Mini Stock Rules
**ADAPTED FROM THE 2015 “MINI STOCK MAYHEM” RULEBOOK**
RULE BOOK DISCLAIMER: The rules and/or regulations set forth herein are designed to provide for the orderly conduct of racing events and to establish minimum acceptable requirements for such events. These rules shall govern the condition of all events, and by participating in these events, all participants are deemed to have complied with these rules. TRACK OFFICIALS shall be empowered to permit any and all deviation from any of the specifications herein or impose any further restrictions to keep the competition close. Any interpretation or deviation of these rules is left to the discretion of the TRACK OFFICIALS, their decision is final.
– Minimum Age for Drivers is Fourteen (14) years old
– Under 16 must have officials approval and parent’s consent form filled out prior to on track.
– Drivers may have experience from any other level of racing and still be allowed to participate.
– Any 1960 and later with a maximum wheelbase length of 102 inches.
– Front or rear wheel drive car or truck. No all wheel drive cars.
– No 2 seaters.
– No convertibles.
BODIES, ROLL CAGE and CHASSIS:
– All chassis must have come stock with a 4 cylinder engine of any version.
– Any stock or aftermarket body, including straight sided dirt, made from fiberglass, aluminum or steel allowed. Open wheel type must submit photos for approval and will be allowed for one race maximum if approved.
– Full windshield required. Side and rear glass optional. Sunroofs must be covered with minimum 22 gauge steel. Roof escape flaps as required at Bowman Grey are allowed.
– All doors must be bolted, welded or riveted shut.
– All hoods must be sealed to the fenders, cowl (or windshield) with no more than 1inches gap. No hood scoops, holes in hood or anything else funneling air to the carburetor.
– At least four positive fasteners must be used to hold hood and trunk, OEM hinges may account for two of these four total.
– Must have full firewalls front and rear with no holes, completely sealed, 22 gauge steel minimum for refabricated sections. No combustible materials to fill holes.
– Must have factory floor pan from front firewall vertical section above transmission tunnel behind motor to front mount for back seat.
– Inner structures of fenders, wheel wells, strut towers and trunk floor may be removed.
– Rear spoilers will be a maximum of 5 inches tall and 54 inches wide. Highest point of rear spoiler must be at least 10 inches lower than the highest point on roof. Rear spoilers may have to be shortened or removed to meet the 10 inch minimum described.
– Spoilers must be mounted at the back of the trunk area near tail
– Complete 6 point center section and rear down bars of roll cages must be 1- 1/2inches minimum diameter and .090inches inch wall thickness minimum. No muffler pipe or crimped muffler bends in main cage.
**The tech person will have the power to disallow any car with compromised structural integrity or protruding parts that may be dangerous to a competitor.**
– Minimum of 4 door bars on driver side, with 1/8 inch metal plate must be welded to the driver’s side door bars so nothing can enter the driver area. Minimum of 3 door bars on passenger’s side.
– All perimeter bars and bumper bars must be shaped with safe and reasonably rounded ends to eliminate puncturing other driver’s, doors, tires, fuel cells, etc. No push bars outside of front bumper cover.
– All bars within driver’s reach must be padded.
– Steering quickner allowed.
– Quick release steering wheel suggested.
– Aftermarket pedals allowed, may be relocated.
– All glass except windshield must be removed. No plexiglass windshields. Lexan or glass windshields allowed. For glass windshields, only safety- glass laminated allowed. Two vertical braces at least 1 inches wide x 1/8 inch thick required on windshield.
– Side view and rear view mirror allowed.
– Side vents for driver cooling allowed.
– Brake air ducts allowed.
– Track Width maximum 63 inches front & rear, measured from center of tire to center of tire.
– May use any size, type or arrangement of wheel spacers to make ride width maximum.
– Wheelbase must be within +/- 1 inch of stock factory length for car model claimed. Left and right sides of car must be within 1 inch of length of each other.
– All weight & weight percentages are measured with driver & car in race trim.
– Advertised engine size in cc and left side weight percentage to be located on the hood, so tech can read it when you roll on to the scales.
– 35 lbs of lead may be added to the center of fuel cell, or 5 gallons of fuel added for post race weigh- in. Maximum of 35 lbs or 5 gallons regardless of fuel cell size or number of laps run.
– All cars will weigh one pound per cc after race and a minimum of 2000 lbs.
– All weight and engine size specs must be written on hood.
– All rule infraction weight or left side weight percentage penalties must be posted on hood to support post race protest procedures.
– All Ford engines, minimum weight 2300 lbs. 1 lb. per cc above 2300cc. Example 2500cc = 2500 lbs.
– Toyota 20R block with 22R head must weigh 1 lb per cc.
– Ford 2300 head on 2000 block must weigh 2300 lbs.
– Ford Pinto/Lima style engine with 1.50” intake and 1.75” exhaust valves may compete at 2300 lbs.
– Maximum left side weight is 55% of the total weight (see weight penalties for exceptions)
– No dislodged parts can be added back to the car after the feature race to make weight
– All lead must be in blocks and painted white with car #. All weight must be securely bolted with nylocks or double nuts.
– Any chassis design or car make that has an obvious advantage over any other may be subject to weight percentage and weight additions for the sake of close competition.
– Weight penalty form “MUST” be filled out “BEFORE” car can run practice and main event and
transponder must be on car during practice or the car won’t be able to qualify and must start in rear.
– Any Ford running longer than a 5.7” connecting rod, 2% left side weight penalty.
– Any competitor running the two ring piston assembly, 2% left side weight penalty
– Any competitor running the 7mm valve kit, 2% left side weight penalty.
– Combinations of above listed weight penalties will be enforced, example a competitor running a 6 inch rod with the 7mm valve kit will have a maximum of 51% left side weight.
– All engines must use stock OEM parts with only the exceptions stated here. 4 cylinder piston engines only. No Rotary engines. You may interchange engines and chassis within your manufacturer line but not across makes. Example: Any Ford in a Ford but no Toyota in a Ford. No turbochargers or superchargers.
– Engine must be installed in stock location. For engines interchanged between chassis of the same make, there is to be no less than 1 inch between back section of cylinder head and vertical plane of stock firewall placement.
– Stock O.E.M. or solid motor mounts allowed.
– Must be stock O.E.M. production only, no aftermarket blocks.
– No block is to be coated, polished or any machine work except what is listed here.
– Minor machining to block for aftermarket rod clearance allowed.
– Blocks can not be offset bored but may be sleeved with original bore centerline
– Stock O.E.M. type rod, camshaft and crankshaft bearings.
– No maximum overbore.
– Aftermarket pulleys and waterpump allowed.
– Crankcase evacuation system to header allowed.
– Aftermarket oil pan allowed.
– Must be stock O.E.M. cast or steel, no aftermarket such as Scat, Lunati, etc. allowed.
– Stock O.E.M. stroke of crankshaft being used must be maintained within +/- .010inches.
– No lightening or knife edging of throws or counterweights.
– May polish between #4 rod journal and #5 main journal surface areas for the purpose identifying cracks more easily and eliminating surface stress risers, not to lighten.
– Engine balancing allowed, must be done in a standard production manner.
– Stud girdle kit allowed on main bearings.
– Crankshafts may be interchanged among blocks within the same make with no machining needed. Direct fit applications only.
– CC’s on hood must reflect correct bore and stroke combination. Engines will be P&G tested regularly.
– No 2.5 crankshafts allowed in Fords.
– Any steel aftermarket rods allowed.
– Max length for Ford is 5.7 inches.
– Max length for Toyota is 5.7 inches.
– Max length for any other model is 5 inches.
– May polish stock OEM rods.
– No hollow aftermarket rods.
– Toyotas may use H- beam rods.
– Minimum 1.950” diameter rod journal diameter for Fords.
– Any rod bolt allowed.
– Any Ford with rods longer than 5.7 inches may compete with maximum 53% left side weight.
– Any flat top piston with any number of ring glands allowed, must have zero deck height.
– No gas porting.
– Any steel wristpin allowed, no titanium pins.
– Any O.E.M dome piston engine may run any dome piston. The flat part of the dome piston may extend 0.010 inches above deck height.
– Any style piston rings allowed. Minimum 3 rings per piston.
– 2 ring piston assembly may compete with maximum 53% left side weight.
– All engine bearings must be stock O.E.M. type sleeve bearing, No roller bearings allowed.
– No titanium fasteners permitted, any other fastener type allowed.
– Head and main bearing studs allowed.
– Any brand allowed. No o- ring style sealing allowed in place of head gasket.
– Must be stock O.E.M. heads, No aftermarket heads allowed.
– Heads may be interchanged on blocks within same make in direct fit applications. Crossbreeding within same make is allowed. Ex. Toyota 22R head on 20R Block or Ford 2300 head on 2000 block. No machining allowed to do so, direct fit applications only.
– Angle milling allowed.
– Two valves per cylinder maximum.
– Stainless Steel O.E.M. configuration valves and swirl type allowed.
– Valve stems may not be smaller diameter than stock for head being used.
– Any engine with valve stems smaller than stock diameter may compete with maximum 53% left side weight.
– No titanium valves.
– 7mm valve kits permitted, cannot be over the O.E.M stock valve size.Competitors subject to 2% left side weight penalty if choosing to run 7mm valve kit.
– Valves may be Back Cut 30 Degree Maximum.
– Valve stems may not be canted in heads.
– No interior de- burring, polishing, extrude honing or acid porting allowed.
– Ports must be stock as cast from OEM.
– Lifter bore may be machined for solid adjusters.
– O.E.M or stainless aftermarket valves must retain stock head diameter.
– Any steel or stainless steel retainer/keeper allowed. Valve job angles optional.
– Any valve spring combination or design.
– O.E.M valve diameter stock size for cylinder head used.
– Ford Pinto/Lima style engine with 1.50” intake and 1.75” exhaust valves, see weight section for requirements.
– Reinforcement on cam boss allowed.
– Late model stock style bowl cut allowed. 1 angle under the seat, 1 inch maximum depth of cut but do not touch the valve guide. No blending of bowl cut to ports or rounding edges that bowl cut creates.
– No roller cam followers allowed except on GM 151 engines.
– Cam buttons allowed.
– Any type of valve job allowed. Ex: 3 angle
– Any aftermarket hydraulic or solid cam allowed, any lift without weight penalty.
– Adjustable cam gear allowed.
– Stock O.E.M. steel or double roller timing chain and gears with hex adjustment allowed.
– Anti- pump up hydraulic lifters allowed.
– No lightweight push rod.
– Only stock OEM rocker arms and lifters that came OEM in the head being used.
– Lifter bore may be machined to allow for solid adjusters.
– Oil return screens allowed.
– Lifter valley baffles are allowed.
– Lifters must be stock sizes for head being used.
– Roller rocker arms allowed on GM engine only.
– Any valve spring retainer and shim allowed.
– Stock O.E.M. factory intakes with factory part number.
– Fuel injection intakes allowed.
– No hi- performance aftermarket intake manifolds.
– No porting, polishing, coating, dipping, port matching, etc.
– Intake may only be modified to accept carburetor, no other modifications allowed.
– Carburetor adaptor plates must not protrude down into plenum.
– All parts must be mass produced items available as stock production over the counter parts. No special test or marine type parts. Only North American distributed intakes on domestic. Asian allowed on Japanese makes only.
CARBURETORS, SPACERS and ADAPTERS:
– Holley 350 CFM # 0- 7448, # 0- 80787- 1 or Holley 500 CFM # 0- 4412, # 0- 80583- 1.
– Choke hardware removal allowed.
– All vacuum ports must be plugged.
– 2 Gaskets @ .065 max ALLOWED.
– Any carburetor adapter or spacer, 1.5 inch thickness maximum.
– 2 circular holes, 1 oval hole, beveled and/or tapered allowed.
– No modification to carburetor for mounting.
– 350 CFM 30 cc Accelerator pump ONLY.
– Carburetors will be checked per NASCAR Late Model Stock guidelines
– No polishing, grinding, or machine work.
– No base plate modification.
– No drilling of additional holes.
– Boosters may be changed.
– No booster modification to size or shape.
– Height and location of the boosters must remain per factory specs ONLY.
– All boosters must maintain OEM outside diameter ONLY.
– No venturi area to be altered or reshaped in any manner.
– No removal of casting ring.
– No modification to allow additional air to be picked up below the opening of the venturi.
– No altered gaskets, base plates, or drilling holes into the carburetor.
– No butterflies to be thinned or tapered.
– Idle holes may be drilled in butterflies.
– Screw ends may be cut even with shaft, but screw heads must remain standard.
– No shafts to be thinned or cut at all.
– Accelerator pump discharge nozzle may be changed.
– Power valve may be changed.
– Jets may be changed.
– No outside air to be pulled through the carburetor other than through the venturi.
– All cars must have a metal air cleaner housing.
– Aftermarket air cleaner up to 14inches diameter x 5inches tall max allowed.
– Paper element or K & N type allowed.
– No funneling of any air to the air cleaner or carb.
– Base of air cleaner must be below choke horn.
– No carb hats, baffles, etc.
– Top and bottom of air cleaner housing must be the same size.
FUEL & FUEL SYSTEM:
– Track fuel only.
– No additives.
– No fuel cooling devices.
– Fuel Cell: 12 Gallons max.
– Fuel cell must be mounted in a can made of at least 22 gauge metal.
– Fuel cell must be mounted in center of trunk area between the frame rails. No more than 2” deviation from center of rear treadwidth.
– Fuel cell must be protected with a sufficient amount of structure, including a bar below and to the rear of the can.
– Fuel cell venting high and to the driver’s side recommended.
– Fuel Pump: HP mechanical or electrical allowed. Must have roll over valve/switch if electrical.
– Must be approved by tech person.
– Fuel will be checked randomly.
– Battery must be securely mounted and enclosed to guard the driver from spills or explosions.
– Batteries may be mounted in trunk or through floorboard but no lower than frame rails.
– Only 12 volt electrical systems allowed.
– Standard or electronic distributor may be modified for reliability only.
– Stock type coils only.
– MSD, ACCELL, MALLORY etc., internal parts, coils or modules are allowed, stock style only.
– No magnetos.
– No multiple spark discharge boxes or systems allowed.
– Point type allowed.
– No full aftermarket distributors.
– No adjustable timing controls.
– No traction control devices
– All wiring in car must be securely insulated and fastened.
– Any spark plug wires allowed.
– Any spark plugs allowed.
– No dual point distributors allowed.
– Mels distributors allowed.
**NO ANTIFREEZE – $100.00 FINE FOR 1ST OFFENSE**
– Stock cooling system only in stock O.E.M. location
– Any radiator allowed.
– No antifreeze, may use Water Wetter type products.
– Electric fans allowed.
– Overflow hose must be routed to base of windshield on passenger side to alert driver in case of overflow.
– Fabricated mounting for radiator allowed, must be mounted between frame rails.
– Any stock or aftermarket exhaust manifold or header allowed.
– 4 into 1 and Tr- Y style allowed.
– Exhaust pipes must route to behind the driver’s seat, and must extend to the outer edge of the car.
– No exposed pipes in driver’s area.
– Exhaust may run through the inside of the race car if totally boxed, sealed and approved by tech person.
– No pipes turned down.
– Mufflers allowed.
– Crankcase to exhaust evacuation systems are permitted. Only quality check valves will be permitted.
– Stock type wet sump only.
– External oil filter and coolers allowed, must remain under the hood with steel braided hose and AN type fittings. No rubber hose or hose clamps allowed.
– No dry sump or accu- sump systems.
– Any race type oil pan allowed.
– Screen kits in oil return system allowed.
– Oil pan baffles preventing oil from flowing away from the oil pump pick- up allowed.
– No crank scrapers.
– Windage trays allowed.
– All chassis suspension mounting points must be stock OEM. All left to right, height and “X” measurements must be within 3/4 inch.
– Front lower control arms must be equal length left to right.
– Rocker panels may be removed and replaced with square tubing.
– All frames must be stock, Unibody frames may be tied together end to end half way max on frame rails.
– Firewall, frame rails, floorboards and suspension mounts must remain intact from center of front wheels to center of rear wheels in a way that proves there have been no chassis mounting point, length or width modifications.
– You may patch floor pan if it’s rusted or has holes. Do not cut out and replace entire pan.
– Entire floor of trunk may be removed.
– No pushbars extending outside of bumper covers.
– Frame may be notched for oil filter and fuel pump clearance.
– Adjustable rear shackles and slider blocks allowed on leaf springs.
– Front eye of leaf spring must remain in stock location.
– Adjustable coil spring spacers, wedge bolts, adjuster cups, spring rubbers, weight jacks, lowering blocks allowed.
– Heim joints are allowed on sway bar and in place of tie rods for bump steer correction.
– Rear panhard bars allowed only on cars which came stock with them. May be adjustable from under car only and with positive bolt pattern, no jack screws.
– Solid engine & transmission mounts allowed.
– Aftermarket pedals allowed and may be relocated.
– Single or double master cylinders allowed.
– Brake adjusters, flow control and metering valves allowed but MUST BE OUT OF DRIVERS REACH AND CAN NOT BE USED DURING RACE.
– Max sway bar diameter is 1 5/16″ or 33 mm.
TRANSMISSIONS, FLYWHEELS and CLUTCHES:
– Automatic or manual allowed. All gears must be functional from driver’s compartment.
– Automatics transmissions: manual shift kits allowed. Reverse shift patterns allowed. Internal modifications for durability only. No trick or lightweight internal parts, O.E.M. factory only. Torque converter must be stock O.E.M. size. Must be factory O.E.M. stall speed. No stall or hollow converters. No aftermarket Hi- Pro converters. No valve or any mechanism to transfer transmission pressure allowed. Neutral safety switch must be functional at all times. Modified transmission oil pan allowed. Transmission oil cooler size and placement is optional. Cooling lines must have no more than 12inches of high- pressure rubber tubing. Aftermarket flex plate allowed.
– Manual transmissions: All gears must be functional from driver’s compartment. Three (3), (4) or (5) speed transmissions.
– No aluminum flywheels permitted.
– Any type flywheel and pressure plate combination with a minimum weight of 23 lbs. Weight will include flywheel, clutch disc, pressure plate and bolts.
– No aftermarket Hi- Pro clutch packs such as 10,000 RPM, RAM, Center Force, etc. permitted.
– Reinforcement in area of floorboard for safety is required.
– No aftermarket transmissions, must be factory standard production only.
– No lightening of internal rotating components in transmission.
– Standard one (1) piece, minimum diameter 2 ½ inches. Steel only.
– Must be painted white with car number on it.
– Drive shaft safety loops front and rear mandatory.
– Any car or truck rearend, interchanging allowed within make.
– Mounts on interchanged rearends must match stock rearend to exact OEM measurements. A OEM stock rearend for your chassis may be required for verification.
– 9” Ford rear ends allowed.
– No floater rearends.
– Any differential: open, welded, full spool, mini spool, locker, limited slip or helical gear types allowed.
– No quick change rearends.
– Any gear ratio allowed.
– Rearend components may be lightened.
– No cambered rearends, +/- 0.4 degrees maximum deviation.
– Aftermarket lower trailing arms allowed, must be OEM stock length.
No heim joints on lower trailing arms.
– Any aftermarket axle allowed.
– See Chassis rules above for panhard bar specs.
– OEM style third link or upper trailing arms may be aftermarket and/or adjustable length. Mounting holes at chassis and rearend housing must be stock OEM location.
– Stock OEM style suspension that came on your chassis.
– Stock style control arms only. No aftermarket a- arms.
– Stock style upper a- arms may be shortened or lengthened for camber/caster adjustment.
– No upper a- arms added in place of stock strut design.
– Any bushing allowed.
– Lower a- arms may be interchanged within same make. Must meet maximum ride width rules.
– May lengthen or shorten stock type lower a- arms on Toyotas only. Must be equal length left and right.
– Strut rods on lower control arms (such as Pinto and Toyota) may be adjustable in length but retain same mounting points.
– OEM Sway bars only, no splined type. 1 ¼” or 33mm max diameter. Mounting optional. End link design optional. May be adjustable on both ends.
– Any upper strut plate/connection may be used in place of strut tower.
– Lemans bar between strut tower allowed.
– Steering quickeners allowed.
– Any camber and caster settings allowed.
– Spindles, rotors and calipers must be OEM but may be interchanged within different year models or versions of your same chassis.
– Disc brakes may be interchanged with drum brakes within your same make.
– Steering box and rack may be interchanged among same make.
– No aftermarket spindles. Spindles may be strengthened.
– Steering arms may be modified for bump steer correction.
– No bump stops.
– Aftermarket power steering pump allowed.
– Brake air ducts allowed.
– Brake hats allowed.
SHOCKS, SPRINGS and STRUTS:
– 1 steel bodied shock or strut per wheel, must be mounted in factory location.
– Rubber grommet type shock mounting style may be replaced with heim joint.
– Aftermarket racing shocks allowed. No aluminum bodied shocks.
– No re- valveable or Schrader valve type with external reservoir.
– Strut type can be adjustable and/or replaceable cartridge- in- housing type.
– Any aftermarket coil spring allowed. Rates optional. Spring dimensions are optional.
– At least one end of springs and shocks must be in OEM location.
– All heights are measured with the driver in race trim.
– Front spoiler minimum of 4 inches.
– Center of the crankshaft bolt to the ground, minimum of ten (10) inches.
– Frame height minimum of four (4) inches, measured at the frame rail.
– Outer rocker panels minimum of (4) inches.
– Fuel cell and or fuel cell frame: minimum eight (8) inches from lowest point.
– Oil pan minimum of four (4)inches.
WHEELS AND WHEEL SPACERS:
– 8 inch maximum width with minimum of 2 inch backspace.
– Thirteen inch diameter only.
– Steel only.
– Any wheel stud diameter and length.
– Offsets on all 4 wheels do not have to match.
– No pressure relief valves.
– No wheel weights.
– May use any size, type or arrangement of wheel spacers to make ride width maximum.
– Helmet: Snell 95 or better with DOT tag.
– Flame retardant driving suit, gloves with SFI tag.
– Neck Collar or head & neck restraint device / system (R3/HANS/HUTCHENS) recommended
– 5- point racing harness with SFI tag. Not older than 24 months.
– Aluminum racing seats only.
– Approved window net required.
– Racing shoes recommended.
– 1ea 2- 1/2 lb fire extinguisher with a dial, must be located within reach of driver.
– Master kill switch must be mounted within easy access of driver and also safety crew member from outside of car.
– A driver shall not permit any person to ride in or on any racecar at any time.
– If your car does not pass pre-race safety tech, you can not practice or race until it is corrected.
– Radios allowed.
– Transponders mandatory. Must be mounted near or on rear axle.
– TRACK OFFICIALS must approve all racecars to compete and their decisions are final.