Demon Fuel Systems RDA-650-MS Carburetor

Part Number
Road Demon Carburetor; 650 cfm; Mechanical Secondary; Down Leg Booster; Rated For 250-500 HP
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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. Available in 625 cfm and the new 525 cfm and 725 models; the Road Demon is perfect for small displacement V8 or V6 engines. The Road Demon 625 targets mild performance engines from 302 to 400 cid and rated at 250-350 horsepower. The new 525 Road Demon is for V6 engines and small V8s in the 260 to 400 cid range. The Road Demon 725 is perfect for stock V8 engines from 350 to 500 cubic inches. This makes them ideal for daily drivers as well as weekend cruising for a wide range of vehicles.

BRAND: Demon Fuel Systems


  • Holley Performance Emission Code 3: This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles and Racing Use Only Vehicles. The following vehicles are considered Uncontrolled (Non-Emissions Controlled) Vehicles: 1965 and older U.S. manufactured California Certified vehicles/1967 and older U.S. manufactured Federally Certified vehicles/1967 and older Foreign manufactured vehicle. The following vehicles are considered Racing Use Only Vehicles: Racing Use Only Vehicles are vehicles that are used exclusively for competition and that are not registered and that may never be used on the street. WARNING: It is against the law to install this part on an Emissions Controlled Vehicle. The following vehicles are considered Emissions Controlled Vehicles: 1966 and newer U.S. manufactured California Certified vehicles/1968 and newer U.S. manufactured Federally Certified vehicles/1968 and newer Foreign manufactured vehicle
  • Fuel Bowls Now Have Dual Threaded Inlets On Each Side
  • Secondary Fuel Bowls Include Notched Floats
  • Road Demon Carburetor
  • Changeable Power Valve Restrictions For Precise Tuning
  • Road Demon Carburetor; 650 cfm; Mechanical Secondary; Down Leg Booster; Rated For 250-500 HP;
  • Changeable Idle High Speed Air Bleeds
  • Redesigned Throttle Lever w/Integrated Kick Downs Options
  • With Billet Metering Blocks And Base Plates
  • 650 Road Demon-Mech Sec-Down-Leg ideal for daily driver or weekend cruising Designed for mild performance engines all sizes from 302 to 460 cid; and rated at 250–500 horsepower.
  • All Aluminum Polished Construction
  • Billet Baseplate Allows Precision Fine Tuning Of Idle Speed
  • Complete Reengineered and Re-Calibrated
  • Fuel Bowls and Main Body Have A Sleeker More Style Appearance


Billet ColorShiny
Booster TypeDown Leg
EmissionWithout EGR
FlangeSquare Bore
Fuel InletDual
Fuel System TypeCarbureted
Fuel TypeGasoline
High Speed Air Bleed31
Idle Air Bleed Size70
Primary Main Jet70
Primary Power Valve6.5
Primary Pump Nozzle Size31;31
Secondary Main Jet74
Secondary TypeMechanical
Supercharged ApplicationNo
Throttle Bore1.688 in.
UsageRacing/Circle Track
WARNING CA Proposition 65Yes
WARNING CA Proposition 65 MessageWARNING: Cancer and Reproductive Harm -


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