Pro Truck Rules

Rocker arms must mount in original position. Chevrolet and Chrysler rocker arm ratio is 1.5 magnum heads us 1.6 and Ford is 1.6. Stamped steel, roller tipped and aluminum roller, rocker arms permitted. No titanium or other lightweight materials permitted. Rocker arms must be stud mounted, 3/8 or 7/16 studs allowed, except for Chrysler, which may be shaft mounted in OEM positions. Stud girdles permitted.

#20 Cylinder Heads

Chevy cylinder heads minimum combustion chamber 53CC (+or -1)

Only General Motors factory produced, production 305 cast iron cylinder heads allowed. Must retain original 2 valves per cylinder. Intake valve maximum is 1.84 inches in diameter and exhaust valve maximum is 1.5-inches in diameter. Stainless steel replacement valves of original length permitted with a maximum stem variance of .018-inch. No interior de burring, polishing or hand blending permitted. Studs may be pinned or screw-in studs with guide plates permitted. Chevrolet head part #12529180 casting, #12558059 (96-99 pick-up truck) are permitted, but #1023906 is NOT acceptable or permitted.

Ford cylinder heads minimum combustion chamber 58CC (+or-1)

Only Ford factory produced 302 cast iron cylinder heads allowed. Must retain original 2 valves per cylinder. Intake valve maximum is 2.02 inches in diameter and exhaust valve maximum is 1.60 -inches in diameter. Stainless steel replacement valves of original length permitted with a maximum stem various of .018 -inch. No interior de burring, polishing or hand blending permitted. Studs may be pinned or screw-in studs with guide plates permitted.

Chrysler cylinder heads minimum combustion chamber 57CC (+or-1)

Only Chrysler factory produced, production 318 cast iron cylinder heads allowed. Must retain original 2 valves per cylinder. Intake valve maximum is 1.84-inches in diameter and exhaust valve maximum is 1.54-inches in diameter. Stainless steel replacement valves of original lengths permitted with a maximum stem variance of .018- inch. No interior de burring, polishing or hand blending permitted. Studs may be pinned or screw-in with guide plates permitted.

#21 Intake Manifold

Only the following intake manifolds permitted with no substitution and must supply a direct vacuum port to hook up vacuum gauge.

* Chevrolet – Elderbrock #7101, #7116 or #2116

* Ford # 7121

* Chrysler #7176 intake may be modified to use with magnum head.

No polishing or porting of intake manifold permitted. No laser treating or micro holes allowed in intake. No drilling or port matching allowed. Plenum may not be altered and no devices are permitted inside runners or plenum to direct flow.

#22 Carburetor

Holley 500 CFM model number 4412 permitted. No polishing, grinding permitted. Choke and choke horn may be removed. Boosters may not be changed. Venturi area must not be altered. Base plate, throttle shaft and butterflies must NOT be altered. Any alteration to pull outside air other than through venture is prohibited. Stock butterflies must be used and cannot be thinned or altered. Idle holes may be drilled in butterflies, screw ends may be cut even with shaft, screw heads must remain unaltered. Throttle linkage must have at least 2 return springs, must supply large direct port for vacuum check on carburetor or intake. Only Holley OEM parts allowed, and must pass official gauge set. May run Willy’s external adjustable metering block but must be approved by tech (if you have questions on part allowed to be used see tech officials before using)

#23 Carburetor Adapter

Only one-piece adapter with a maximum thickness of 1 inch permitted with one (1) gasket per side not to exceed .065 thickness. Plate may be altered on bottom to direct airflow.

#24 Air Intake

An air box is optional. All vehicles participating in a sanctioned race must have a metal air cleaner. Air cleaner must be a minimum of 12 inches in diameter and a maximum of 20 inches in diameter. Air cleaner limited to maximum of 4 inches height. Front of cleaner may be shielded. Anything used to induct air to element is prohibited. Cleaner element may not be altered, sprayed or soaked with chemicals or any foreign substance. Front area of cleaner up to a maximum of one-half of air cleaners diameter and not wider than the height of air cleaner filters can be shielded. Bracket may be attached to firewall to deflect heat but may not be larger than 1-1/2 “ X 1- ½ “ L shaped and must be centered in opening. K & N air cleaners are permitted. Must supply a direct port vacuum on intake or the rear of carburetor for vacuum check. Air box must be made out of sheet metal. No carbon filter or fiberglass. May use Lexan in bottom but must have a metal air cleaner bottom attached to it. All air boxes are subject to approval by tech man. NO PLASTIC CARB HATZ.

#25 Fuel Pumps

Electric fuel pumps prohibited. Only stock mounting mechanical pumps permitted. After market fuel pumps are permitted, but must be of same size and mount in stock location.

#26 Fuel

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