Pro Stock 4WD Truck 4x4
Updated: Jan 18
Unless specifically outlined below in the class specific rules, the Truck General Rules and the overall General rules outlined above apply.
Weights and Wheels
1) Tires must be street legal. No tread alterations of any kind-sharpening, cutting, re- grooving, or tread touch up is not allowed. No larger than 33 x 12.50 x 16 or 305 x 16 only DOT approved with factory stamp. The size must be displayed on the tire.
2) Solid rear suspension allowed.
3) Any rear-end housing size is permitted. Maximum of one-ton front-end housing allowed. No air lockers or electronic locking devices. The width of the housings is to be like the width of the factory housings.
4) Weights/weight bar must not extend forward more than sixty (60) inches from the centerline of front axle
5) Max allowable weight 6200#
1) Engine must be the same make as vehicle. Engine must be in stock location. Rear edge of block to center of axle can be no less than 14”. May only run cast iron blocks with any cast iron heads or aluminum type heads also acceptable are NHRA pro stock legal with wedge shaped combustion chambers, no hemi type chamber (can have spark plug in middle through valve cover), OEM or after market. Any internal engine modification allowed.
2) Any single 4-barrel manifold required naturally aspirated. Sheet metal intake manifolds are allowed.
3) A 1% variance to the engine limit of 500 cubic inches.
4) Maximum engine bore spacing of 4.9 inch.
5) No electronic timing devices.
6) No traction control, no digital boxes.
1) All body components must have factory production OEM frame.
2) Vehicle must retain original wheelbase plus or minus 1⁄2 inch and stock appearance, 133” maximum.
3) Hood scoops optional.
1) Any nonmember or puller that doesn’t conform to rules shall lose 2 inches of
hitch height. Or 200 pounds of weight by their choice.
1) Primary hitch must be secure to vehicle frame in all directions, Hitch stem may be any length, as long as point of hook is not less than 36% of wheel base.
2) Hitch point to rear axles centerline must be a minimum of 36% of wheelbase. This distance cannot change during the pull.
3) Hitch stem angle must not exceed 25 degrees measured on the stem w/angle finder. Main stem must be straight from point of hook to pivot point. (On the same plane).
4) No part of hitch can be attached or come into contact w/ rear axle during pull except the Stem adjuster.
5) Hitch adjuster must not locate more than 6 inches from point of hook.
6) Hitch height cannot exceed 26 inches from point of hook to ground or track.
7) No “L” shaped drawbars.
8) No drawbar angle greater than the angle of the sled chain. Acceptable angle is 0 degree to a maximum of 20 degrees. This will be measured by the angle of a straight edge from the point of hook to the center of the pivot point.
9) All turn buckles that control drawbar height from BELOW the drawbar must be vertical or angle FORWARD from the attachment point on the drawbar to axle housing. Attachment point on axle cannot be above centerline of axle housing.
10) All turn buckles that control drawbar height from ABOVE the drawbar must be vertical or angle BACKWARD from attachment point on drawbar to frame.
11) Maximum hitch height shall be 26 inches. This maximum cannot change during pull.
12) Drawbar to be made of steel, minimum of two (2) square inches’ total material at any point. This will include the area of the pin with pin removes. Pins will be minimum of 7/8-inch diameter. Drawbar must be equipped with steel hitching device constructed of not more than 1 1⁄2 inch square nor less 1-inch square (1 1/8-inch round stock) with an oblong shaped hole of 3 3⁄4 inch long by 3 inch wide.
13) No cam type rear ends. All rear ends must be welded or bolted by a minimum of 3 bolts per side solid with a minimum of 3 5/8 grade 5 bolts per side to the frame.
1) Aftermarket transmission and transfer case allowed.
Fuel & Water
1) Alcohol fuels and propylene oxide are not allowed.