Big Block Modified Rules


Safety Rules:

•  Safety is the First Priority. If You Do Not Pass the Safety Tech-In, You DO NOT RACE. ALL SAFETY RULES Apply - See GENERAL RULES.

•  Must Have Window Net on Drivers Side.

•  Must Have Rear Drive Shaft Loop.

•  Must Have Secure Roll Cage, Harness, Helmet & Fire Extinquisher

•  On/Off Battery Disconnect Switch is Required at the Rear on the Passenger Side. The Switch must be Located a Minimum of Twelve (12) Inches to a Maximum of Twenty-Four (24) Inches from the Side and a Maximum of Twelve (12) Inches from the Rear.

Weight: This is a Weight Limit Class. Your Truck must weigh 8 lbs per cubic inch with driver in truck.

Roll Cage:

1. Must Have a 4-Point Roll Cage in the Cab Welded to Frame. A 6-Point Roll Cage Is Recommended.

2. Must Be a Minimum of 1.5” Diameter with at Least .063 Wall Thickness Chrome Molly or Mild Steel Tubing or some type of material of equal strength.

3. NOTE: Roll Bars/Sport Bars in the Bed of the Vehicle Are Not Considered an Acceptable Substitute for a Roll Cage.

4. Doors May Be Trimmed for Roll Cage, But Not Gutted. "Gutted" Refers to Excessive Removal of the Interior Above and Beyond That Which Is Required for the Roll Cage And/Or Other Specific Rules Allow.

5. Doors Must Be Able to Securely Open & Close.

Body and Frame:

1. No Tube Frames. Must be Factory Type Frames. No frames shorter than 109" center of front axle to center of rear axle unless offered from factory and no lengthening. Engine must be lcoated in stock location. Factory Type Fenders on Front & Rear can be made of any material, example, aluminum or fiberglass. Must have Truck appearance. Must have Factory type Cab & operational Doors.

2. You may run with or without hood or tailgate. Hood can be made of any material.

3. No Mixing of Engine and Body Style. Engine Type Must Be Offered By Manufacturer in that Style ½ Ton or Larger Vehicle. (Ex. Ford Engine in Ford Chassis, Chevrolet Engine in Chevrolet Chassis). Must be Full Size Vehicles.

4. All Vehicles May Run ¾ or 1 Ton Running Gear (Drivetrain, Axles, Springs, etc.).

5. All Stock Automotive Glass May Be Removed from Vehicle. Windshield may be replaced with Lexan or Speed Glass. All other Glass, Example, Door Windows, Side Windows or Back Windows may be removed.

6. Drivers Must be Shielded from all Radiators, Oil Coolers & etc.


1. Driver's Seat Must Be Located on the Left Side Similar to Stock lLocation.

2. Anything from Interior may be Removed, such as door panels, window cranks, radios, air duct work, Heater Core or Dash, etc.

3. Firewall Mandatory and Can Be Repositioned with any safe fireproof material, such as heavy gauge aluminum or etc.  

4. Vehicle Is Required to Carry On-Board a Fully Charged, Mounted Fire Extinguisher of A, B, or C Dry Chemical Type, 2.5 Pounds Minimum Capacity in Cab.

5. 4-Point SFI Harness Required for Driver & Passenger.


1. Tow Hooks on Front and Rear are Recommended.

Fuel Tanks/Cells/Pumps:

1. Gas Tank May be Removed and Replaced with a Fuel Cell.

2. All Tanks/Cells Must Have Positive Locking or Screw Caps.

3. Fuel Tanks/Cells Must Be Fully Secured.

4. All Fuel Lines Must Be Isolated from Driver's Compartment.

5. Any Type of Fuel Pump, including Manual, Electric or Belt Driven Allowed.


1. Gasoline or Racing Fuel Only, No Alcohol.

2. No Ether, Nitro, Nitro Methane, Propylene Oxide, Nitrous Oxide, or Nitrous Devices (Nitrous Plates, Nitrous Solenoids, etc.) Allowed.



1. Any OEM Production Type Transmission or Transfer Case Allowed, if Offered by Manufacturer in that Style Vehicle.

2. Aftermarket Shifters Allowed.

3. Any Stall Converters Allowed.

4. Power Glides Allowed in Any Type Vehicle. (Ex. Can run in Ford, Chevrolet or Dodge.)

5. Transbrakes, Electric or Air Transmission Controls Allowed.

6. All Transmissions Must Have a SEMA Approved Shield or Blanket.

Front Suspension:

1. Must be Stock Type Suspension for that Type Vehicle.

2. Front Suspension Swaps Allowed. Ex. Chevy under Ford and Ford under Chevy.

3. All Type Front Suspensions must be stock type components in Stock Location.

4. Upgraded Shocks Allowed on Front, no Coil Over Shocks, Must be in Stock Location.

5. No Shock Towers, Shackle Sliders, Ladder Bars or Housing Floaters Allowed on Front Suspension.

6. Rack & Pinion Steering Allowed.

Rear Suspension

1. Coil Over Shocks are Allowed in Rear, But Must Maintain OEM Type Rear Leaf Spring Suspension in OEM Mounting Location. Leaf Springs must be Connected to the Frame in Shackles/Hangers at Both Ends – Front & Rear.

2. Aftermarket Shackles/Sliders are Allowed

3. Lift Kits are Allowed.

4. All Vehicles May Run ¾ or 1 Ton Running Gear (Drivetrain, Axles, etc.).

5. Can Change / Up-Grade Axles, Rear End Housing, etc.

6. No 4 Link, Z-Link Conversions Allowed.

7. Traction Devices, 5 th Links, Ladder Bars Are Allowed.

8. No Shock Towers Allowed On Rear.


1. All Tires Must Have DOT#. No Cutting or Grooving.


1. Radiator May Be Relocated to the Bed of the Vehicle.

2. Electric Fans and Electric Water Pumps Are Okay.

3. Radiator Must Be Securely Fastened and Shielded from Driver.

4. Must Not Be in the Driver's Compartment.


1. Must Not Be in Driver's Compartment. Must Be Installed with 3/8” Bolts with a Minimum of a ¼” Steel Plate and/or Tube Frame Type Construction. (Bungee Ties or Rubber Straps Are Not Acceptable.)

2. May have Auxiliary Batteries. 

3. On/Off Battery Disconnect Switch Is Required at the Rear on the Passenger Side. The Switch Must Be Located a Minimum of Twelve (12) Inches to a Maximum of Twenty-Four (24) Inches from the Side and a Maximum of Twelve (12) Inches from the Rear.

Engine Specifics:

1. Only One (1) Engine Per Vehicle.

2. Engine Type must be offered by Manufacturer and must be in Stock Location. Engine Plates and Mid Plates Okay.

3. No Mixing of Engine and Body Style. (Ex. Ford in Ford, Chevy in Chevy, Dodge in Dodge, etc.)

4. Factory Firewall Mandatory and Cannot Be Repositioned. Clearance for engines such as big block in Blazer will be Allowed.

5. Maximum CID is 540. Big Block Only.

6. Any Camshaft and Valve Train Allowed.

CRANK: Aftermarket Crankshaft Okay.

PISTONS: Aftermarket Pistons Allowed: Flat, Dish, & Dome Pistons Allowed.

BLOCK: Any Cast Iron Aftermarket Block Allowed. No Aluminum Blocks.

RODS: Aftermarket Rods Okay, Aluminum rods Okay. Aftermarket Rod Bolts Are Allowed.

CHEVROLET HEADS: Any Cast Iron Heads Are Allowed. Aluminum Heads Allowed. No 14 or 18 Degree Heads, No Big Chief or Big Chief Type Heads, No High Port, Spread Port or Hemi Heads Allowed. Example: Allowable Heads: Brodix 2 extra, Dart 360, Dart 320 & Dart Pro 1. or Any Head of This Type. No 18 Degree oval port conventional Heads. Head must be Close to Factory Valve Angle before any angle milling or modification has been applied. Any Modification Allowed.

FORD HEADS: Any Cast Iron Heads are Allowed. Aluminum Heads Allowed. No Big Chief or Big Chief Type Heads Allowed. No High Port Heads Allowed. No Hemi Heads. Exception to the rule, Fords May Run The Revised A-460 Head, such as the EX514 or the Trick Flow Head, But they will be required to weigh 8.2 lbs. per cubic inch. The C-460 Head Will Not be Allowed. . Head must be Close to Factory Valve Angle before any angle milling or modification has been applied. Any Modification Allowed.

ROCKER ARMS: Roller Rocker Arms Okay. Screw-In Studs & Guide Plates Are Allowed.

INTAKE: Any Aftermarket Intake Allowed. No Sheet Metal Intakes, Tunnel Rams or Home made Spacers or Adapters. No High Port Intakes Allowed except on the Ford

EX 514 or Ford Trick Flow Heads, but they will be required to weigh 8.2 pounds per cubic inch.

ALLOWABLE PARTS:  Double Roller Timing Chains, High Velocity Oil Pumps, Racing Oil Pans, and Pick-Up Screens, Up-Graded Fasteners. Oil Coolers Are Allowed.

No Aftermarket On-Board Computer and/or Analysis Equipment Allowed at Any Time.

Carburetor Only:

1. Any Type Carburetors Allowed. No Multi Carburetors.

2. Throttle Pedal Must Be Positive Acting with Return Loop or Arm for Return In Case of Stuck Throttle. Three Return Springs are Mandatory, One (1) on Pedal and Two (2) on Carburetor.

3. No Fuel Injection Allowed.


1. Any Ignition Allowed.

2. No Magnetos Allowed.

3. No Aftermarket Devices such as Ignition Retarders or Advances.


1. Headers Are Allowed. Headers Can Be Run Up or Down.


1. Driveline Brakes Okay.

2. Must Have Brakes on at Least Two (2) Wheels (Ex. Two Front Wheels or Two (2) Back Wheels).

3. Must Be Able to Stop Safely.