Pro Stock Class Rules

Pro Stock Rules

This class is open to youngsters age 12 - 19. Pro Stock will be open for drivers up to age 21 that have had 3 years prior memberships and/or pulling experience. This class is a high budget class for experienced pullers. With open RPM tractors on the loose there is never a dull moment! Tractors range from 65 to 90 horsepower.
    1.  Class open to 1100 lb and 1200 lb hooks at Thundering Valley and at the fairs.

    2.  All tractors must use lawn mower type motor.  45.6 cubic inch V-twin maximum, 50.5 cubic inch Single cylinder maximum.

    3.  Unlimited rpm limit.

    4.  Relocation of components allowed.

    5.  Modifying of body panels allowed.

    6.  Bar lug and V-tread Pro pulling tires allowed.  Bar lug tires may be cut.

    7.  7 foot limit from center of rear axle to furthest point front including any weights.

    8.  All tractors must have wheelie bars.

    9.  All tractors must have adjustable hitch with no less than 1 1/2 inch hole for hook.

    10.  All tractors must have rear mounted tether kill switch that shuts off the ignition and electric fuel pump.

    11.  Flywheel must be covered 360 degrees.

    12. If you are running a stock flywheel for make and model of the tractor, you cannot run over 4000 rpm's.

    13.  Over 4000 rpms, shroud must be built according to Safety rules, under 4000 rpms stock shroud allowed.

    14.  All belts must be covered.

    15.  All tractors must have hood.

    16.  All tractors must have rear fenders.

    17.  No turbos.

    18.  All tractors must use stock rear end.

    19. Pro stock shielding rule is listed under the safety rules.

    20. Maximum carburetor ventri size 1.2 inch for single barrel carb, 22 mm for two barrel carb.  Ventri must be round in shape.  Choke plates may be removed.  Single cylinder motors can use up to 53 mm carb. 

    21. V-Twin motors must use stock heads.  Single cylinders may use billet head. 

    22. An exception can be made for entrance into this class if the driver has had prior pulling experience and there is unanimous approval  from all of the Tech and Safety Crew members.

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