1. Engines must be flathead 12hp and under, must be Factory OEM Block.
2. Flywheels and starter pulleys must be billet steel or aluminum. NO welded on fins. All starter pulleys must have a retainer device to prevent it from coming off the crankshaft.
3. Engines must use OEM stock or OEM replacement piston, must use factory length rod. (Aftermarket billet rods allowed) NO piston pop out allowed. .030 over stock bore max.
4. Stock stroke crank only. STOCK HEAD DIAMETER 1.380 intake and 1.125 exaust aftermarket valves ok.
5. Porting and polishing of block allowed.
6. Must be factory, unmodified cast camshaft. Welded or reground OK. Maximum valve lift is .330
7. No external welding or external modifications allowed to engine block, welding permited in crank case area of block for REPAIR ONLY. All thread through fin area acceptable.
8. Engines to use factory unmodified heads. No recast or billet head, planeing or milling of gasket surface only permitted.
9. Head strap, recommended but, not necessary.
10. Must use factory ignition system (chevy points allowed)
11. Carburetor must be stock, unmodified, must be able to attach factory backing plate for air cleaner. NO velocity stacks allowed. Choke may be removed. (Lakota velocity ring OK)
12. Carbureted engines only. Maximum venturi is 1.00 inch; NO air entering after 1 inch restriction, venturi must be round in shape.
13. All engines must have scatter shield of 1/8 inch steel or 3/16 aluminum, opposite the cam side of the motor, all final drive belts, flywheel and clutch assemblies must be covered 360 degrees with 1/8 inch steel, or 3/16 aluminum and be securely fastened to engine or frame.
14. All exaust must discharge vertically and securely attached no more than 10 degrees straight up allowed.
15. Pumped gas only. NO E85.
16. Tractors must use garden tractor rearends and transmissions, must use factory frames. Maximum wheelbase is 52 inches. Front weights may not be more than 7ft from center if rear axel.
17. All tractors seats must have a minimum of 3 inch back.
18. All tractors must be equipped with deadman throttle.
19. Fenders should extend a minimum of 4 inches the width of the tire.
20. A minimum of 1lb of dry chemical fire extinguisher required.
21. Maximum tire size is 23x10.50x12, cutting and sharpening permitted.
22. ALL DRIVERS ARE REQUIRED TO WEAR A FIRE SUIT.
