Hobby Stock Rules
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- Rules apply at all times car is on track. Snell-rated SA2000, SA2005, or SA2010 helmet required. Roll bar padding required in driver compartment (Fire retardant recommended). 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 restraint system with no neck collar. Recommended: Fire retardant head sock and underwear.
- 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 (Y-type shoulder harness not allowed), must be mounted securely to roll cage, and must be no more than three years old. Kill switch required within easy reach of driver and must be clearly marked “OFF” and “ON”.
- It is recommended that each racecar have built-in fire extinguishing equipment, but cannot be of the dry powder type (must be Halon 1211 or equivalent).
- Drivers should have in their pit area as part of their equipment, at all times, a fully charged dry chemical, Halon (or its equivalent) fire extinguisher. Ten (10) or thirteen (13) pound fire extinguishers are highly recommended.
- Absolutely no plastic except from edge of firewall to body skin and inner wheel tub to body skin or nose and tail pieces.
- Any American OEM full body rear wheel drive passenger car 1964 or newer.
- Minimum wheelbase of (107”) required for all cars. Maximum 2” difference side to side permitted.
- Full frame cars must retain front frame horns. Rear of frame behind rear tires, no further forward than one inch behind factory seam, may be replaced in OEM location with 2” x 3” inch steel tubing with minimum 0.095” inch wall thickness, same length as material removed. Factory seam must remain visible.
- All unibody cars must have front frame and rear frame tied together. Frames may be X braced. No station wagon, front wheel drive, or 4 wheel drives allowed. All frame crossmembers must be unaltered in stock location (exception: transmission crossmember may be altered or removed and horn may be removed from center of front crossmember). Must have a 360 degree driveshaft loop no more than 6” behind the front u-joint. Must be minimum 0.250” x 2 “ steel or 1” tubing.
- Rear bumpers must be OEM in OEM location and capped at ends to body with steel, welded or bolted. Front bumpers must be mounted minimum (6) inches from front frame horns. Front bumper options: 1 of 2 – Front bumper OE must be complete and capped to body with steel, bolted or welded. 2 of 2 – Fabricated front bumper with rounded corners must be OE height with minimum 1.5” O.D. (maximum 2” O.D.) with minimum .083” (maximum 0.125”) wall thickness and must be covered with plastic nosepiece.
- Motor must be in stock location (fuel pump must be in front of unaltered crossmember).
- Main cage must consist of continuous hoops, minimum 1.666” O.D. (1.750” recommended) with a minimum 0.095” wall thickness (low carbon or mild steel recommended). Four post main cage required and must be properly welded to frame, NOT floor pan. Poor or missing welds may be deemed unsafe by a track official and may result in disqualification.
- A minimum 1 crossbar (minimum 1.666” O.D.) required in top halo and must be welded diagonally. Rear halo must be X braced. Front and rear down bars must be tied side to side. Top door bar must be a minimum of 36 inches inside to inside of front and rear down bars. Must be a minimum of 26 inches at bottom of top halo measured inside to inside of front and rear down bars. Must be a minimum height of 16 inches from top of door bar to bottom of halo. With helmet on and driver securely strapped in, driver’s head must not protrude above bottom of roll cage. All bars within reach must be padded with a material accepted by track officials, flame retardant recommended.
- Minimum of (4) 1.666” O.D. or (3) 1.750” O.D. horizontal door bars required on both driver and passenger sides (minimum 0.095” wall thickness). Horizontal door bars must be mounted perpendicular to frame and must have a minimum of (4) uprights from the frame to top door bar.
- Steel door plates made of 18 gage or 0.049” minimum thickness must be securely welded to outside of driver door bars. Plate must cover from top door bar to rocker and must extend from rear down bar to 5 inches in front of front edge of seat. Plate must be visible for inspection.
- Rear kickers (down bars) and fuel cell protection required (minimum 0.083” wall thickness), front hoops are allowed. If front hoop is not used must have two front kickers (down bars) welded to frame no further back than front of upper a-arm. Fuel cell protection and front kickers or hoop must be a minimum 0.083” wall thickness and 1.250” O.D. A maximum of (2) additional bars may be added for radiator protection not counting bar tying frame horns together and must be within confines of the body. Fuel cell protection must be same height as fuel cell and extend from frame rail to frame rail (maximum 1.750 O.D. tubing allowed) and must remain inside confines of the body.
- All vehicles MUST have tow loop or strap mounted front and rear and must be easily accessible.
- 1964 or newer American OEM stock passenger car bodies allowed. All bodies must be unaltered (no chop tops, short bodies, etc.) and remain stock appearing. All glass, plastic, upholstery, rear seats, lights, mirrors and chrome must be removed. Interior tin or other covers not allowed. All exterior body panels must be sheet metal, no aluminum. Only door panels may be fabricated and must resemble stock appearing door. Doors must be welded or bolted secure. All sunroof and T-top openings must be covered with sheet metal.
- Floor pan and fire wall must remain stock from front fire wall to rear fire wall. Stock body mounts must be visible and minimum 0.375” bolt must be able to pass through body and into body mount. No cutting of floor pan except for roll cage. All large holes in floor pan must be covered with sheet metal equal to or thicker than stock material. All holes in fire wall must be covered with minimum 0.049” sheet metal or aluminum. Rear firewall must be covered with 0.049” aluminum or steel and must seal driver compartment from trunk area. Rear firewall must be mounted in stock location.
- Hoods must remain stock dimensions, no custom fabricated hoods allowed. No hood scoops, spoilers, wings, or ground effects allowed. Air cleaner must not protrude through hood. Hood must be secured by a minimum of four hood pins located at all four corners. No tilt front ends, hood must be separate from fenders. Back of hood must be sealed from cockpit.
- Nosepiece and tailpiece must be securely riveted or bolted in place. No late model nosepieces.
- Trunk lids must be complete, no shortening allowed. Lids may be gutted. Lids must be secured at all four corners either by combination hinge/pin or pins at all four corners. May use aftermarket rear body covers. Material between rear fenders may be removed.
- No overlapping or shortening of body panels. Rear wheel drive 108” wheelbase bodies may be used on 112” wheelbase frames. OEM firewall for frame must be in same location as stock firewall for body used. Body may be trimmed for wheel/tire clearance only. Front and rear fender wells may be removed.
- Only rear opera windows may be covered.
a. All racecars must have numbers that contrast to body color and must be minimum 4” thick and 18” tall for both sides and must be 4” thick and 20” tall for roof and must be clearly legible. All racecars must have numbers on the right rear corner of the vehicle and must be minimum 4” tall.
b. Officials reserve the right to approve or disapprove any image of lettering or sponsorship on any racecar or pit vehicle entering race surface. Keep in mind this is intended to be a family fun facility.
- Maximum 7” visor allowed on front windshield area. This includes additional tape.
- Maximum 1” wide by 2” tall steel or lexan rub rails allowed – bolted flush to body. Steel must be capped.
- Driver compartment must be sealed off from engine, fuel cell, and ground.
- No loose objects or weights/ballast allowed in driver compartment. No rear view mirrors.
- Minimum 3 windshield bars required in front of driver and must be secured. Dash must be level with hood except for cowl in front of driver.
- Interior must be open, no decking allowed.
- All fuel lines passing through driver compartment must be protected by metal or galvanized pipe or conduit.
- Factory-manufactured high back racing seats are mandatory, and must be acceptable to officials. Homemade aluminum, plastic or fiberglass seats are not allowed. Full containment seats are recommended. Driver seat may be no further back than rear edge of B-pillar on metric chassis. All others must be no further back than rear edge of front door. Seat must be bolted in using minimum 0.375” grade 8 bolts and must be secured to frame or roll cage, NOT floor pan. Seat must be mounted in left front quadrant of driver compartment.
- One 12 volt passenger car battery only, must be securely mounted between and above frame rails, and battery must be covered with rubber or nonconductive plastic. Battery must not be mounted in driver compartment.
- Starter must bolt in OEM location. Aftermarket starters allowed. 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.
- GM must utilize OEM GM distributor. Chrysler and Ford may use aftermarket HEI (bushing type only). Roller bearings are not allowed. Distributors must utilize stock-type components. Circuit board modules are not allowed. No ignition boxes. Mechanical and vacuum advance may be locked.
- No unapproved cameras, transmitting or listening devices (exception is one-way RACEceiver radio by officials), timing retard controls, or digital gauges (including tach). No electronic monitoring computer devices capable of storing or transmitting information except memory recall analog tach.
- All wiring must be visible for inspection. OEM type alternator with internal regulator allowed. No electronic traction control devices.
- Kill switch required within easy reach of the driver. The switch must be clearly marked “OFF” and “ON”. All battery cables and electrical must be securely mounted and protected.
- Automotive gasoline or racing fuel allowed ONLY! NO E85! No alcohol!
- Electric fuel pumps are not allowed. No piston style pumps allowed; diaphragm style only.
- A limit of one (1) standard fuel filter is allowed between the fuel cell and the carburetor. Fuel filter cannot be mounted in the driver compartment.
- No cool cans, cold air boxes, or air cleaner ductwork.
a) Option 1 – 2 bbl. OEM Carburetor: GM to GM, Ford to Ford, Chrysler to Chrysler; must use unaltered OEM two barrel carburetor for that engine, except: booster I.D. may be machined to 0.250”, venturi I.D. machined to 1.375” and throttle bore I.D machined to 1.6875” on Rochester carburetor. 0.625” minimum booster height on Rochester carburetor. Choke plate must be removed. Car must weigh a minimum 3000 lbs. with this combination.
b) Option 2 – May use unaltered Holley part no. 0-80787-1- with no modifications, or part no. 0-7448 which may be modified to meet the specs of part no. 0-80787-1. Unaltered 500 c.f.m. Holley – part no. 0-4412 may also be used. Holley carburetor components only may be used. Car must weigh a minimum of 3450 lbs. with this combination.
- Fuel cell must be commercially manufactured for racing applications. No boat or stock automotive fuel tanks. Tanks must be securely fastened inside trunk of racecar, above the level of stock trunk floor. Fuel cells must be in steel container. All mounts must be made of steel and surround the fuel cell and attached to frame or roll cage. No adjustable fuel cell mounts.
- Must have check valve. Fuel cell vent, including cap vent, must have check valves, a flapper spring or ball-type filler valve.
- Carburetors may be claimed for $175.00 fee. See claim rules (section 21).
- Steel, unaltered OEM, or unaltered OEM replacement, four wheel disc or disc (front) and drum (rear) brakes. Aluminum GM drums are not allowed. No two piece rotors.
- A single OEM or OEM replacement master cylinder only, must be mounted in stock location. Pushrods my be fabricated for removal of brake booster. Pedals may be aftermarket or OEM.
- All calipers must be OEM steel.
- All four wheels must have functional brakes. Brakes will be tested!
- Brake pads must contain complete friction surface, sectioning of pads prohibited.
- All components must be steel unaltered OEM, in OEM location and match frame. OEM steering column may be replaced with steel steering shafts (steering shafts must have a joint every 5 ft., collapsible steering shafts highly recommended). Steel knuckles only.
- No quicksteer of any type allowed. Quick release steering wheel coupler mandatory, may be ring or pin design. Steel or aluminum coupler allowed.
- All components and mounts must be steel, unaltered OEM, in OEM location and match frame. Magnet must stick to all components.
- OEM or OEM replacement type rubber A-frame bushings only. OEM type ball joints only. No sway bars, spring spacers, chains or cables. Exceptions are: for 1978-1987 GM mid-sized metric frame, OEM upper A-frame may be replaced using aftermarket upper A-frame (steel or aluminum cross shaft allowed. Bolt on spindle savers allowed). Upper A-frame mount must remain OEM and cannot be moved.
- Coil springs must be minimum 4.5” O.D. and non-progressive.
- No spring spacers, sway bars, chains, or cables allowed. No jack bolts or spring buckets allowed. Springs may be cut or heated.
- All components and mounts must be steel, unaltered, OEM, in OEM location and match frame.
- OEM replacement rubber control arm bushings only. Center of rear lower control arm bolt holes may be no lower than three 3” from bottom of axle housing and the same on both left and right. Trailing arm bolts must remain tight.
- Control arms must be level side to side and non-adjustable. Control arms may be fabricated of steel 2” x 2” tubing and must remain stock dimensions. No adjustable arms or swedge tubes allowed. No drilling or sectioning of bushings allowed.
- No independent rear suspension. No sway bars, panhard bars, spring spacers, extensions, chains or cables. No spring buckets or jack bolts.
Shocks and Springs
- One unaltered steel, nonadjustable, stock mount shock, in OEM location, per wheel. No coil-over shocks, air shocks, remote reservoir shocks. No Schrader or bladder type valve allowed. No coil-over eliminators.
- Coil springs must be minimum 4.5” O.D. and non-progressive.
- OEM and Ford 9” rear-ends and floater rear-ends are permitted, but must be mounted like stock rear-end for that make and model. Truck rear-ends and quick changes are not allowed.
- Rear-end may be welded or a mini spool may be used, full spools are not allowed. No torque dividing differentials.
- Rear-end must be centered on chassis.
- Lightened gears are not allowed. One inch inspection hole in housing required.
- Gun-drilled or titanium axles are not allowed (axles must be made of steel).
- All mounts must be securely welded, no floating or clamped mounts.
Tires and Wheels
- 8” or 10” inch wide steel wheels only. NASCAR pull-off slicks. Tires must be used pull-offs, no new tires. Must have minimum 0.375” studs with 1” lug nuts. Tires must durometer 60 or more after the A feature. May run bead locks on right rear only. Tires may be grooved, NO siping allowed. (Used G60 or KK704 USED tires allowed and recommended, may be grooved or siped. Again USED G60s ONLY!!!!)
- Softening is not allowed. Solvents of any kind are not allowed. Altering tires with any components or chemicals which alter the manufacturer’s baseline-settings of the tire is not allowed.
- Minimum “diameter, white, steel drive shaft only. Steel slip-yokes and differential yokes only.
- 360-degree drive shaft loop required, constructed of at least 0.125” by 2” steel or 1”tubing, and mounted 6-inches back from front U-joint.
- Automatic transmission
a) Must be OE automatic with torque converter. All OE forward and reverse gears must be operational.
b) Torque converter must be a minimum 10” and must have a minimum 0.125” inch plug, and contain three (3) quarts of transmission fluid. Must be able to hold brake while is running and car will not die.
c) Must have approved scatter shield constructed of minimum 0.125” by 3” steel, 270 degrees around flexplate. Flexplate must be full, unaltered OEM, or OEM replacement. No manual bump starts allowed.
- Standard transmission
a) 3 or 4 speed transmissions. All OEM forward and reverse gears must be operational.
b) Flywheels must be stock OEM and weigh a minimum of sixteen 16 lbs. Clutch must be a minimum 10.5” outside diameter. Lightened flywheels are not allowed. Aluminum flywheels are not allowed.
c) Must have approved scatter shield constructed of minimum 0.125” by 3” steel, 270 degrees around flywheel.
- Maximum of 368 cubic inches (370 C.I. for Chrysler) is permitted. Note: Cubic inches will be checked. Maximum 3.484” stroke for GM, maximum 3.500” stroke for Ford or Mopar.
- Maximum 175 lbs. compression ratio.
- OEM steel passenger vehicle production block only. No GM Bowtie, Ford SVO or Chrysler W components allowed. GM approved block numbers are: 3892657, 3914660, 3914678, 3932388, 3932386, 3956618, 3970000, 3970006, 3970010, 3970014, 10066033, 10066036, 10243880, 14010207, 14010209, 14010287, 14016376, 14016379, 10054727, 14088528, 14088548, 14088552, 14093638, and 14101148. Stroke must match block. No 400 or larger cubic inch parts allowed. Steel only. Absolutely no machining allowed on the exterior of the block.
- Flat top or dish pistons only, no gas ported pistons. OEM or OEM replacement steel crankshaft only – cannot be lightened, no 4340 cranks. GM 5.7 or 6-inch stock appearing rod allowed only. All others must have stock rod configurations with stock appearing rods. Cap screws allowed. Aftermarket rod bolts allowed.
- Must be unaltered approved OEM and minimum 76 cc combustion chamber. 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” intake and 1.60” exhaust. Valve springs must be stock diameter(1.250”) no beehive springs allowed. Maximum 125 lb. seat spring pressure allowed. Screw-in studs, guide plates and poly-locks are permitted. Stud girdles are not allowed. May use Engine Quest (EQ) Stock Replacement (SR) cylinder head, part number CH350I, head 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 head, for any reason); Ford – no aftermarket or SVO heads; Chrysler – no after market or W-2 heads, 360 cubic inch heads only. 2.04” intake and 1.70” exhaust valves max for Ford and Chrysler. Bowl hog 80 degree maximum and may not be any deeper than 1.50” into pocket measured from chamber floor, not valve seat. Porting, polishing or alterations of any kind to heads, block, or intake is strictly forbidden.
- Conventional flat tappet cam/lifters only, cannot alter lifter bores. OEM firing order cannot be changed (GM: 1-8-4-3-6-5-7-2).
- Aftermarket performance harmonic balancers are not allowed. Stock replacement balancers only.
- Holley 2bbl and Rochester 2bbl - Intake must be cast iron no high rise (NO BOW TIES). Intake cannot be altered or cut in any way except at top of intake to allow for 2 bbl. adapters. Center divider may be cut to 1” below surface. Absolutely NO port matching allowed. Rochester 2bbl only – may use aluminum Edelbrock #2701, 7121, 7181, 7183, or 2915 and Weiand # 7547-1, 7547, 7515, 8023, 7516, or 7545 (absolutely no modifications to aftermarket intakes). Absolutely NO port matching allowed.
- A minimum (1) 1” plug above the oil level in the side of the oil pan is recommended. If not utilizing a plug, oil pan will have to be removed at time of inspection.
- Only (1) minimum 2 core radiator allowed in stock location. Overflow tubes must be directed toward ground. Steel or aluminum V-belt pulleys only. No electric fans. Aluminum water pumps allowed.
- Stamped steel rocker arms or roller tip rocker arms only!
- Must be cast iron exhaust manifolds. Headers are not allowed. Exhaust must extend past the firewall. Must remain dual exhaust. Crossover or “Y” pipes are not allowed. May use manifold adapters or port manifolds to fit only! Must have mufflers (3-ring, cone, perforated insert, IMCA 609, or glass packs allowed)!
- The overall weight of the racecar shall be measured at the conclusion of an event with the driver in the cockpit, wearing complete racing apparel. You may not add missing or lost parts after race.
- Rochester 2bbl application- minimum 3000 lbs. Holley 2bbl applications – minimum 3450 lbs.
- Any driver that finishes on lead lap and have competed in the prior 2 weeks competition may protest another driver that finishes in front of him or her. All protests must be submitted in writing within 15 minutes after completion of race. Once the protest has been initiated the protest cannot be recalled. All protests must be made in cash only and must be given to the appointed track official. All protesting drivers may be accompanied by one additional person. Protested drivers are allowed two additional people to aid with removing of protested parts. Teams are allowed 1 hour for removing any components except in the case a rod and piston need be removed in which 1 hour 30 minutes will be allowed. All teams are responsible for having tools necessary for disassembly. If components cannot be removed within allotted time the protested driver will be disqualified.
a) Section protest – $250.00, $25.00 goes to track – Driver may protest suspension, engine, transmission, or fuel. If fuel is protested laboratory fees will be taken from protest fee. Protests may be anonymous, however, only protesting driver may be present.
b) Complete protest - $425.00, $50.00 goes to track – Complete vehicle may be inspected, only one head may be removed, protesting driver chooses which side. If fuel is protested laboratory fees will be taken from protest fee. Protests may be anonymous, however, only protesting driver may be present.
- If protested driver is found legal, protest monies will be issued to protested driver less fees.
- If protested driver is found illegal, protest monies will be returned to protesting driver less fees and penalties will apply to protested driver.
a) Violations – First offense, Loss of points and winnings for current night. Second offense loss of points year to date and suspension up to four weeks in which decision will be made by track director.
- Any driver may protest a total of 2 times per season. A driver may only be protested by another driver a total of 2 times per season.
- Southern Oklahoma Speedway has the right to protest any driver at any time in which a $50.00 teardown fee will be given to protested driver if found legal.
- All decisions will be made by Southern Oklahoma Speedway officials and all decisions are FINAL.
- Any top 4 finishing driver may have their carburetor claimed by another driver finishing on the lead lap behind them for a fee of $175.00 or swap. Claimed driver has decision for cash or swap. Claiming driver must have competed for the prior two weeks of competition at Southern Oklahoma Speedway without disqualification. Claim must be submitted before leaving the race surface to an SOS official. Claimed driver is responsible for removing own components and must not leave the tech area until claim is complete. Drivers may be claimed a total of 3 times per season. If claim is denied penalty will be loss of points year to date and loss of current night winnings and will not be able to claim the remainder of the season. Southern Oklahoma Speedway has the right to claim after the third claim has been met.
- Claiming drivers will not be eligible to claim again for a minimum of 2 weeks and achieving a top 4 finish in an “A” Feature main event.