From the United Sprint Car Series Web-Site Rules Section: (5/1/04) Wheel Safety Rules Added

ENGINE BLOCK & DISPLACEMENT:
Cast iron engine blocks only (no aluminum) 360 cubic inches plus 1%. Maximum displacement = 363.6 cubic inches.

FUEL INJECTION:
Only single plane 8 port injectors allowed. Maximum 2 3/16 inch (2.187 inch) inside diameter of injector stacks. Larger injectors may be used, if reduced with sleeves or steps for a minimum of 3 inches. No alteration of injector manifold mounting holes will be allowed. No holes may be drilled above the butterflies on injectors. No down nozzles (No fuel injector nozzles mounted in the heads allowed ).

CYLINDER HEADS:
All cylinder heads and valve angles must remain within 1 degree of the original manufacturing (EXAMPLE: Chevy valve angle is 23 degrees) At no time may intake ports exceed 215 cubic centimeters on any USCS-AFR SPEC heads or ASCS SPEC heads. Only two valves and one spark plug per cylinder allowed.

Head Option # 1 - The official SPEC cylinder heads for Chevy powered USCS sprint cars are the Airflow Research 360 SPEC heads ( USCS - AFR 360 SPEC). No altering of the ports of the AFR 360 SPEC heads allowed. Clearance and polishing work in the combustion chamber area is allowed but no work may go beyond the valve seat.

Head Option # 2 - Any 23 degree cylinder heads are allowed with properly installed USCS or ASCS restrictor gaskets. Must hang 0.125 inch into the runner of the head with no alteration of the intake manifold position allowed.

Head Option # 3 - ASCS heads - Brodix part # 27-211, #27223, and #27-222 with ASCS stamp may not be altered in any way. Intake opening no larger than original opening, the only exception being, inlet opening may be ground or polished 3/4 inches or no further into port than the closest edge of the closest letter of the ASCS logo. During this polishing the left side of the letter "A" is sometimes inadvertently brushed with polish wheel. This is permissible as long as letter is still intact. During polishing of inlet port sometimes polish marks may go slightly further than the 3/4 inch. Intake port at no time may exceed 215 cubic centimeters. Intake port polishing on the ASCS heads will be allowed no more than 1 1/2 inches below the bottom of the original seat ring on the back side of the bowl area and no more than 1 inch on the short side. Polishing will be allowed in the combustion chamber area. Polishing will be allowed in exhaust ports as long as the original "ASCS" logo is not affected or port shape is not altered substantially.

PENALTY FOR ALTERING SPEC OF HEADS:
Intentional SPEC head alteration violators will be subject to one year suspension, forfeiture of all points and monies won during that day’s event and a fine of up to $1000.

TITIANIUM ENGINE PARTS:
Additionally: No titanium parts in the engine are allowed except valves and valve spring retainers All oil pans must have inspection plug pans without plug will be subject to pan removal at anytime.

NO COMPUTERS!
No computer operated or controlled parts, such as fuel injections fuel systems, chassis adjusting systems, etc!

TIRES:

Open Tire Rules Apply -  Any Brand of Dirt Racing Tire (i.e. Hoosier – Goodyear – American Racer, etc. etc.)

WHEELS:
Safety Mandate – High Strength Wheels Suggested on Right Side
Foam Mud Plugs Only – NO Metallic or Lexan Type or Style of Mud Plugs