- Modified minis are limited to a maximum of 575 cu. In. of naturally aspirated engine or 380 cu. In. of 6-71 supercharged small block w/10% overdrive.
- Naturally Aspirated engines less than 512 cubic inches are allowed to weigh 2,000lbs.
- Naturally Aspirated engines over 512 cubic inches and supercharged engines are allowed to weigh 1,950lbs.
- All engines are limited to (2) valves per cylinder.
- Engines are limited to (1) spark plug per cylinder
- Modified Minis must meet general tractor shielding and safety criteria.
- All drive train, excluding additional manual transmission, must be enclosed in 5/16″ minimum steel or 3/8″ inch aluminum, round, inside diameter not to exceed 2 inches more that the outside diameter of the largest universal joint, fastened every 6 inches or closer, with 3/8″-inch or larger bolts, Grade #5, or butt and seam welded, and securely mounted to vehicle’s frame. Applies to all vehicles with exposed driveshaft. No more than ¼ -inch of end of driveline shall be visible with driveline shielding in place.
- Note: If U-joints are used in any drive shaft application, the shielding must be 5/16-inch steel or 3/8-inch aluminum with 1/8-inch steel insert in aluminum. The insert must be a minimum of 6 inches wide.
- All Modified and Modified Mini mounts, two rear engine mounts, and a support saddle for rear of transmission, with 1/2 –inch maximum clearance; OR
- Two front engine mounts, support saddle at rear of engine, with ½ inch clearance, and a mount at rear of transmission.
- Note: This is to prevent engine or transmission from dropping if breakage occurs.
- No portion of the tractor shall exceed 8 feet forward of the center of the rear wheel.
- Tread width (foot print) not to exceed 6 feet in width.
- Drawbar height to be 13″
- Drawbar length to be no shorter than 6″.
- Drawbar and hitching device to be one-piece construction, with a minimum of 1 inch solid steel material.
- No hollow tubing is permitted.
- Front part of drawbar is to have a minimum of ½-inch cross sectional thickness to remain on the front side of hole where drilled.
- Minimum ½ -inch pin.
- Drawbar height adjuster or hold up/down device to be no more than 5 inches from hook point. There must be a minimum of ½ inch metal remaining where hole is drilled. Hose clamps may not be used for any drawbar related devices.
- The drawbar receiver or the material where the front of the drawbar is attached must have a minimum of 1/4 –inch thick metal on each side of the horizontal pin drawbar.
Point of hook
- The point of hook is to have a minimum of a 2-inch round hole, maximum of 2-1/4 inch hole.
- The thickness of material around the hole must be a minimum ¾-inch thick.
- Point of hook to be no more than 3/4-inch cross sectional thickness.
- Maximum tire size is 18.4 x 16.1 with a maximum of 143-inch circumference when mounted on an 18 inch wide rim and inflated to 10 psi. The ground patch is not to exceed 19 inches on original tread.
- No tire repairs (boots, section repair, vulcanized spots, etc.;) will be allowed.
- Skid plate must be of the two types listed below:
- Skid plate mounted to center of axle must be a minimum of 10 inches wide with rolled edges both front and rear. Plate must be a minimum of 4 inches in length. Plate must be centered and securely mounted to front axle and/or frame.
- Skid plate mounted inline with each frame rail (on both sides) equal in strength to frame rail material.
- Skid plate surface to be minimum of 2 inches wide and 10 inches long with a minimum 2 inch curve when measured from the front most part of rolled edge.
- Note: Both types must be able to support the weight of the front end when checked with a jack. Maximum ground clearance not to exceed 2 inches with front tires in normal operating position.
All general rules apply (where applicable).