1. SAFETY EQUIPMENT: Rules apply at all times car is on track. Snell-rated SA2005 or SA2010 helmet required. Roll bar padding required in driver compartment. Recommended: Fire retardant padding. SFI-approved full fire suit required. Fire retardant gloves, shoes and neck brace (or head and neck restraint) required. Right and left seat head supports required if using head and neck restraint system. Recommended: Fire retardant head sock and underwear, collapsible steering shaft. Driver-side window net required, minimum 16 inch by 20 inch ribbon or mesh style, and must be mounted to roll cage so latch is at top front of window. Minimum three inch (two inch with head restraint system) wide SFI-approved five point safety belt assembly required, must be mounted securely to main roll cage. Recommended: Safety belts no more than two years old. Kill switch required within easy reach of driver and must be clearly marked ‘OFF’ and ‘ON’.
2. FRAME: 1978-1987 OEM midsize GM metric full frame only. Minimum wheelbase 107 inches, maximum 109 inches, both sides. Frame must be full and complete, cannot be widened, narrowed, shortened, lengthened, or be cut, bent, or altered to change suspension brackets, except upper control arm brackets on front end. All frame bolt holes must remain in OEM location. Front frame horns may be removed in front of steering box. Front frame may be cut for radiator clearance. Frame may be notched for seat clearance. Transmission cross member mounts may be removed, no further forward than frame welds. Rear of frame, behind upper shock mounts, may be replaced with round, square, or rectangular tubing. No part of frame can be lower than five inches from ground except front cross member. No other frame alterations allowed.
3. ROLL CAGE: Must consist of continuous hoops, minimum 1.5 inch O.D. tubing, with a minimum wall thickness of .095 inch for main cage. Cages must be steel or chrome-moly. Main cage no further forward than rear of engine and no further back than front edge of rear tire. Four bars, two per side, may extend from main roll cage to main frame points in front of the upper control arms. These bars may have two additional braces per side to the main frame. Six bars may extend from the main cage to the rear. X-bracing is allowed. 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. All bars forward of cage must be lower than hood.
4. DOOR BARS: Minimum three driver side door bars required, minimum 1.5 inch O.D. and .083 inch wall thickness, must be parallel to ground and perpendicular to driver, and welded to front and rear of roll cage. Minimum two passenger side door bars required, must have at least one cross door bar, horizontal or angled. Steel door plate, 18 gauge or .049 inch, required.
5. BODY: (See diagram) No composite or plastic body panels allowed except roof rock guard and hood scoop. Body must be same width, front to rear, and parallel to OEM frame. Aluminum nose panel must be flat. Maximum 2.250 inch side fins allowed on aluminum nose. 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 and be no lower than two 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. No reverse hood rake allowed. No panel in front of right door to engine compartment. No inner panels. No complete car covers, rear tail cover allowed in personal pit area only. Must have front and rear roof support posts. Driver and passenger side windows must have at least 12 inch opening (height and width). Full size, fiberglass or aluminum roof only (see diagram). 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). Solid sail panels must resemble all aspects of drawing and may not extend ahead of back of seat. Rear spoiler (optional) may be minimum one inch or maximum eight inches in material height and maximum 67 inches wide. Spoiler may have stiffener, must be one inch or more down from top. Maximum three spoiler braces allowed, must be mounted in line. Spoiler braces must resemble all aspects of drawing. Spoiler must be mounted within confines of spoiler braces. No fins, lips or wings allowed. Maximum four inch plastic skirting allowed on bottom of doors and quarters. Car number must be minimum four inches thick and 20 inches tall and clearly visible, on both sides and roof of car; six inches tall on rear and front if possible.
6. 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 further back than steering wheel. Floor pan must be metal or aluminum and cover entire driver compartment. Aluminum high-back seat only, must be securely bolted, using minimum 0.375 inch bolts, to roll cage and support system. 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. No oil coolers allowed in driver compartment. No devices that would enable driver adjustment to alter wheelbase or for weight jacking while car is in competition. No mirrors of any kind.
7. FRONT SUSPENSION: All components and mounts must be steel, unaltered OEM, in OEM location, and match frame. No jack bolts allowed. Adjustable spring buckets are allowed. Must use OEM upper and lower A-frames and mounts. OEM upper A-frame may be replaced using aftermarket upper A-frame (steel or aluminum cross shaft allowed). Upper A-frame mounts may be modified and moved for caster and camber adjustment, but must remain OEM material. Lower A-frame mounts and bolt holes on frame must be in OEM location, mount may be notched for clearance. All A-frame bushings may be aftermarket, but no offset or bearing type. OEM or OEM replacement ball joints allowed, may be tacked in. Sway bars (optional) and brackets must remain OEM. No suspension stops of any kind allowed.
8. STEERING: All components must be steel, unaltered OEM, in OEM location and match frame. No grinding, lightening or welding on any steering parts. Spindle may be reamed and bolt on spindle savers are allowed. Steel steering shafts and knuckles only. Steering quickener (optional), steering wheel and quick release (required) may be aluminum. Power steering pump and reservoir must remain one unit. Driver compartment steering may be modified, must be kept on left side. No rack and pinion.
9. SHOCKS: One unaltered steel, nonadjustable, OEM mount shock, in OEM location, (except 3 link rear suspension, shocks may be remounted). All shocks must completely collapse at any time. No external or internal bumpers or stops. Mounting spacers and weld or screw-on shock ends allowed. No coil-over shocks, air shocks, remote reservoir shocks, or shock covers. No Schrader or bladder type valve allowed.
10. SPRINGS: One steel spring (racing allowed) per wheel only. Minimum 4.5 inches O.D., non-progressive coils only. No torsion bars or air bags.
11.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. Rear shocks cannot be mounted on control arms. All rear control arms and panhard bars must be straight. Must utilize one of the following designs:
(A) Aftermarket three link design requirements: Must use 16 inch minimum, 24 inch maximum lower control arms. Must use one upper control arm, solid tube only, located at top center of rear end housing and remain centered (one inch tolerance) on housing over drive shaft. 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 the axle tube. Must use steel upper weight jack. No floating or bearing rear spring perches/cups allowed, top or bottom. No suspension stops of any kind allowed.
(B) 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.
(C) 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 rear-end housing. Must use steel upper weight jack.
CARS THAT WERE RACED AT OSP IN 2013 WILL BE ALLOWED TO COMPETE IN 2014 AS RACED IN 2013. CARS THAT DID NOT RACE IN 2013 MUST MEET ABOVE RULES. ( REAR SUSPENSION ONLY) All MUST COMPLY IN 2015.
OKLAHOMA SPORTS PARK IN 2013, THE REAR SUSPENSION YOU RAN LAST YEAR WILL BE LEGAL FOR 2014, BUT IN 2015 YOU WILL NEED TO ADHERE TO THE 2014 RULES.
12. REAR END: Must use OEM 7.5 inch GM 10 bolt rear end (bracing optional), must remain stock width. Ford or floater rear end allowed. Housing end, from control arm mount out, may be modified with three inch tubing to accept nine inch Ford axle. If Ford axles are used, rear-end must remain minimum GM width or maximum three inches wider. Steel components only. OEM mounts on lower control arms must remain in OEM location on original 7.5 inch tube housing. Aftermarket axles, mini-spools and C-clip eliminators allowed. Locked rear ends only, no torque dividing differentials allowed. No full or aluminum spools allowed. Any gear ratio allowed but housing must remain unaltered. No quick change devices.
13. BUMPERS/RUB RAILS: (see diagram) Steel bumpers must be on front and rear at all times and welded, or mounted with minimum 0.375 inch bolts. Two bar front bumper must be minimum 1.25 inch O.D. tubing with minimum .065 inch wall thickness (maximum 0.095 inch) mounted frame end to frame end. Rear bumper must be constructed of minimum 1.25 inch tubing, 0.095 wall thickness. Maximum 1.50 inch O.D. tubing, .095 inch wall thickness fuel cell protection bar required, must cover rear and extend past both sides of cell, may be welded to rear bumper. Rear bumper may be maximum six inches beyond rear deck. All bumpers and rub rails must be capped with no sharp edges. Single bar rub rail from front to rear wheel allowed on each side, no center supports allowed, maximum 1.50 inch O.D. tubing and .095 inch wall thickness, must be mounted to cage at front and rear of rub rail.
14. TIRES/WHEELS: May use unaltered Hoosier ‘500’ Race tire, with IMCA stamped or unstamped on sidewall. 27 x 8 x 15 or 26.5 x 8 x 15 ‘stagger tire’ allowed. No chemical softening, conditioning or grooving of tires. Tires may be ground or siped within confines of tread. Any offset allowed. May use bead lock. External steel bead lock only and it cannot make wheel any narrower than eight inches and no wider than 8.75-inches. Steel bolts only. Foam type or plastic outer mud cover allowed on right side wheels. Inner mud cover allowed on left rear only. No bleeder valves. Must use minimum one inch O.D. steel lug nuts and 0.625 inch studs are recommended. No wheel spacers allowed with OEM studs. Wheel adapters are treated as spacers and may be aluminum, maximum 1.50 inches thick.
15. BRAKES: Must be steel OEM, operative four wheel, drum or disc. Right front brake shut-off allowed. 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. Single or dual aftermarket master cylinders allowed. Driver adjustable dual pedal brake bias allowed. Additional proportioning valve (in-line type) allowed, must be out of driver reach. Rear rotors may be aftermarket, minimum 0.81 inch thickness (new), maximum 12 inch O.D. Vented solid surface rotors only, no scalloped or ceramic coated rotors. Rear caliper brackets must be welded to housing.
16. EXHAUST: Mufflers required. Must meet noise levels outlined in General rules.
17. FUEL CELL: Recommended: 12 gallon), must be in minimum 20 gauge steel container. Must mount with minimum two solid steel straps around entire cell, two inches wide and 0.125 inch thick, between frame rails and behind rear axle. 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. No part of cell can be lower than protective tubing. No regulators, bypass fuel systems, pressurized, or return lines allowed. One fuel filter allowed. No cool cans. Any air cleaner allowed. No cold air boxes or ducting of any kind between engine and hood. Mechanical OEM type push rod fuel pumps only. Maximum 0.100 inch thick carburetor gaskets on all engines. STANDARDENGINE: must use IMCA approved naturally aspirated, unaltered 500 c.f.m. Holley – part # 0-4412, may be modified to Holley HP Dorton part no. 0-80583-1 specs only. Float bowl must face forward. Any adapter, maximum one inch thick. No throttle bore adjustable carburetor spacers. GM CRATE ENGINE: may use any Holley four-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.
18. FUEL: Gasoline only. Racing fuel allowed. No performance enhancing additives or scented additives. Fuel must pass both dielectric meter and chemical tests. Fuel sample may be taken from any car at any time.
19. WEIGHT: Minimum weight limit of 2,350 pounds after race with driver in car. Weights must not be used in driver compartment or outside body. All weights must be securely mounted with at least two 0.5 inch bolts, painted white with car number on it. No titanium, magnesium, stainless steel or carbon fiber components. Solid steel fasteners only.
20. BATTERY/STARTER: One 12 volt battery only, must be securely mounted and positive terminal must be covered. Aftermarket starter allowed, must bolt in OEM location and directly engage flex plate/flywheel. Car must have capability of starting without being pushed or pulled. Car must leave initial staging area on demand, unaided, or go to rear of that race.
21. GAUGES/ELECTRONICS: No unapproved cameras, transmitting or listening devices (exception is one-way Race Receiver radio by officials), timing retard controls, or digital gauges (including tack). No electronic monitoring computer devices capable of storing or transmitting information except memory recall analog tack. 12 volt ignition system and OEM HEI style ignitions only. Ford/Chrysler may use HEI distributor. No crank triggers. Any module that fits inside distributor with no alteration allowed. Crate engine MUST use original HEI distributor with MSD #8728 rev-control and 6,200 rpm chip. Standard engine MAY use MSD #8728 rev-control with any rpm chip. No unapproved or additional ignition accessories allowed. 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. Only gauges allowed are analog oil pressure, fuel pressure, brake bias, water temperature and tack. OEM type alternator with internal regulator allowed. No electronic traction control devices.
22. TRANSMISSION/DRIVE SHAFT: Only OEM production transmissions allowed. No aftermarket transmissions allowed. No ‘in and out’ boxes or quick change devices allowed. With engine running and car in a still position, must be able to engage car in gear and move forward, then backward. Functioning shift levers must be in OEM location. Transmission fluid coolers allowed. Flywheel, flex plate and converter must be steel.
Automatic: Any OEM automatic transmission allowed. Must use functioning, minimum 10 inch diameter steel torque converter. No direct drives, couplers, valved pumps, or bleeder style valve bodies. Must have at least one forward gear and reverse gear, gears must function. Must have an approved scatter shield constructed of .125 inch by three-inch steel, 270 degrees around top of flex plate. GM automatic must be used with GM engine, may be used with Ford or Chrysler engine. Stall converters allowed. Steel OEM style flex plate only, must be bolted directly to end of crankshaft. No bump starts allowed.
Manual: Three, four or five speed OEM manual transmissions only. All gears must function. Must have functioning 10.5 inch minimum diameter clutch and pressure plate bolted directly to steel flywheel. These components must rotate, consistent with engine rpm, while car is in any gear. Must use explosion-proof steel bell housing 180 degrees around top of clutch and flywheel. No mini-clutches or couplers. Minimum 9-inch diameter Ford clutch allowed. Hydraulic slave cylinder/throw out bearing allowed.
Drive Shaft: Steel slip-yokes only. Minimum two inch diameter, white, steel drive shaft only. 360-degree drive shaft loop required, constructed of at least 0.125 inch by two inch steel, or one inch tubing, mounted six inches back from front U-joint.
23. ENGINE COMPARTMENT: Rear of engine (bell housing flange) must be mounted at least 70 inches forward from centerline of rear axle. Minimum 11 inch engine height from ground to center of crankshaft. One radiator allowed, steel or aluminum, 27 inches by 19 inches maximum in size, must be mounted in front of engine. Racing cap and electric fans allowed. No sprinklers. Power steering pump and reservoir must remain one unit and mount in front of engine. Side engine mounts only (OEM or 45-degree style) must be steel, aluminum mid-plate allowed. No vacuum pumps, oil coolers or remote oil filters.
24. ENGINE OPTIONS AND SPECIFICATIONS: All cars utilizing a GM602 crate engine must clearly display on both front roof posts the word CRATE. Must be contrasting in color from body, minimum two inches tall. Markers not acceptable.
(A) CRATE ENGINE: Must use unaltered sealed GM #88958602 or #19258602 crate engine. Effective January 1, 2016, all GM 602 Crate engines must have IMCA Cable-Lok seals. Upon inspection, any different, altered or missing GM seal bolts will result in disqualification.
(B) STANDARD ENGINE: All engines must be able to be used in conventional passenger car without alterations. External engine casting and threaded holes cannot be altered.
BLOCK: OEM steel passenger vehicle production block only. No GM bowtie, Ford SVO or Chrysler W-2 components allowed. GM approved blocks are: 10105123, 10066034, 283, 302, 305, 307, 327, 350. Ford: 260, 289, 302, 351. Chrysler: 273, 318, 340, 360, no hemis. Maximum cubic inch limits: GM 364, Ford 363, Chrysler 370, no tolerance. Violation of cubic inch limit must be verified by removal of head and will result in disqualification. No 400 or larger cubic inch parts allowed. Any flat top or dished pistons allowed, no gas ported pistons. Stroke must match block. Maximum 175 lbs. per cylinder compression, no tolerance. Compression checked with one spark plug removed, turned five engine compression revolutions. Engines may be balanced and block decked. Oil filter system must remain OEM. ‘Wet’ sump oiling system only. OEM or OEM appearing replacement steel crankshaft only - cannot be lightened. No aero wing, bullnose, knife edge, undercut or drilling of second or third rod throws allowed. OEM or OEM appearing replacement steel rods only - GM must use maximum 5.7-inch rod or GM Vortec rod part number 10108688. No cap screws. No splayed main caps. Racing oil pans allowed. Mandatory one inch inspection hole in all pans - no obstructions to crank and rods. Engine bolts may be aftermarket. Fluid dampener balancer allowed. No roller bearings allowed.
CYLINDER HEADS: Steel only. GM OEM approved head numbers are (last 3 digits): 126, 185, 336, 441, 445, 487, 487X, 493, 598, 624, 862, 882, 920, 993, 997, with valve no larger than 2.02 inch intake and 1.60 inch exhaust. May use Stock Replacement (SR) cylinder heads: Engine Quest (EQ) GM pat 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 Products head, for any reason). No porting, polishing or unapproved alterations allowed to any cylinder head or intake, disqualification and $250 fine if illegal. Any cast iron OEM Ford and Chrysler heads allowed with valves no larger than 2.04 inch intake and 1.70 inch exhaust. Headers must bolt directly to heads with correct numbers. No vortec, bowtie, SVO, or W-2 heads allowed. Flat milling allowed. Guide plates, screw-in shouldered studs (0.375 inch max) and polylocks allowed. No stud girdles. Roller rockers allowed. Chrysler may use OEM rocker arm bars. Any length push rods allowed. OEM diameter springs (GM - 1.250 inch maximum O.D.) must match heads, no beehive valve springs allowed.
INTAKE: Unaltered, approved OEM cast iron low rise, two- or four-barrel. Only unaltered (no porting or polishing) aftermarket aluminum intakes allowed are: Weiand GM #7547, #7547-1; Ford #7515, #8023 or #7516; Chrysler #7545, #8022; Edelbrock GM #2701; Ford #7121, #7181, #7183; Chrysler #2915. Cooling lines allowed on aluminum intakes. Ford may use OEM aluminum intake, no under air or hi-rise. Belt driven, OEM style water pumps only, no aluminum water pumps on GM engine.
CAMSHAFT: Conventional flat tappet cam and lifters allowed, cannot alter lifter bores. OEM firing order cannot be changed (GM: 1-8-4-3-6-5-7-2). No maximum cam lift. No vacuum rule. Must be chain driven, no gear/belt drives.