download or printing - Modified Rules
USRA Modified Rules -
Modified rules will be set as USRA RHS modified rules with an 8000 rpm or less chip required.
IMCA modifieds may run with the following provisions:
- IMCA mods with flat tappet cams and cast iron cylinder heads are not required to run a rev chip. If no chip is used be prepared to show proof of flat tappet. (valve cover or distributor removal)
- IMCA mods with flat tappet must be a minimum 2200 lbs. after the heat or feature race.
- IMCA mods may run a 7” spoiler.
American Racer or Hoosier G60 and KK704 tires will be permitted at Southern Oklahoma Speedway. Please check USRA rules for tire requirements.
Mufflers are required. Cone, 3-ring, or perforated inserts or IMCA609 mufflers are allowed.