2024  B MODS RULES AND REGULATIONS  *Denotes Changes for 2024    Printable Version PDF

1. *FRAME
   OEM complete, 1964 or newer, perimeter American rear-wheel drive passenger car frame only. No sports car frames. No Jeep, Bronco, etc., or four-wheel drive frames. No front-wheel drive frames. Frame must be full and complete, cannot be widened or narrowed, and must be able to support roll cage on both sides, except: weight jack in original center line of spring tower allowed; frame may be cut a maximum 36 inches forward from center of rear end housing; horns may be removed in front of steering box and notched maximum one inch at bottom for tie rod clearance; front cross member may be notched and boxed for radiator and/or steering clearance; maximum seven-inch wide opening in side of spring tower for spring removal. Maximum two-inch wide by four inch tall frame stiffener may be welded directly to outside of left side frame rail. Left top frame rail may be removed inside cockpit. Minimum wheelbase 108 inches, maximum 112 inches, maximum 1 inch difference from side to side. Maximum overall width (front or rear) shall not exceed 78 inches from outside of tire to outside of tire. For cars using OEM rear suspension design, rear of frame behind rear tires no further forward than one inch behind factory seam, may be replaced with two inch by three inch steel tubing with 0.095 inch wall thickness. No part of frame or body can be lower than 4 inches or higher than 7-1/2 inches from the ground except front cross member and rear underslung.
   
   
2. ROLL CAGE
   Must consist of continuous hoops, minimum 1.75 inch O.D. tubing, with; a minimum wall thickness of 0.095 inch for main cage, frame-mounted in at least six places. No brazing or soldering allowed. Must consist of a configuration of front, rear and top hoops, connected by tubing on sides or side hoops. Driver's head must not protrude outside cage with helmet on. Roll cage must be securely supported and braced with minimum one cross bar in top halo. Foot protection bar required. Main cage no further forward than rear of engine. All bars forward of cage must be lower than hood.
   
   
3. DOOR BARS
   All driver side door bars and uprights must be minimum 1.50 inch O.D., and 0.083 inch wall thickness. Minimum three driver side door bars, parallel to ground and perpendicular to driver, and welded to front and rear of roll cage. Passenger Side must have at least one cross door bar, horizontal or angled, minimum 1.25 inch O.D. and 0.083 inch wall thickness, and one top horizontal door bar, minimum 1.50 inch O.D. and 0.083 inch wall thickness. Steel door plate, 18 gauge or 0.049 inch minimum thickness, must be securely welded to outside of door bars and cover area from top door bar to bottom door bar and from rear hoop down-post to 5 inches in front of seat. Must be visible for inspection.
   
   
4. *BODY
   No unapproved composite or plastic body panels allowed. Approved composite doors, rear quarter panels (FMVSS302 burn rating) roof rock guard and hood scoop allowed. Body and interior deck must be same width, front to rear, and parallel to OEM frame. Aluminum nose panel must be flat (not dished). Maximum 2.250 inch side fins allowed on aluminum nose. PDTR plastic nosepieces allowed. Nose must be mounted in an approved manner and can extend no higher than front top of hood. Nose piece must remain inside confines of front bumper (exception is plastic valance) and be no lower than four inches below frame horns. Cooling holes allowed. Engine compartment must remain open (no side panels). Hood must cover radiator, be level or sloped down at front, enclosed and maximum two inches above interior deck at rear. Air cleaner top maximum 6 inches above hood. No panel in front of right door to engine compartment. No inner panels. No complete or half-car covers, rear tail cover allowed in pit area. Must have front and rear roof support posts. Driver and passenger side windows must have at least 12 inch opening (height and width,) measured at center of window, between lowest point at top and highest point at bottom. Solid sail panels only. Roof must be Fiber glass or aluminum, full size and rounded down in all directions. No dished roofs allowed. Driver roof hatch allowed. Maximum 1.5 inch rolled down rock guard allowed on roof front. Maximum four inch roof sides allowed. Maximum one inch ridge down sides of roof. Maximum one inch rear roof stiffener (must face down.) Sail panels may not extend ahead of back of seat. Rear spoiler allowed, maximum five inches in material height and maximum 66 inches wide. Spoiler may have maximum one inch rear stiffener, must be one inch or more down from the top. Maximum three spoiler braces allowed, must be mounted in line. Spoiler must be mounted within confines of spoiler braces. No additional fins, lips, wings, or vortex generators. Maximum four inch plastic skirting allowed on bottom of doors and quarters and nose. No reflective doors or quarter panels.
   
   
5. DRIVER COMPARTMENT
   Must have minimum three windshield bars in front of driver. Lexan or aluminum cowl panel in front of driver can be no wider than cockpit and no farther back than steering wheel. Minimum 0.125 inch aluminum or 0.060 inch steel, complete floor pan required. Aluminum high-back seat only and must be bolted in using minimum of 0.375 inch bolts, next to left side frame rail and ahead of rear tires. Bottom of seat can be no lower than bottom of frame rail. Driver must be sealed off from track, driveline, engine, fuel cell, canisters and pumps. Accumulators may not be mounted between driver and left side door bars. No driver adjustable devices allowed while car is in competition except brake adjuster. No mirrors of any kind.
   
   
6. FRONT SUSPENSION
   All components must be steel, unaltered OEM, in OEM location, and replaceable by OEM parts, except: tube-type upper A-frames with or without aluminum or steel cross shaft, and mounts can be moved; stamped steel OEM replacement lower A-frames; rubber, nylon or steel lower A-frame bushings, no offset or bearing type; one welded shock mount on lower A-frame; no screw jack type shock mounts; OEM or OEM replacement rebuildable ball joints allowed. Lower A-frames must be right and left, and of same design. Lower A-frame mounts and bolt holes on frame must be within OEM specifications. No sway bar. No suspension stops of any kind allowed.
   
   
7. STEERING
   No rack and pinion. All components must be steel, unaltered OEM, in OEM location. Exceptions are: outer tie rod end and adjustment sleeve may be replaced by a minimum 0.625 inch steel rod end and steel tube; spindles can be ground for brake caliper clearance only; unaltered, OEM replacement Pinto spindles; replacement spindle with Speedway Motors raised cast - part numbers 91034501 and 91034511; bolt on spindle savers allowed. Steel steering shafts and knuckles only; driver compartment steering may be modified, must be kept on left side. Spindles must be right and left, and of same design. Quick release required - steering quickener and steering wheel may be aluminum. Idler arm, pitman arm, and center link must match frame.
   
   
8. SHOCKS
   One steel, nonadjustable, unaltered shock per wheel. All shocks must completely collapse at any time. No external or internal bumpers or stops. One shock mount allowed, must be welded. No shocks allowed on screw jacks. No bulb-type, threaded body, coil over, air or remote reservoir shocks. Maximum 2.125 inch O.D. shock body. No Schrader or bladder type valve allowed. Front half may be shielded. Maximum 7 inch limit stroke on front shock, maximum 9 inch limit on rear shock. Can not preload or pin any spring.
   
   
9. SPRINGS
   One steel coil or multi-leaf (rear) spring per wheel only. Minimum 4.5 inches O.D., maximum 13 inch free height, non-progressive coils only. No torsion bars, air bags, inner liners, or spring rubbers allowed.
   
   
10. REAR SUSPENSION
    All components must be steel. No covers allowed. All mounts and brackets must be welded or bolted solid. Coil springs must remain vertical and over center line of rear end housing. No coil-over eliminators allowed. No chains, cables, or tethers. Exception is: solid safety chains securely mounted frame to axle housing only (cannot be mounted to any floating device), no springs or rubbers allowed. Rear shocks cannot be mounted on control arms. All rear control arms and panhard bars must be straight. Must utilize one the following designs.
    
    
    1. Aftermarket three link design requirements: Must use 16 inch minimum, 19 inch maximum lower control arms. Rear lower control arm must be centered under axle tube (1 inch tolerance) and bolted minimum 2 inches to maximum 5 inches from bottom of housing. Must use one upper control arm, solid tube only, centered over drive shaft front to rear (one inch tolerance). Must use minimum 23 inch panhard bar located behind rear end housing. Lower spring perch must be welded to rear end housing. Bottom of rear spring must remain within 0.75 inch of axle tube. Must use steel upper weight jack. No floating or bearing rear spring perches/cups allowed top or bottom. No suspension stops or adjustable underslung of any kind allowed.
    2. Multi leaf spring design requirements: Must use steel multi leaf springs with no additional suspension components besides one shock per wheel. Adjustable aluminum lowering blocks allowed.
    3. OEM stock design requirements: Rear cross member, control arm mounts and bolt holes on frame must be in stock location. All components must be unaltered, approved OEM, and match frame. Control arms cannot be altered in any way. Steel, rubber or nylon control arm bushings only. Springs must remain in stock location. Lower spring perch must be welded to rea rend housing. Must use steel upper weight jack.

11. REAR END
    Any steel approved OEM passenger car or truck non-cambered rear end (housing and carrier) allowed. Safety hubs (floater) allowed. All components must be steel, except lowering blocks, axle and U-joint caps, and drive flange. One inch inspection hole in housing is required.Solid steel axles only. No quick change devices of any kind. One piece drive flange only. No torque dividing mini spools or differentials. Ring gear, center section and yoke cannot be lightened.Rear shocks must be behind rear axle.
    
    
12. BUMPER/RUB RAILS
    Steel only. Bumpers must be used both front and rear at all times and welded, or mounted with minimum 0.375 inch bolts. Rear bumper must be constructed of solid square, or minimum 1.25 inch O.D. tubing with 0.095 wall thickness maximum of six inches beyond rear deck, no wider than five inches outside of rear frame rails. If wider than five inches outside rear frame rails, must be bent forward 90 degrees, or constructed in a loop design. Must have at least one upright, minimum 1.25 inch with 0.065 wall thickness, from bumper to fuel cell guard. Two bar front bumper must be minimum 1.25 inch O.D tubing with minimum 0.065 wall thickness (maximum 0.095 inch) mounted frame-end to frame-end, no wider than width of material outside frame horns and with bottom loop parallel to ground. Top bar must be directly above bottom bar, minimum 6.5 inches apart, measured center to center. All bumpers and rub rails must be capped with no sharp edges.
    
    
13. TIRES/WHEELS
    Must use unaltered Hoosier race tire G60-15. No chemical softening or conditioning of tires. Tires may be ground, straight grooved or siped on the tread face only of the tire. May not extend past factory edge line of tire. Tire reconditioning subject to approval of technical inspector. No recaps. All wheels must be 3 or 4 inch backspace. No wheel adapters allowed. No spacers allowed. No bleeder valves allowed. May use beadlock on right rear only. External, steel bead lock on right rear only and it cannot make wheel any narrower than 8-inches and no wider than 8.75 inches. Must use only steel bolts. Foam type or plastic outer mud cover allowed on right side wheels.Wheels covers must be bolted. Dzus fasreners are prohibited.Inner mud cover allowed on left wheel only. Must use minimum one inch O.D. steel lug nuts.
    
    
14. BRAKES
    Must be steel approved OEM, operative four wheel drum or disc. Must maintain minimum OEM dimensions for hubs/rotors and calipers cannot be lightened. No oil bath front hubs. Bolt pattern may be changed. Larger studs allowed. Rear rotors may be aftermarket, 0.810 inch thickness (new). Vented solid surface rotors only, no scalloped or ceramic coated rotors. No brake shut-off or pressure sensitive devices. One proportioning device allowed, front to rear only. Brake lines must be visible. Rear caliper brackets must be welded or bolted solid to rear end housing.
    
    
15. EXHAUST
    Round tube headers only. All primary header tubes must enter directly into one collector, at same point, at end of header. Collector and turn down length maximum 19 inches. Non stepped, painted headers only. No heat wrap. Mufflers mandatory at all times car is on the track. 95-decibel limits at 50 feet from car. All exhaust must go through mufflers, two per car, and one per header. No merge collectors, extensions, inserts, cross overs, cones or balance tubes. No exhaust sensors. No pan evac systems allowed. Loss of muffler will result in disqualificationfrom that race.
    
    
16. FUEL SYSTEM
    Mechanical OEM type push rod fuel pumps only. Racing fuel cell required, maximum 32-gallon capacity must be in minimum 20 gauge steel container. Cell must be securely mounted behind rear axle, between rear tires, minimum of four inches ahead of bumper, minimum of ten inches above ground. Must mount with minimum one inch square tubing or two 0.125 inch thick solid steel straps, two inches wide around entire cell. All cell mounts must be steel, securely welded to frame/cage. Protective tubing must cover rear and extend past both sides of cell. No part of cell shall be lower than protective tubing. Fuel cell vents, including cap vent, must have check valves. If fuel cell does not have aircraft style positive seal filler neck/cap system - a flapper, spring or ball type filler rollover valve is required. Pick-up must not be underneath fuel cell. Limit of one fuel filter. No cool cans. Air cleaner top, stud and base cannot direct air into carburetor. No top flow housings or cold air boxes. Maximum .100 inch thick carburetor gaskets on all engines.
    

1. GM CRATE ENGINE: May use Holley 4-barrel carburetor, all components (float bowls and main body) must be Holley manufactured. Metering blocks and base plate may be billet aluminum non-Holley. No aerosol style carburetors allowed. May use Speedway Motors Part # 545-64940 or Moroso part #64940 carburetor spacer on crate.
2. *OTHER ENGINES: Must use naturally aspirated, unaltered 500 c.f.m. Holley carburetor, part # 0-4412 or 4412 SA (aluminum casting no. L6R199B and metering block no. 707). Float bowl must face forward. Any adapter, maximum 1 inch thick. No throttle bore adjustable carburetor spacers.  

17. FUEL
    Gasoline only. Racing fuel allowed. No E85. NO nitrous oxide. NO performance-enhancing additives.
    
    
18. WEIGHT
    Minimum weight limit of 2,500 pounds, no tolerance, after race with driver in car. No weights and/orloose objects in driver compartment or outside body. Weights must be securely mounted to frame or roll cage and painted white with car number on it. Must be attached with at least two 0.5 inch bolts. No titanium, magnesium or carbon fiber products. Exceptions are: carbon fiber rock guard and hood scoop. Steel fasteners only. Loss of weights will result in disqualification from that race.
    
    
19. BATTERY/STARTER
    One 12-volt battery only, must be shielded and securely mounted between frame rails, and positive terminal covered. Starter must bolt on block in OEM location and directly engage flexplate/flywheel. No lithium battery.
    
    
20. *ELECTRONICS
    No transmitting or listening devices, timing retard controls, or digital gauges (including tach). No electronic monitoring computer devices capable of storing or transmitting information except memory recall analog tach. 12-volt ignition system and OEM HEI distributor only. Ford/Chrysler may use HEI distributor. No billet distributors or crank triggers. Ignition rotor, cap, coil and module must remain OEM appearing. No additional ignition accessories allowed. Crate engine must use MSD #8727CT rev-control and 6,200 rpm. Other engines must use #8727CT rev-control with a 6,600 rpm. All components must be out of reach of driver, but with rev-control easily accessible facing up or out for inspection. All wiring must be visible for inspection. OEM type alternator with internal regulator allowed. No electronic traction control devices. Only gauges allowed are analog oil pressure, fuel pressure, brake bias, water temperature and tach. Kill switch required within easy reach of driver and clearly marked "ON" and "OFF".
    
    
21. TRANSMISION/DRIVE SHAFT
    Only OEM production transmissions allowed. No 'in and out' boxes, or quick change devices allowed. Functioning shift levers must be in OEM location. One steel or aluminum OEM style/size flywheel or steel OEM style/size flexplate allowed. And must be bolted directly to end of crankshaft. 

1. OEM Case Manual Transmission
   Must have a standard OEM case and have a working 7.25 inch minimum diameter, steel and/or aluminum, single or Multi-disc clutch and pressure plate bolted directly to flywheel/flexplate. Must use explosion proof steel bellhousing with one hole for throwout bearing lever or hose, must be 270 degrees around top of clutch and flywheel area. Hydraulic clutch pedal allowed with manual transmission. All gears must be working.
2. Automatic Transmission
   Must remain in OEM or OEM replacement case, with a functioning OEM appearing pump. Aluminum OEM bellhousing may be replaced with aftermarket explosion-proof steel or aluminum bellhousing. Original OEM bellhousing must have approved scattershield constructed of minimum of 0.125 inch by three inch steel, 270 degrees around flexplate. Splined drive flange coupler or torque converter (10 inch minimum) only. No bump starts allowed. All gears must be working.
3. Drive Shaft
   Minimum two-inch diameter steel drive shaft and must be painted white. Steel slip-yokes only. 360 degree drive shaft loop required and must be constructed of at least 0.25 inch by two-inch steel, or one-inch tubing, mounted six inches back from front U-joint.

22. ENGINE COMPARTMENT
    Rear of engine (bellhousing flange) must be mounted at least 72 inches forward from centerline of rear axle. Engine offset must be kept within 2 inches of centerline of front cross member with engine level. Minimum 11 inch engine height from ground to center of crankshaft. V-belt aluminum or steel pulleys only. Radiator must be mounted in front of engine. No vacuum pump, oil coolers, remote oil filters, oil pan vents,or sprinkler systems. Use of antifreeze is prohibited.
    
    
23.  ENGINE SPECIFICATIONS
    

1. CRATE ENGINE: Must use unaltered sealed GM #88958602 or #19258602 crate engine.
2. OTHER ENGINES: All engines must be able to be used in conventional passenger car without alterations. External engine casting and threaded holes cannot be altered.
   
   
1. BLOCK: OEM steel passenger vehicle production block only. No GM Bowtie, Ford SVO or Chrysler W components allowed. GM approved block numbers are; 10105123, 10066034, 3892657, 3914660, 3914678, 3932388, 3932386, 3956618, 3970000, 3970006, 3970010, 3970014, 10066033, 10066036, 10243880, 14010207, 14010209, 14010287, 14016376, 14016379, 10054727, 14088528, 14088548, 14088552, 14093638, 14101148, stroke must match block. No 400 or larger cubic inch parts allowed. Maximum cubic inches: GM 361, Ford 363, Chrysler 370. Maximum compression ratio is 9.0 to 1, no leeway. Flat top or dished pistons only, no gas-ported pistons. OEM or OEM appearing replacement steel crankshaft only, cannot be lightened. No aerowing, bullnose, knife edge, undercut or drilling of second or third rod throws. OEM or OEM cast appearing replacement steel rods only, GM 5.7 inch, 6 inch, or GM Vortec rod part #10108688 allowed. Cap screw allowed. No splayed main caps. Conventional flat tappet cam and lifters only, cannot alter lifter bores. OEM firing order cannot be changed (GM 1-8-4-3-6-5-7-2). May use oil restrictors. ‘Wet’ sump oiling system only. Steel oil pans only. Racing oil pans allowed. One inch inspection hole in all pans with no obstructions to crank and rods. Accumulator allowed.
   
   
2. CYLINDER HEADS: Steel only. Must be unaltered OEM and minimum 76 cc combustion chamber (GM). Only GM OEM approved head numbers are: 14079267, 3986336, 3986339, 3986339X, 3986388, 3932441, 376445, 3928454, 3932454, 3876487, 3973487, 3973487X, 3973493, 3951598, 468642, 330862, 333882, 3998920, 3998991, 3998993, 3998997, 3970126. Maximum size valves on these heads are 2.02 inch intake and 1.60 inch exhaust. May use Stock Replacement (SR) cylinder heads - Engine Quest (EQ) GM part number CH350I, (EQ) Chrysler part number CH318B, World Products Ford part number 53030 - 1.250 inch (+/- .015 tolerance) maximum O.D. valve springs. All SR heads must remain as produced, seat angles and valve sizes cannot be changed: three angle valve job only. (Absolutely no casting removal in valve pocket of EQ or World Product heads for any reason). Ford - no SVO heads; Chrysler no W-2 heads; 360 cubic inch heads only. No porting, polishing, or alterations allowed to any cylinder head or intake. Guide plates, screw-in shoulder studs (GM 0.375 inch max) and polylocks allowed. No stud girdles. Steel roller tip rocker arms allowed. GM - 1.250 inch (+/- .015 tolerance) maximum O.D. valve springs. No beehive valve springs allowed.
   
   
3. INTAKE: Unaltered OEM cast iron low rise, two or four barrel. Only unaltered ( no polishing or porting) aftermarket aluminum intakes allowed are: Weiand GM #7547, #7547-1: Ford #7515, #8023, or #7516; Chrysler #8022; Edelbrock GM #2701; Ford #7121, #7181, #7183; Chrysler # 2176. Cooling lines allowed on aluminum intakes. Unaltered OEM type harmonic balancer only. OEM type steel or aluminum water pumps only.
   
24. TRANSPONDERS
    Transponder must be mounted on the bottom right rear of motor plate.
    
25. OTHER
    Driver must be at least 14 years old.