb can’t keep up, it’s time to step up to the biggest, baddest Demon of them all. For unrestricted airflow, Mighty Demon carbs have no choke horn. They also have replaceable air bleeds and idle feed restrictors, mechanical secondaries, and an Idle-Eze billet aluminum baseplate.

The Mighty Demon’s ready-to-run competition tune is perfect for high-compression engines with performance cylinder heads, a high-flow intake manifold, and extreme cam duration (up to 260° @ .050"). Choose the Mighty Demon 750 for a well-prepared 350 to 406 or a mild performance 427 to 468 c.i.d. engine. You’ll want the Mighty Demon 850 if you’re running a well-prepared, high output 440 to 540 cubic inch street or race engine.

There you have it—three new, high quality Demon carburetors. Add it all up and putting a Demon Carburetion Road Demon, Speed Demon, or Mighty Demon carburetor on your car is one of the smartest moves you can make to dramatically improve performance and drivability.

Parts List

Road Demon
DEM-4282010VE: Road Demon 625 cfm, vacuum secondaries
DEM-4402020VE: Road Demon 725 cfm, vacuum secondaries

Speed Demon
DEM-1282010: Speed Demon 650 cfm, mechanical secondaries
DEM-1402010: Speed Demon 750 cfm, mechanical secondaries
DEM-1563010: Speed Demon 850 cfm, mechanical secondaries
DEM-1282010VE: Speed Demon 650 cfm, vacuum secondaries
DEM-1402010VE: Speed Demon 750 cfm, vacuum secondaries
DEM-1563010VE: Speed Demon 850 cfm, vacuum secondaries

Mighty Demon
DEM-5402010GC: Mighty Demon 750 cfm, downleg boosters, mechanical secondaries
DEM-5402020GC: Mighty Demon 750 cfm, annular boosters, mechanical secondaries
DEM-5563010GC: Mighty Demon 850 cfm, downleg boosters, mechanical secondaries