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Southern Mod 4's Rules


Quick Find: 

Chassis     Body     Bumpers     Safety 
Suspension     Engine     Drive Train     Tires     Weight 

Questions concerning this class call:       Jr. Delaney (940) 882 - 5226


These rules are written in hopes of creating interest in an economical 4-cylinder racing that travel to several area tracks and race two to four times each month on both asphalt and dirt.

The rules are open enough that several older cars in the area can qualify and be competitive.   They are written with economy in mind, but are open enough so that work, ingenuity, and driving ability can make any car competitive.

There are several factors incorporated into these rules to hold cost to a minimum and equalize the field for all competitors, some of these are:

  1. Engine displacement limits
  2. Manifold vacuum
  3. Tire restrictions

The class will draw for starting spots in the heats. The line for main will be how you finished in the heat race with the winner in each heat race starting from the back. We will provide the racetrack with heat line ups and main event line up. The class will have its own tech man.



1    Any floor pan, OEM frame, or fabricated tube chassis allowed.      
      Minimum wheelbase is 90”.

2   The rear of the engine must be at least 64” from center of the rear end housing.



3   Any OEM body or sheet metal body (Flat sided late model or modified type) will be                  allowed. Body must be neat in appearance and painted.

4   Each car must display at least 12” high numbers on each side of the car, and a 6” number       visible from the front and rear of the car.    
     All numbers must be in contrasting colors and
 easily readable.



 5   Must run front and rear bumpers.
      The bumpers must be sagely constructed of 2” maximum
 tubing, with no protruding ends       and not extend beyond outside of the wheels.

 6   Nerf bars must be mounted flush with the body, no sharp edges and constructed of no             more than 1 ½” tubing.



 7   Must have a minimum of a 6-point roll cage with at least three door bars on the driver’s           side.
      All cars must be safely constructed and inspected and deemed safe before allowing it                 to compete.

 8   Must wear an approved fire retardant fire suit and a minimum of Snell 2000 or                         approved helmet.

 9   Must be equipped with 3” seat belt and shoulder harness, safely attached to the frame or          roll cage.

 10  Must be equipped with an approved fuel cell that is safely installed in the car.
       Each car must 
have one 12 volt battery securely attached to the frame or roll cage.

 11  Each car must have at least three wheel working brakes.


12  One shock and spring allowed per wheel.   
      Weight jacks, leaf spring adjusters, and coil overs
 are allowed.


13   Any inline 4cyl single cam engine that does not exceed 2400cc will be allowed.

 14   Allowed to have no more than a single 500cfm, 2-barrel carb. with no more than 2”                   spacer.


16   Head must be stock, factory produced OEM type head that bolts to the block with                    no modification.  
       Absolutely no porting, polishing, or port matching of any kind will be 

 17   Any type of cam, lifters, or followers will be allowed, but engine must pull a minimum of           12” vacuum at 1200 RPM, measured at a vacuum port on the intake.

 18   Absolutely no stroker motors.    
        All engines must run factory stock crankshaft and rods.
        No aftermarket or lightweight engine parts will be allowed.

 19   A 1” minimum inspection hole should be installed in the oil pan, or competitor may                     be asked to remove oil pan at the track.

 20  May run any distributor driven ignition sty.   
        No magnetos or crank trigger ignitions.



20   Must run OEM stock clutch and pressure plate on stock OEM steel flywheel.

21   No mini clutches, ram couplers, buttons, or any other aftermarket clutches.   
        A minimum of
 a 1” hole is required in bell housing for inspection of clutch assembly.

22   Transmission must have operable forward and reverse gears.    
        Automatics must have an 
OEM Functioning torque converter.

23   Any OEM rear end may be used and may be locked.   
       No quick changes or tru trak allowed.
       No locker type differential.


24   Tires must be DOT street tires with a minimum tread wear of no less than 360, or                     Legends Tires and have a maximum width of 9 ½ “ measured with a NO GO gauge.


25   Must weigh no less than 2000 lbs., including driver.    
        Each car can be weighed as it comes 
off the track at the end of each race.

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