TIRES: Maximum 18.4-38
CYLINDER BLOCK OR CRANKCASE: Naturally aspirated engines only. Small blocks must have been originally manufactured with less than 370 CID and may not exceed 460 CID. Big Blocks may not exceed 810 CID.
Approved chassis and small block engine combinations:
AC 190 with 301, Cockshutt 570 with 339, Ford 6000 with 300, International 460/560 with 301, 310, or 360, MF 1100 with 354, MH 203 with 330, Oliver 77/88 with 310 or 320.
Approved chassis and big block engine combinations:
AC 190 with 426, Case 900/930 with 504, Cockshutt 570 with 478, Ford 6000 with 401, International 460/560 with 466 or RD501, John Deere 4010 with 466, MF 95/97 with 800, MM GVI/GVD with 800, Oliver 77/88 with 478.
Approved sheet metal upgrades for small and big block chassis/engine combinations as follows: AC D-21, Case 1070, Cockshutt 1800, 2050, Ford 8000, IH 656, 706, 756, JD 4020, MM G1000, Oliver 1600, 1800, 2050
(Combinations not listed above subject to approval.)
HEADS: Cast iron heads only and must be from same engine manufacturer. No over head cams allowed.
FUEL SYSTEM: Gasoline, Ethanol, Methanol or Diesel. Non-nitromethane and non-polypropylene oxide based oxygen additives are acceptable. Fuel will be tested following these specs: 755 s.g. @ 60F for gasoline, ‹0.800 s.g. @ 68F for methanol and ‹0.820 s.g. @ 68F for ethanol. Small blocks may use: 1) one single bbl updraft carburetor with an original manufactured throttle bore not more than 3.1875″ and modified bore of not more than 3.3125″ 2) a single non-predator style down draft 4 bbl carburetor; 3) up to three 500 cfm down draft 2 bbl carburetors; or 4) fuel injection through a throttle body air valve not more than 4.00″ in diameter. Big Blocks may use one single bbl updraft carburetor with an original manufactured throttle bore not more than 3.1875″ and modified bore of not more than 3.3125″. All must use intake manifold with common plenum.
HITCH: Hitch must not exceed 20″ in height or be less than 18″ from center of axle to hooking point. No part of draw bar may extend rearward beyond point of hook. Hitch must be stationary in all directions. No clevis. Hitch must have opening 3″ wide by 3.75″ inches long and must be at least 1″ thick.
HOOD, GRILL, FRAME, TRANSMISSION, REAR END, AXLE: Must be for that make and must maintain stock appearance. Front ends may be homemade with a maximum center of front axle not to exceed 12″ in front of grill. Frames may be tubular but must be covered with sheet metal or aluminum.
TOTAL LENGTH OF TRACTOR: Maximum length 12′ from center of rear axle to the furthest point forward, including weights.
SAFETY EQUIPMENT: Helmet, Fire Suit, Wheelie bars, Roll cages, front skid plates, kill switches, fire extinguishers, fenders, side shields, SFI flywheels and pressure plates – no cast iron, scatter blanket or steel shields, no steel fans, all electric fuel pumps must be wired to the kill switch. Wide front axles only.