Naturally Aspirated – All Motor -1/4 Mile – .400 Pro Tree – 16 Car Qualified Field – Pro Ladder

Any questions or concerns, please email

Base Weights and Cubic Inch Limits:

  • Small Block Chevy, Ford, Mopar minimum weight 3000 pounds with a maximum Cubic Inch of 440.
  • Big Block Chevy, Ford, Mopar minimum weight 3300 pounds with a maximum Cubic Inch of 565.
  • Engine must be a corporate engine to corporate body match (i.e. – Ford/Ford, GM/GM, Mopar/Mopar)
  • Stock bore space blocks only – No billet blocks.
  • All Motors will be pumped (P/G) for compliance and sealed at indiscriminate times at any race.
  • Any time a seal is broken, engine will be required for re-pumped and reseal.
  • Any infraction (CHEATING) can or will result in immediate disqualification from series.

Cylinder Heads:

  • OEM STYLE means standard port and valve layout front to rear, and port height within reason of understanding what commercially is available for conventional heads. No billet heads. This definition will be subjective under MOTORCITY MUSCLE CHALLENGE tech discretion.
  • Big Block Chevy, Mopar, Ford Conventional OEM style heads. Minimum weight of 3300 pounds. No billet heads. No hybrid OEM Style racing heads. No SR20 style BBC heads, only normal conventional aftermarket heads such as those from Brodix, Dart, BMF, AFR, B1, Indy, TFS etc. allowed. No intake port height limitations.
  • Big Block Buick, Oldsmobile & Pontiac Conventional OEM style heads. No billet heads. No hybrid OEM Style racing heads. Tech will use discretion when considering legality of heads presented to advisory board.
  • Small Block Chevy, Mopar, Ford Conventional layout, in-line valve style heads. Minimum weight 3000 pounds. No port height limitations. Non inline cylinder heads such as SB2, Yates Style, may run with 75 lb. penalty. No billet heads.
  • LS Based Engines, in-line heads allowed at base weight. MAST STR8 Jacket and CID BE-LS inline heads add 75-lbs. Other similar style heads not specified here will be considered on a case-by-case basis. Canted and/or splayed valve heads such as Mast Mozez or Edelbrock LS-R heads, add 125-lbs. No billet heads.


  • Any commercially available 4150 style 4 bbl. single carburetor allowed. Little Bo’- Get’M Garage style 4150 carbs with twin blades are allowed.
  • Throttle Blades: TB 1200, Holley 4150, 1.75” Braswell 1.75”, Gary Williams D Blade 1.75”

Fuel Injection:

  • No fuel injection allowed.

Oiling Systems:

  • Wet or dry sump systems allowed.

Intake Manifolds:

  • Any commercial off the shelf (COTS) “out of the box, bolt on” cast aluminum intake manifold allowed. No external modifications, no custom, “one off” manufactured, no cast blank intake machined and modified to fit, no cutting and welding runners and/or mounting flanges, no re-drilling flange (bolt holes must remain as machined in COTS production) and manifolds must have manufacturer’s part number identification visible as provided by manufacturer when new.
  • Any design allowed but must fit under the hood.
  • No tunnel rams or bolt together style intake manifolds allowed – NO EXCEPTIONS! (This includes top to base or side to side).
  • No intake spacers of any kind allowed – intake must bolt directly to cylinder heads. (All reviewed at technical advisor’s discretion*)


  • Automatic Transmissions: Any auto trans allowed. Adapters are permitted. Trans brakes permitted. Automatic transmission entries run at listed base weights. Pneumatic, electric, hydraulic, etc. shifters prohibited. Any gear change must occur from direct action by the driver.
  • Manual Transmissions: Any style manual transmission allowed. No limits on clutch style. Add 75-lbs.


  • Stock steel fenders, steel doors, steel trunk lid. (Magnets will be present).
  • Stock located factory steel firewall and factory steel floor pan are required.
  • Factory appearing rear spoilers allowed. Rear Wings allowed.
  • Fiberglass bumpers allowed.
  • Fiberglass hoods allowed.
  • Pro Glass- Optic Armor type glass is permitted provided it is attached and installed (butyl, glue etc.) as OEM size and style glass with the OEM fashioned trim. No nuts, bolts, screws, rivets, etc., allowed.
  • Must appear as Factory or OEM by tech directors.


  • Limited to 6″ cowl style hood. (+/- ½”) No forward cut outs in hood permitted.
  • The 6-inch maximum means anywhere along the cowl scoop profile, measured against the primary surface of the hood.
  • No single point of the cowl allowed to be measure more than 6″.
  • No aftermarket forward facing hood scoops.
  • No restrictions on air intake position. i.e. under the car, grill area, windshield etc.


  • Factory frame rails required, front to back.
  • May be mini-tubbed with narrowed frame rails.
  • Modifications allowed for clearance only.

Rear Suspension:

  • Stock Leaf Spring or Stock Coil Suspension.
  • Coil over shocks allowed.
  • Traction Bars, Cal Tracs, Slide-a-Link or Torque Arms are permitted.
  • Ladder Bar.
  • Bolt in or weld in anti-roll bars allowed.
  • No 4-Links allowed.
  • Wheelie Bars Prohibited.

Front Suspension:

  • Front suspension must represent the “stock type” suspension for the model car being used. “Stock Type” refers to any custom parts used must mount directly to stock suspension points. Cars originally equipped with A-Arms must continue to use A-Arms on the stock mounting points. Aftermarket A-Arms which are adjustable are acceptable. Cars equipped with Struts, must utilize struts in the original strut towers. Manipulation for proper geometry within the tower is acceptable. Bolt on K-Member style cradles for late model cars are acceptable but must follow the Strut and A-Arm rules. Coil over front shocks allowed. No Spindle mount wheels.

Rear Tires:

  • Tires limited to 9×26, 9×28, 9×29, 9×29.5 or 9×30 slicks only. Radial sidewalls permitted.

Oil Retention Device:

  • Lower Engine Containment Device or Diaper Required
  • Diaper Device may be custom-built ballistic blanket-style (Diapers: They do not have to be SFI rated.)
  • Metal bucket device or metal pan may be no longer than the engine from the front of crankshaft to the rear of the flywheel.
  • Pan must be inside the frame rails and fabricated to retain oil\liquid.
  • Pan must attach to the frame via conventional fasteners or straps.
  • Pan must be a minimum of 3 inches above ground.

Any infraction (CHEATING) could potentially result in disqualification from series per rules board


*All Rules Are Subject to Change