2021 MINI STOCK RULES
May 8th Exhibition
COMPETING MODELS AND BODIES – Any 1970 or newer American or Foreign 2 or 4 door hardtop car produced with a min. 90″ wheelbase. No Jeeps or high-performance models. Any 2-wheel drive, 3 or 4 cylinder or 2 rotor engines. Front or rear wheel drive. No rear or mid-engine model cars. All cars must maintain stock OEM body for year, make and model. Fiberglass, steel or aluminum complete stock appearing bodies are approved. No Carbon fiber, Kevlar or titanium parts. Roof must remain stock and out of stock material. Hood and deck lid pins required. Full stock steel floorboards and firewalls required in stock location. Rear trunk area may remain open. 4″ x 50″ rear spoiler top 2″ clear lexan.
BUMPERS – Stock or fabricated bumpers are required. Front and rear bumper must be fastened to the fender and or quarter panel.
WINDOWS – A windshield made of Lexan may be used. Minimum thickness is 1/8 inch. Windshields must be supported between the dash bar and the roof halo bar with a minimum of two (2) evenly placed metal straps 1/8 inch by 1 inch or a single 1.5 inch bar in the center of the windshield welded to the dash bar and the roof halo bar. Wire mesh minimum .5” allowed. No back window allowed, rear side Lexan windows permitted. Driver side window net is required on all cars. Net material must be minimum 1 inch wide and have openings of at least one (1) inch. Net must be equipped with a quickrelease device on the top left corner. Mirrors ok.
FRAMES – Full NASCAR type roll cages mandatory. Bars must be a min. of 1 1/2” O.D. X .090” wall thickness, gusset as necessary for strength. Minimum of three (3) door bars required on both sides. Right side can be straight. Engine must remain in the stock location. Fuel cell protector required, no more than the width of the frame rails. Main roll cage uprights must be fastened to floor of uni-body cars with a minimum 3/16” thick plate, top and bottom, at all four corners. Plate must be a minimum of 4” square, with (4); 3/8” grade 8 bolts at each location. Roll bar padding must be used at any point where driver may make contact. Door bars must be covered with a 1/16” thick steel metal plate, top to bottom, from front and rear uprights, welded to outside of bars. Stock frames only for year make and model. No modifications allowed. Trucks may notch the rear frame section to clear the rear end housing in order to lower the truck. Trucks may also move the rear shocks to lower the truck.
WEIGHT, WIDTH AND WHEELBASE – Min. weight 2200lbs and max. 57% left side weight at anytime. Trucks min weight 2265 and 57% max left side weight at anytime. Min. wheelbase 90″ must remain as factory produced. Maximum overall width (front or rear) shall not exceed 64” from inside wheel to outside of wheel. Front tire width will be measured at spindle height. All lead must be securely fastened to frame using (2)-1/2” bolts or enclosed in a rail with ends secured to prevent loss or movement of weight. All lead must be painted white and have car number printed on it. No lead is not to be mounted behind or on to the rear end housing, as well as, no further forward than the motor. Any lost lead will be subject to fine of a minimum $10 per lb lost.
ENGINE – The engine must be stock for year make and model. No truck engines or parts in cars. No turbo or supercharger. No titanium parts. Steel rods only. Stock length rods ok. Only 5.7 aftermarket rods produced by Manley or Esslinger allowed. Stock fuel injection add 50 lbs. 10.0 to 1 max compression ratio. Engine oil coolers allowed. No dry sump oiling. Oil pan must have a minimum 1” inspection plug inline with #2 rod. Aftermarket oil pans, valve covers, water pump, fan pullies are allowed. No “stroker” or lightweight cranks allowed, factory OEM unmodified cranks only. Heads: Stock heads only. A stock head will be characterized as a cylinder head which was offered as standard equipment with no performance advantage. Stock for year, make and model 2 plug head add 50 lbs. No special performance options will be allowed, including but not limited to, oversize valves, special cut valves, relocated intake or exhaust bowls or ports. Stainless steel valves approved. No porting or polishing will be allowed. No roller rockers on the valve. side or cam side permitted. Max. cam lift is .480” measured at the valve. No billet camshafts. Cast iron camshafts only. 2302 cc max. plus max. overbore .060” Trucks 2366 cc max plus max overbore .060” Engine Blocks: Stock blocks only. No modifications allowed. Stock stroke for engine being used. No Teflon coated parts. Stock lifters only. Solid lifters permitted. Stock type timing chain or belt only. No gear drives allowed. No crank lightening or grinding allowed. No after market lightweight cranks allowed. No titanium parts allowed. Trucks may use approved aftermarket connecting rod. (call for approval)
CARBURETOR – Stock Holley list 7448, 350 cfm carb only. Must remove choke butterfly plate, shaft and linkage. No other modifications allowed. No VDL, CARB shop or any other aftermarket re-worked carbs allowed. 2 carburetor return springs required must be mounted to engine block. Any unmodified OEM intake manifold, no turbo intakes, and max 1” thick carb spacer or adapter. No vacuum leaks AIR
CLEANERS AND FILTERS – No cold air induction allowed, K&N air filters are allowed. No air deflector allowed on front. Air filters only. Top and bottom of air cleaner must be solid and same diameter. Tubes, funnels, or any device which may control the flow of air, will not be permitted inside the air cleaner or between filter housing and carburetor.
ENGINE MOUNTS – All mounts must be securely bolted and adjustable mounts are not permitted.
ELECTRICAL SYSTEM – Stock ignition only. No performance after market distributors, components, or magnetos allowed. No msd, or dui components allowed. No traction control. All cars must be equipped with a master electrical switch located in the cockpit of the car. The switch must be within reach of the driver and safety crew from the left side of the car, switch must shut off car. Batteries must be securely mounted within the confines of the body and behind the driver, in front of the rear axle and contained in electrically insulated container. No marine or plastic type boxes allowed.
ENGINE COOLING SYSTEM – Stock or electric fans are permitted must have shroud. Water overflow catch can unit required. One (1) quart minimum, vented out to windshield, metal or plastic, mounted in engine compartment. No anti-freeze or similar products. This is a finable offense. Water Wetter ok. Any radiator in the stock location.
ENGINE EXHAUST SYSTEMS – Any Stock OEM cast exhaust manifold, steel or stainless steel headers are approved. No aluminum or coated headers. An approved muffler is mandatory, must not exceed 95 db @100 feet. Exhaust must extend past driver’s compartment and remain under car. Exhaust may exit on passenger side of race car in front of right rear tire. 3″ max exhaust pipe.
DRIVE TRAIN – Stock type clutch and flywheel for model being used only. No lightweight cheater parts. Clutch disc must contain all magnetic steel parts. Stock steel OEM or after-market steel billet flywheel. Aluminum flywheels are not allowed. Min. weight of the flywheel is 16 pounds. Steel scatter shield mandatory. Track scales will be official. Stock type transmission only. No modifications. All gears must be operable including reverse. Steel locked, limited slip, or positive-traction differentials are permitted. Rear end must be centered in car. Steel Floater type rear ends are permitted. No hollow axles. No Quick change rear ends. Any OEM steel rear end allowed. Must be mounted exactly as old rear end that was removed, may be used in any MFR line. 2 driveline straps, 1” x 1/8” required, mounting to be within 6” of the U-Joints are required on rear drive vehicles. Steel Drive shaft must be painted white and have car number for on track visibility in the event it should become separated from the car. No cambered or toe in rear ends. Cars with independent rear suspension call for approved modifications. No 9” rear ends.
SUSPENSION AND BRAKES – Stock OEM lower control arms for make and model, no modifications allowed. Stock OEM upper control arm for make and model, no modifications allowed. Any OEM factory production type of balljoint may be used. No “Mono Ball” ball joints. Upper ball joints may be moved to adjust camber and eliminate binds. Stock steel unmodified OEM spindles for make and model. Trucks call for approved aftermarket stock replacement drop spindles. No heim joints. Stock type bushings. Stock OEM for make and model steering components. Stock or stock type replacement steering rack permitted. Racing springs ok. Lowering blocks allowed. Sliders blocks approved. No coilovers unless stock production for your year make and model. All other suspension components must be of original design and origin for the chassis used. No after market look alike parts to widen suspension. Any steel nonadjustable, non-rebuildable, factory sealed (welded) shock that fits the stock mounts may be used. 50/50 valving only. Shock ends must be the same as OEM shocks. No heim joint or tie rod ends. No remote shocks. No spacing shocks up or down. Stock mount only. One threaded weight jack bolt may be used for each spring aligned with the coil. After market pedal and master cylinder assemblies allowed. Rear disc brakes allowed. Stock steel calipers. All components must be steel. No light weight parts. Stock make and model brakes. 4-wheel hydraulic brakes required, and all must be in good working order. One adjustable brake bias valve allowed. Any steel 1 piece sway bar mounted in the stock position. Mounted with rubber or urethane bushings. Outer may be adjustable. No moving of suspension mounting points front or rear. If car has crash damage and has been repaired the mounting points must be to the stock specifications. Rear upper shock location may be moved to accommodate the lowering of the car or truck. No travel limiters of any kind.
STEERING COMPONENTS – Stock steel OEM for make and model steering components only. Quick release steering wheels are required. Steering column must be collapsible. U joints are acceptable.
FUEL SYSTEM – Pump fuel only or track race fuel only. No additives, octane boost, or methanol. No cheater fuel of any kind. All cars must be equipped with an approved fuel cell, securely mounted in the trunk area as far forward as possible. Minimum 8” ground clearance. Fuel cell must be mounted with steel framework (1 inch x 1 inch, .065 inch minimum) and must have a vent hose and the hose must have a check valve in the end. Fuel cell must be totally enclosed in an 18 gauge steel box with a ½ inch drain hole in the lower right rear corner. Ground strap required from fill neck to frame. Tethered cap. Maximum fuel capacity 22 gallons. No electric fuel pumps permitted. If the fuel line runs through the drivers compartment it must pass through a metal tube sealed at both ends and brightly marked “do not cut fuel line”. Must have fuel cell protection bar.
TIRES AND WHEELS – Steel wheels are mandatory, max 8” width x 13” any offset. Tire and wheel must stay inside of fender and quarter panel. Stock type after-market long wheel studs allowed and recommended. All studs must have threads showing through the lug nut. No Bleeders. Wheel spacers and wheel adapters allowed. American Racer – OSS Approved tire only.
Seats and Safety Equipment – For all safety equipment. It will be the sole responsibility of the driver, not the track, their agents/officials or corporate officers to ensure that his/her safety equipment is correctly installed, maintained, and properly used. Please refer to manufacturer installation and usage guide lines and adhere to them. Aluminum professionally built high back racing seat required. No plastic, etc. Padded headrest required. Seat must be securely bolted to a mount assembly that is an integral part of the roll cage. 6 bolts min no smaller than 3/8” diameter bolts. A five (5) point safety harness, with quick release is mandatory! 3” wide lap belt, 2” or 3” shoulder belts, and a 2” submarine belt. All belts shall be attached to roll cage using minimum 3/8 grade 8 hardware and safety cables. Loop around belts ok. Cotton harness components prohibited. Safety harnesses/seat belts may be no more than three (3) years old. Must have manufacture date. Snell SA2010 or SA2015 helmet required. Full face helmets with Lexan face shield recommended. Nomex helmet, skirt, and Nomex covered chinstrap highly recommended. A HANS or Hutchens type head and neck restraint device is strongly recommended; minimum of a neck roll required. Window net mandatory! Minimum 1” webbing with release at top only. It is required that all window net releases be updated to the quick release seat belt type with releases located and facing the outside of the car. No close mesh off-road type allowed. Fire suit mandatory at all times. Two layer one piece suit recommended. Two piece suit ok. Single layer proban suit ok with nomex underwear. Approved racing gloves mandatory. No welding gloves, gardening gloves, etc. Approved racing shoes mandatory. Eye protection is mandatory and must be in proper place at all times. Current test date (2 pound minimum) fire extinguisher to be installed in the car within drivers reach while strapped in. Steel mounts only, no plastic. All cars will be required to have in their pits a minimum of one five pound, Halon or dry chemical fire extinguisher. This is to be visible to tech officials and all crewmembers. All crew members must be made aware of this location, and knowledgeable in the use of the fire extinguisher. Car and driver will be required to make safety rule violations comply PRIOR to racing any event. The use of a two-way radio with a spotter and/or pit crew is mandatory. Irwindale Speedway radio frequency is 466.0375. It is highly recommended that all racers monitor this frequency during all races. This will speed up getting cars lined up during yellow flags.
APPEARANCE AND IDENTIFICATION – All cars are to be neatly and brightly painted. Numbers will be a minimum of 18” on the roof and both door panels. Numbers on the roof to face toward scoring tower (flag stand). No aluminum foil type lettering. Numbers assigned to car will be displayed on the top right front of windshield, 3” minimum. Drivers first and last name to be placed above each door, on the roof in 3” letters minimum. No duplication of numbers, additional letters such as “X”, “Y”, “and N” are not to be used. Advertising or names on the windshield is not permitted. This will be reserved for a series sponsor. Advertising that is deemed to be unsuitable/offensive, will not be allowed. Decision of Tech Officials will be official. Series sponsor decals, if any, must be placed on designated location of car to be eligible for awards. This is to be completed PRIOR to competing in any event.
ELECTRONICS – No electronic monitoring computer devices capable of storing or transmitting information except tachometers. No digital gauges, timing retard controls or oxygen sensors allowed. No electronic traction control devices allowed.
AS OF 4/27/21, THESE RULES SHARE DIRECT COMMONALITY WITH ORANGE SHOW SPEEDWAY AND HAVASU 95 SPEEDWAY MINI STOCK DIVISIONS. IRWINDALE SPEEDWAY RESERVES THE RIGHT TO ALTER THESE RULES AT ANY TIME IN THE INTEREST OF SAFETY AND COMPETITION.