Hilliard Winter Championship

Pro Stock   13 " hitch - 1050#​

1. Single cylinder Pro Stock is defined as any tractor having a one cylinder

    air cooled four cycled flathead, commercially produced block engine. 

    Sleeves and welding are permitted. Commercially produced blocks means:

    Kohler, Wisconsin, Briggs, Tecumseh. Any other than these, then, the

    Hilliard Tractor Club, Inc. must approve. If a copy is being made, engine

     must meet manufacturer’s spec’s for engine being copied for: crank and cam

     location, deck height, two valves same side, valve angle (max valve single is

     6 degrees) and factory Kohler head bolt pattern of  other than stock.

2. Original carburetor may be used. Stand off pipe or ram tubes are permitted. 

     Choke may be removed, single carburetor only. Air restricting venturi must

     be in the middle third of carburetor and must be round and not larger

     than 1.200 restriction. Must be a Kohler type carburetor if other stock for that

     engine model being used. Recast carburetors may be used but must be

     patterned after Kohler or Carter Model N Carburetor and meet these spec’s.  

     Maximum round throttle area outside diameter 1.675. Maximum round choke

     plate area outside diameter 1.900. Maximum outside diameter of fuel bowl

     2.350 (stock Kohler bowl). Maximum length of main carburetor body 3.500.
3. All tractors must have a grill and hood.
4. Tractors must run on alcohol with NO ADDITIVES (CLEAR).
         Bring your own alcohol. Subject to fuel check.
​         See general rules for penalty if caught with illegal fuel.
         Fuel will be checked and carburetor venturi will be measured.​
5. No pressurized fuel tanks. No nitrous oxide. (Naturally aspirated only).
6. 50.5 cubic inch limit. 
7. Wheel base 56 inches.

8. No pressurized oil systems.
*All Hilliard general and safety rules will be strictly enforced.*