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:

1. 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)
2. IMCA mods with flat tappet must be a minimum 2200 lbs. after the heat or feature race.
3. 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. .


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USRA Modified Rules