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Speedway Motors Bill Smith

Road Demon 4282010VE 625 CFM 4 Barrel Carburetor

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Styled and calibrated for Street Rods and mildly modified Street Machines and light trucks, the Road Demon™ is an impressive performer. With a remarkably smooth choke tower design, vacuum secondaries and patented air entries, the Road Demon™ offers extremely smooth operation with strong throttle response. The Road Demon™ has the standard Demon carburetor features: Max–Density Cast metering–blocks with adjustable jets and four–corner idle, a billet baseplate, plus large capacity fuel bowls with patented sight glasses for tuning ease.

Perfect for small displacement V8s or V6 engines, the Road Demon™ 625 targets mild performance engines from 302 to 400 cid, and rated at 250–350 horsepower. An ideal carb for daily drivers as well as weekend cruising for a wide range of vehicles.

  • Max-Density Cast Rib-Reinforced Baseplate
  • Max-Density Cast Metering Blocks
  • Four-Corner Idle Circuitry
  • Large Capacity Float Bowls
  • Large Glass Float-Level Sight Windows
  • Integral Hi-Flow Choke Housing
  • Electric Choke Included
  • Dual-feed Inlet
  • Vacuum Secondary Operation
  • Power Valve Backfire Protection
  • "Quik Release" Non-Stick Gaskets
  • Vacuum Fittings
  • Most common tuning parts interchange from other manufacturers (jets, power valves, gaskets, etc.)
  • Quick-change Vacuum-Secondary Spring Cover 

Road Demon 4 Barrel Carburetor Installation Instructions (PDF) 

Application

We recommend the Road Demon 625 for Mild Performance and Towing applications with 302-400 c.i. V-8 engines.

Works great with camshafts under 220° duration @ .050". 

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Speed Demon 650 CFM 4 Barrel Carburetor Installation (PDF) 

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The Speed Demon series is the most formidable performance street carburetor available today. It features the most advanced design manufacturing processes that provides street enthusiasts with racing carburetor technology in a very driveable package. The Speed Demons delivers balanced, high–velocity airflow and exceptional fuel metering capacity to match the fuel requirements most street engines.

A Speed Demon carburetor is ideal for muscle cars, stock rebuilds, tow trucks, mild performance applications and crate motors. They are designed for engines with cam profiles between 220 and 240 degrees duration at 0.050". Designed for Mild 302 to 427 cid engines.

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  • Billet Metering Blocks
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  • Four-Corner Idle Circuitry
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  • Large Glass Float-Level Sight Windows
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  • Integral Hi-Flow Choke Tower Housing
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Speed Demon 4 Barrel Carb Installation Instructions (PDF) 

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The Holley Street Avenger Model 4150 four barrel carb is the ultimate vacuum secondary street performance upgrade. This 4 barrel carb is street ready right out of the box and features a calibrated electric choke, air and fuel adjustments and built in fuel filters. There are clear sights for easy float adjustments, adjustable vacuum secondaries and four vacuum ports. Plus it has a million mile power valve, is 100% wet flow tested and includes fittings.

  • No Trouble quick change vacuum secondaries - up to 6% more acceleration or 5% better fuel economy with simple spring change (springs included) 
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For Road Demon vacuum secondary carburetors.

910-12045 Instructions (PDF) 

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  • Eliminate fittings and adapters, with 3/8" hose barb
  • Center to center:  9-5/8"
  • Hose outlet nipple:  3/8"
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