2015 IMCA Northern Sport Mod/Rat Mod Rules

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 IMCA Northern Sport Mod will use IMCA Rules from IMCA website. All other Rat Mods will use these grandfathered rules for






This is a low cost open wheel class that uses readily available production components in construction.  This class is designed to be a crowd pleaser and provide the drivers with competitive door to door racing. Allow Lovelock Sports Mods to race in this class.



1.      Engine maximum displacement is 323 cubic inches.


2.      Flat top pistons only.


3.      Single flat tappet cam only.  No roller drive train.


4.      Roller tipped rocker arms allowed.


5.      Must be naturally aspirated.  One (1) two barrel carburetor. 4412/500 cfm, one (1) spacer/adapter of one (1) inch maximum is allowed.


6.      Single/dual plane manifolds OK.


7.      No purpose built race engines.


8.      No mid/rear engine vehicles.


9.      No front/all wheel drives vehicles.


10.  No electronic traction control devices allowed.


11.  Engine heads and block shall be cast iron with OEM casting numbers.  V-6 motors can run aluminum OEM heads. V-6 blocks must be cast iron or World Product casting # head.


12.  Heads will be as delivered from factory with no modifications.  No porting, profiling or polishing.


13.  Number one (1) spark plug shall be no more that sixteen (16) inched behind spindle centerline.  (V-8 and inline 6 engines) V-6 engines will be measured from the rear of block to spindle centerline a total of 34 inches.


14.  Engine offset must be kept within two (2) inches of original frame’s center.


15.  Cooling system may be modified.  Any overflow tubes must be directed to the ground, between frame rails.  Radiators will be mounted in front of engine.


16.  Transmission must have one forward gear, a reverse gear, and a neutral position.  Only OEM production transmissions will be allowed.  Manual transmissions must have a working single disc-type clutch with an all steel flywheel.  Automatic transmissions must remain in OEM stock automatic case with a functional torque converter.  Original bell housing must remain.


17.  Manual transmission: Aluminum flywheel and 7.5” clutch allowed with after market SFI safety bell housing only.  Car must have operation clutch pedal in cockpit.  Car must be able to start in neutral and shift into gear to drive off. 


18.  Automatic transmission must have working torque converter.


19.  No “in and out” boxes or quick change devices allowed.


20.  Must have an approved scatter shield or blanket.  Scatter shield shall be constructed of not less than inch by three (3) inch steel, 270 degrees around flex plate/flywheel.  Steel bell housing is allowed.


21.  No purpose built racing rear axle allowed.  Must be semi-floating.  Lockers are allowed.


22.  Drive shaft must be solid, one piece, and painted white.  A 360 degree drive shaft hoop required.  If sitting over drive shaft there must be a complete hoop.


1.      All 318/Rat Mods bodies must look like IMCA modified or a real production car or pickup.  Bodies may be steel, aluminum or fiberglass. No vans or sedan delivery bodies.


2.      Body must retain from body donor, the base of windshield pillar to window post and entire rear quarter panel with roof.  Doors can be made is sheet metal.  Doors must conform to rear quarter panel.


3.      Any full frame vehicle can be used.


4.      Entire body must be inside of all four wheels.


5.      Body shall be enclosed at the rear and resemble production vehicle.  Plastic tail light lens and trim are allowed.  Plastic vehicle names or manufactures are allowed on rear only.


6.      Center or left hand drive allowed.  Driver must sit in front of u-joint and must have a protective plate around u-joint.


7.      Engine hood cover required.  Engine compartment will remain open, no side panels.  Hood sides may have a maximum of two (2) inch drop and hood shall not extend above mounting point.  Hood must extend minimum two (2) inches past radiator.  Front grill or nose piece is optional.


8.      Maximum hood scoop height is six (6) inches.


9.      Minimum 18 gauge steel firewall and steel floor.  One eighth (1/8) steel cover, to include sides, over driveline, on center drive cars.


10.  The body may be channeled over the frame.


11.  Minimum of ninety-six (96) inch wheel base right and left side wheel base shall be within one (1) inch of each other.


12.  Removal of frame behind rear most suspension mounted is allowed.


13.  NO part of racecar can be lower than four (4) inches measured from the ground up.


14.  Banana wing is optional.  Wing will be four (4) feet by four (4) feet with no side boards over one (1) inch extending top or bottom.  Or one spoiler the width of the body and no higher than eight (8) inches at any point. No wikerbills. No other aerodynamic devices allowed. No adjustments from the cockpit of the car allowed.


15.  Maximum spoiler height is six (6) inches measured from deck up.


16.  Center of bumper, front and rear, must be 18 inches, plus or minus two (2) inches, from the ground up.


17.  Steel bumper must be used both front and rear and securely mounted with minimum 3/8 inch bolts or welded to the frame.


18.  Bumpers must be made of minimum 1.25 inch OD tubing, .065 wall on front and .095 wall on rear and able to support car when lifted by wrecker.


19.  Two bar from bumpers must be mounted to the frame end-to-frame end, no wider that the width of the frame horns, with the bottom loop parallel to the ground and no more than eight (8) inches or less than six (6) inches center to center from top loop.


20.  Stock OEM front cross member with independent suspension.  Lower control arms OEM with chassis mounting location not moveable.  Some modification allowed for springs, shocks mounting etc.


21.  Tubing frame rails behind cross member allowed.


22.  Top loop must be directly above bottom loop.


23.  Two-bar rear bumper shall be no wider than the outside of the rear tires and no narrower than the inside of the rear tires with the bottom loop parallel to the ground and no more than eight (8) inches or less than six (6) inches center to center from top loop.  Bumper must extend out from frame a minimum of ten (10) inches.


24.  Steel nerf bars are REQUIRED and must not extend beyond the width of rear tires.


25.  IMCA chassis are allowed, but must correspond with suspension, steering and brake sections of these rules. Engine rule also.


1.      Front suspension type must be OEM as delivered with frame and must replace with stock parts.  Non-adjustable tubular upper control is OK.  Lower control arms must be OEM. Top mounting points may be removed.


2.      Shock mounts location is open.


3.      Any typed of front springs allowed.  Mounting locations open.  One springing device and one shock per wheel.


4.      Any type of rear spring allowed.  Mounting location open.  One spring and one shock per wheel.


5.      Three-link rear allowed two trailing arms and one pull bar, or two trailing arms and one torque arm, or leaf spring locate axle. No four-link allowed. 


6.      No fabricated spindles.


7.      Spindles can be ground for brake caliper clearance only.


8.      If used, front sway bar must on OEM approved.


9.      Suspension, steering and rear end parts must be steel.


10.  Any make production rack and pinion allowed.


11.  Steel steering shafts and knuckles only.


12.  Steering may be modified to suit driver’s taste.  Must be kept between frame rails.


13.  Steering quickeners are allowed.


14.  No device allowed that would enable driver adjustment to alter wheelbase or for weight jacking while car is in competition.


15.  OEM auto or truck leaf springs must be used in rear suspension as intended by frame manufacture.  Mounting points may be changed.  Single or multi leafs OK.  Leaf springs must support race car.  Spring sliders OK.


16.  One shock per wheel only. No remote adjustable shocks.  No air shocks/bags allowed.


17.  Four (4) coil over per car, one (1) per wheel allowed.  Coil over eliminators are allowed.  Maximum of five (5) shocks.


18.  Brakes are open as long as spindles are OEM.  Brakes are required on at least three (3) wheels and may be converted to disc.  Driver brake bias control is allowed.


19.  Heim joints allowed only is steering shaft supports and shocks, torque arm, and pan hard bar.


20.  Weight jacks OK.


1.      Wheels must be steel and no more than ten (10) inches wide.  Right rear wheel only, is allowed a bead lock.  Wheel spacers shall not exceed one (1) inch thick.


2.      DOT tires, track tires, Eagles or Hoosiers allowed. No Dirt Bosses allowed.


3.      Mandatory one (1) inch lug nuts.


1.      Roll cage shall be constructed using 1.5 inch OD steel tubing or greater with a minimum wall thickness of .095 inches.  No tubing on the car can be any greater that two (2) inches in diameter.  Six (6) point cage consisting of a four-point center section, and “kicker bars”.  Center section of cage must consist of main hoop with “X” bracing and halo that clears the drivers head when strapped in with helmet on. The four points of the cage center section must be securely welded to the car’s frame rails.


2.      Rear kicker’s bars are required to have cross bracing or any type of reinforcement.


3.      Front cage hoop permitted.

4.      Bar across back of engine is required.


5.      No brace bars forward of cage may be higher than hood height.


6.      A minimum of three (3) sides door bars, at least 1.5 inch OD is required on each side of car if center drive.  Left side drive requires at least two (2) vertical bars on right side.  They must be as parallel with the frame as possible and located perpendicular to the driver so as to provide maximum protection for the driver.  Bars should not cause difficulty in getting into or out of vehicle.


7.      Sidebars must be welded to the front and rear of the roll cage members.


8.      Full size window nets are required on driver’s side or both sides if driver sits in center.


9.      Window nets to be mounted so latch is at top front or window.


10.  Roll cage padding will be mounted to all areas of roll cage when the drivers’ body may come in contact with the cage or any other part of the interior.


11.  Each race team must have a fire extinguisher in or on the trailer or rear of the tow vehicle. Must have car # painted on it and accompany driver to pre tech.


1.      Pump gas or race fuel allowed.


2.      No alcohol or nitrous oxide allowed.


3.      Electric fuel pumps allowed with functional inertia switch in drivers reach. 


4.      Car must weigh 2400 lbs wet with driver at the end of the race.


5.      Loose object and/or weights no to be used outside of the body or hood area.


6.      Ballast must be secured by two half-inch bolts or equivalent structural engineering.  Ballast must be painted white and have the car number on it.


7.      No more than three (3) foot of rubber hose on fuel system may be hooked to stock fuel line. Must have ground strap.