2020 Hobby Stock Rules

All Rule Changes are in RED


1. 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.
2. Right and left seat head supports required if using head restraint system with no neck collar. Recommended: Fire retardant head sock and underwear.
3. 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.
4. 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”.
5. 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).
6. 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.
7. Absolutely no plastic except from edge of firewall to body skin and inner wheel tub to body skin or nose and tail pieces.


1. Any American OEM full body rear wheel drive passenger car 1964 or newer.
2. Minimum wheelbase of (107”) required for all cars.  Maximum 2” difference side to side permitted.
3. 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.
4. 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.
5. 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.
6. Motor must be in stock location (fuel pump must be in front of unaltered crossmember).

Roll Cage

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. All vehicles MUST have tow loop or strap mounted front and rear and must be easily accessible.


1. 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.
Fiberglass roof part # Shell Valley F1015-81-88MCRW will be allowed.

2 After market floor pan 
and fire wall can be utilize, must be at least 18 gauge. B&C Piller must remain OEM dimensions.  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.
3. 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.
4. Nosepiece and tailpiece must be securely riveted or bolted in place. No late model nosepieces.
5. 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.
6. 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.
7. Only rear opera windows may be covered.
8. Appearance:

       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.

9. Maximum 7” visor allowed on front windshield area. This includes additional tape.
10. Maximum 1” wide by 2” tall steel or lexan rub rails allowed – bolted flush to body.  Steel must be capped.

Driver Compartment

1. Driver compartment must be sealed off from engine, fuel cell, and ground.
2. No loose objects or weights/ballast allowed in driver compartment. No rear view mirrors.
3. 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.
4. Interior must be open, no decking allowed.
5. All fuel lines passing through driver compartment must be protected by metal or galvanized pipe or conduit.
6. 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.


1. 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.
2. 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.
3. 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.
4. 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.
5. All wiring must be visible for inspection. OEM type alternator with internal regulator allowed. No electronic traction control devices.
6. 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.

Fuel System

1. Automotive gasoline or racing fuel allowed ONLY!  NO E85!  No alcohol!
2. Electric fuel pumps are not allowed.  No piston style pumps allowed; diaphragm style only.
3. 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.
4. No cool cans, cold air boxes, or air cleaner ductwork.

5. Carburetor:
    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.
 6. 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.
7. Must have check valve. Fuel cell vent, including cap vent, must have check valves, a flapper spring or ball-type filler valve.
8. Carburetors may be claimed for
$250.00 fee. See claim rules (section 21).


1. 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.
2. 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.
3. All calipers must be OEM steel.
4. All four wheels must have functional brakes. Brakes will be tested!
5. Brake pads must contain complete friction surface, sectioning of pads prohibited.


1. 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 5ft., collapsible steering shafts highly recommended). Steel knuckles only.
2. Quick release steering wheel coupler mandatory, may be ring or pin design.  Steel or aluminum coupler allowed.

Front Suspension

1. All components and mounts must be steel, unaltered OEM, in OEM location and match frame. Magnet must stick to all components.
2. 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 minimum of 8 or maximum of 8 1/2 control arm  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.
3. Coil springs must be minimum 4.5” O.D. and non-progressive.
4. No spring spacers, sway bars, chains, or cables allowed. No jack bolts or spring buckets allowed. Springs may be cut or heated.

Rear Suspension

1. All components and mounts must be steel, unaltered, OEM, in OEM location and match frame.
2. 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.
3. 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.
4. No independent rear suspension. No sway bars, panhard bars, spring spacers, extensions, chains or cables.  No spring buckets or jack bolts. 

Shocks and Springs

1. 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.
2. Coil springs must be minimum 4.5” O.D. and a
maximum length of 15” and non-progressive. 

Rear End

1. OEM and Ford 9” rear-ends and floater rear-ends are permitted, but must be
in stock location for that make and model. Truck rear-ends and quick changes are not allowed.
2. Rear-end may be welded or a mini spool may be used, full spools are not allowed. No torque dividing differentials.
2. Rear-end must be centered on chassis.
3. Lightened gears are not allowed. One inch inspection hole in housing required.
4. Gun-drilled or titanium axles are not allowed (axles must be made of steel).
5. All mounts must be securely welded,
and in stock location with trailing arm bolt hole must be 2.25-2.50 from bottom of housing, no floating or clamped mounts.

Tires and Wheels

1. May be a maximum of eight (8) inches wide, fifteen (15) inches diameter and made of steel.

2. One (1) inch steel lug nuts are mandatory on all wheels.

3. Bead locks and/or screws are not allowed.

4. Mud plug and wheel cover permitted on right rear only. Wheel cover must be made of plastic and be bolted. Dzus fasteners are not allowed. The ring that holds the wheel cover must be welded to the wheel in at least three places.

5. Bleeder valves are not allowed.


1. Minimum “diameter, white, steel drive shaft only. Steel slip-yokes and differential yokes only.
2. 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 brakes
           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

3 speed OEM no aluminum case allowed. 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” outside
and weight a minimum of 15.5 lbs. 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



Must use unaltered sealed GM #88958602 or #19258602 crate engine. Must also run IMCA approve Rodchester 2 barrel carburetor and 6200 chip. Effective January 1, 2019, all GM 602 Crate engines must have IMCA Cable-Lock seals.  Upon inspection, any different, altered or missing GM seal bolts and not using required spacer, pushrods, valve springs or rocker arms will result in disqualification and 30-day suspension.

1. 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.
2. Maximum 175 lbs. compression ratio.
3. 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. 
4. 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.
5. 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 1.94” intake and 1.50” 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.   
 On all heads seat angle and valve angel must remain as manufactured. Porting, polishing , angle milling or alterations of any kind to heads,  block, or intake is strictly forbidden.
6. 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).
7. Aftermarket performance harmonic balancers are not allowed. Stock replacement balancers only.
8. 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.
9. 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.
10. 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.
11. Stamped steel rocker arms or roller tip rocker arms only!


 Stock unaltered cast iron exhaust manifolds only no porting or grinding allowed. No Chevy center dump, Corvette, marine, Lt1 or tubular steel type manifolds. No adaptors between head and manifold must be able to use all OEM exhaust bolt holes in head. No two into one exhaust or x pipes must remain duals. Must have mufflers. (3 ring, cone, perforated insert, IMCA 609)


WEIGHT: Weight may be securely added in trunk or under the hood, but not in plain view or within the driver’s compartment must be painted white with car number. Car must weigh minimum 3000 lbs. with driver after race.




1. Any American-made stock passenger car body on a stock unaltered full frame are permitted. Chrysler and Ford unibodies are permitted. Camaros, Mustangs and station wagons are not allowed.

2. Stock appearing aftermarket plastic nose piece may be drilled for air but may not be extended with any type of material. Tail pieces with no holes are permitted.

3. Rear of car must be sealed off so that fuel cell is not exposed.

4. Spoilers (even if factory equipped), wings, skirts, valiances, air scoops, hood scoops or anything that alters the stock appearance are not allowed.

5. Bodies may be moved from the original body mount rubber bushing—no more than +/- one (1) inch and may not be less than five and one-half (5.5) inches from the ground.

6. A seven (7) inch maximum front visor is permitted. Side and/or rear window visors are not allowed. Sunroofs and T-tops must be reinforced and enclosed.

7. Nerf bars are not allowed. A maximum one (1) inch wide by two (2) inch tall steel or Lexan rub rail is permitted on each side but must be bolted flush to the body.

8. All glass, plastic, upholstery, lights, mirrors and trim must be removed.

9. Must be stock appearing. Cutting, channeling, shortening and/or modifying of the body is not allowed. Excessive trimming of fenders and/or hoods is not allowed, Holes may not be drilled in the hood for air supply. Must maintain stock OEM appearance. If hood does not match then fenders must be removeable with seven sixteenths (7/16) inch bolts.

10. All doors, fenders and window openings must remain stock appearing with OEM dimensions and be the same on both sides. Straight slab sides are not allowed. Enclosed interiors and/or decking is not allowed. Front edge of rear deck may not be more than eight (8) inches forward of center of rear-end and must have at least a two (2) inch continuous drop from front to rear.

11. Rear of dash can be no more than thirty-five (35) inches from the center of the distributor or twentyeight (28) inches from back edge of the center of stock hood. Original OEM front and rear firewalls must remain in stock location. The front firewall must match the frame used and the OEM mount must be visible. Firewall must be full and complete. Front OEM firewall may be replaced using steel fabricated firewall, 18-guage or forty nine thousandths (0.049) inch thickness. Front firewall may be no further back than the rear of oval frame hole, must be vertical and at or between twenty (24) and twenty six (26) inches tall. Interior must be completely sealed off from engine, ground and trunk.

12. Must have a complete stock OEM steel roof mounted in OEM location with OEM rake and angle for that model. GM “G” body cars may utilize an OEM fiberglass replacement roof. All openings should be covered as to isolate the driver (subject to track approval). Body should be maintained in such a manner as to keep a presentable appearance. If the body is not OEM body, steel or aluminum fabricated bodies must add fifth (50) pounds in front of motor unless wheelbase exceeding one hundred ten (110) inches.



1. Stock-type rear bumper required. Fabricated front bumper may be used with the following conditions:

a) With Aftermarket Nose Piece: Bumper may extend past frame rails for support and reinforcement. Must be behind nosepiece.

b) Without Aftermarket Nose Piece: Bumper may not extend past front frame horns. Sharp edges are not allowed. Must have a minimum five-sixteenths (5/16) inch diameter chain welded to front and rear of car and designed to allow tow truck to attach to them (may be subject to disqualification without this item). Rear bumper must be covered by the tail piece if one is utilized.



 1. All racecars must be numbered with large legible numbers on both sides, on top and on the nose and real panels. Numbers on the sides of the racecar should be in contrasting color from the body and be at least four (4) inches thick and at least eighteen (18) inches high. Top numbers should be at least four (4) inches thick and twenty-four (24) inches high.

2. Officials reserve the right, in the public image of the sport and/or the SOS, to assign, approve or disapprove any advertising, sponsorship or similar agreement in connection with any event. All cars must be neat appearing and are subject to approval of officials to compete. By competing in an event, all drivers agree to comply with the decisions of officials in this regard.



1. Must use a minimum ninety-five one-thousandths (0.095) inch wall thickness tubing with a minimum one and one-half (1.5) inch diameter for main cage and door bars. Offset cages are not allowed. Aluminum and/or other soft metals are not allowed. Roll bar connections must be properly welded. Front hoops are permitted.

2. Roll bars within the driver’s reach must be padded with an accepted material as determined by an official. Fire retardant material is highly recommended. Installation and workmanship must be acceptable to officials.

3. Three horizontal door bars on the driver’s side and two horizontal door bars on the passenger’s side (three if there is a passenger in the car) are mandatory. Must have at least three bars in front of driver and passenger in windshield area.

4. With helmet on and driver securely strapped into the racing seat, top of driver’s head must not protrude above the roll cage.



1. Frame alterations are not allowed. Full and complete frame may not be widened, narrowed, shortened, lengthened, cut, bent and/or altered in any way to change suspension brackets.

2. Rear of frame behind upper shock mounts may be replaced with round, square or rectangular tubing. 3. Right rear frame may not be narrowed for tire clearance.

4. All bars which are forward of the roll cage must be lower than the hood. 3.5 May not be cut for tie rod clearance or oil pan clearance.



1. Loose objects and/or weights are not allowed.

2. Air bags are not allowed.

3. Rear view mirrors are not allowed.

 4. Other than the gas pedal and brake pedal, any knobs, handles or levers used for adjustment of carburetor, ignition timing and/or brakes is not allowed.

5. Window nets and firesuits are required for both driver and passenger (if passenger is in car).


Floor Pan:

1. OEM floor pan may be cut six (6) inches behind front OEM mounts in a straight line across to the other side, and be replaced using steel fabricated floor pans made of eighteen (18) gauge metal or a minimum of forty-nine one thousandths (0.049) inch thick steel securely welded to the frame. If floor pan is fabricated, ten (10) pounds must be added in front of the motor. If floor pan and body are fabricated, sixty (60) pounds must be added in front of the motor.

2. Must remain flat, OEM appearing from frame rail to frame rail and no higher or lower than frame rail except for a maximum eight (8) inch tall drive shaft tunnel (like OEM tunnel size).

3. Interior must be completely sealed off from engine, ground and trunk.



1. Steering boxes must remain in stock location. All components must be made of steel, unaltered OEM and OEM location, and match frame. Tie rod end adjusting sleeve may be replaced with a five (5) inch steel tube replacement spindle with Speedway Motors raised cast part #91034501. Bolt-on OEM spindle savers are permitted.

2. Must remain on left side of cockpit (no center steering).

3. Aftermarket steering wheel and quick release steering coupling are recommended.

4. Quick steer boxes are permitted.



1. Factory-manufactured racing seats are required and must be acceptable to officials. Full containment racing seats are strongly recommended. Homemade aluminum, plastic or fiberglass seats are not allowed.

2. No part of racing seat may be further back than twenty five (25) inches forward of center line of rear-end housing.

3. Four-point quick release seat belt and harness required for both driver and passenger (if passenger is in car).



1. Front and rear suspension must be stock unaltered OEM for that make and model of frame, ball joints, spindles and all components. Alterations to any part of the suspension and/or frame is not allowed.

2. Lower control arm bushings must be OEM design and may not be steel, aluminum or greaseable type. 3. Lower A-frame mount may not be notched for clearance. Spec upper control arms with lengths of eight (8) inches or eight and one-half (8.5) inches are permitted.

4. Sway bars must be stock for make and model mounted in OEM mounts.

5. Suspension stops of any kind are not allowed.



1. Must have stock-type rubber ends and must be mounted in stock location on frame with no control arm and rear-end. Shocks may not be spaced up or down.

2. Bulb-type, threaded body, coil-over and/or remote reservoir shocks are not allowed. Air shocks are not allowed.

3. External and/or internal bumpers and/or stops are not allowed. Schrader valves are not allowed. All shocks must collapse at any time and body must be made of steel.



1. Maximum length of rear springs is fourteen (14) inches tall free height. Both sides must be equal and in stock location.

2. Springs must be a minimum of five (5) inches diameter.

3. Spring rubbers are not allowed.

4. Adjustable weight jacks of any kind are not allowed.

5. Must sit in unaltered top and bottom stock mounts.

6. Aftermarket ball joints are permitted but must be stock OEM dimensions. Rebuildable ball joints are permitted.




1. Battery boxes must be securely fastened. Adjustable battery boxes are not allowed. One battery box per car allowed.

2. Must be securely mounted inside frame rails and behind driver’s compartment or in trunk area.

3. One (1) 12-volt battery only (no 16-volt batteries).

4. Voltage generator in series with ignition system is not allowed. Voltage at distributor may not be more than at battery (12 volts).

5. All battery posts must be securely covered.



1. One (1) stock-type distributor, module and coil are permitted in stock location only.

2. All ignition parts must remain out of the reach of the driver.

4. Kill switch is required and must be within easy reach of the driver. The switch must be clearly marked “OFF” and “ON”.

5. Digital gauges and/or tachometers are not allowed. Cameras pointing to any moving or suspension parts are not allowed. Except for memory recall tachometer, electronic monitoring computer devices capable of storing and/or transmitting information are not allowed.

6. Traction control devices of any kind are not allowed.

7. Transponders must be mounted vertically behind rear of engine, less than two (2) feet from the ground and unobstructed by any metal.




1.Automotive or racing gasoline is permitted. Oxygenated fuel and/or methanol is not allowed. Additives of any kind are not allowed. Penalty for illegal fuel is loss of points, cash and awards earned for that event.

2. May not be blended with ethers or other oxygenates and may not be blended with aniline or its derivatives, nitro compounds or other nitro containing compounds. Fuel is tested using a Digitron dielectric meter. It is the responsibility of the driver and/or owner to have fuel tested.

3. Electric fuel pumps and/or fuel injection are not allowed (even if factory equipped). Fuel pump must be in stock location for make. Fuel pressure regulators and/or fuel bypass systems are not allowed.



1. Unaltered cast Holley 4412 two-barrel only is permitted (4412 must be cast into choke horn) only if using Standard Engine option (see rule 13.1). Screw-in air bleeds, powder coating and/or any modifications are not allowed. Choke plate may be removed. Maximum spacer and adapter with one (1) inch combined total with gasket is permitted. If utilizing Crate Engine option, must utilize one (1) Rochester two-barrel carburetor and a one-half (0.5) inch thick spacer between carburetor and intake is required.

2. A limit of one (1) standard fuel filter is permitted between the fuel cell and the carburetor. Cool can devices are not allowed.


Fuel Cell:

1. Must be securely fastened inside trunk and no part of fuel cell may be forward of any part of rear-end.

2. Must be visible for inspection by an official from the top through a removable stock appearing trunk lid.





1. May be a maximum of eight (8) inches wide, fifteen (15) inches diameter and made of steel.

2. One (1) inch steel lug nuts are mandatory on all wheels.

3. Bead locks and/or screws are not allowed.

4. Mud plug and wheel cover permitted on right rear only. Wheel cover must be made of plastic and be bolted. Dzus fasteners are not allowed. The ring that holds the wheel cover must be welded to the wheel in at least three places.

5. Bleeder valves are not allowed.



1. Approved, unaltered Hoosier Racing Tire asphalt F45 pull-off racing tires only are permitted.

2. Must have a durometer scale reading of 60 or higher before race Subject to inspection before and/or after race.

3. Grooving, siping, needling, metal grinding disc and/or wrapping in plastic is not allowed. Deglazing with sandpaper disc is permitted but may not leave grinding marks of any kind. Subject to inspection before and/or after race.

4. Sidewall markings must remain visible. Buffing and/or removing compound designations is not allowed.

5. 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 are not allowed.


Tire Testing Procedures:

1. Random GC (gas chromatography) scans may be performed to identify illegal substances. A GC scan should always be a peak in 19-20 minutes. If there is no peak, the driver will be disqualified. Driver may protest the GC scan results and request a mass spec test at the cost to the driver (usually around $300). The mass spec test will reveal exactly what substance was used. The main peak of the tire should never be in half.

2. Traces of chemicals and/or excessive quantities of chemicals found to be outside the baseline on any test shall result in the penalties declared in Section 4.15 of the SOS General, Rules & Procedures, plus an additional indefinite financial penalty and indefinite length of suspension. This penalty also applies to driver refusal of a tire test. Refusal of tire test shall be treated the same as an infraction. Official(s) may inspect any tire on the racecar and/or any tire in possession of the driver in his/her pit area and/or hauler (in other words, if you have “doped” tires then do not even bring them to the track).

3. It is strongly recommended that all drivers use only soap and water. Baking tires will not eliminate traces of illegal substances. The SOS will aggressively test for illegal substances and will levy severe punishment for infractions relating to tires.



1. May use any (1) one master cylinder and must have at least three (3) working brakes.

2. Aluminum and/or composite rotors or calipers are not allowed.

3. Rear disc brakes are permitted. Must use steel stock-type rotors on rear disc.

4. Right front may be blocked. Bias adjustment is not allowed. Electric and/or manual cut-off switches or valves are not allowed. Lighting of components is not allowed. One (1) manual brake shut-off valve is permitted underneath hood to the right front only (optional).

5. Aftermarket brake pedal assemblies are permitted.



1. Must be painted white and made of steel.

2. Must have a six (6) inch loop from front U-joint.



1. Any stock-type automatic or cast iron three-speed OEM manual transmission is permitted. Four-speed and five-speed manual transmissions are not allowed. Must have single disc ten and one-half (10.5) inch clutch. Flywheel and pressure plate must be made of steel. Steel bellhousing is recommended. Flywheel must weight a minimum of fifteen (15) pounds.

2. Automatic transmissions are permitted but must have stock appearing and working eleven (11) inch torque converter and cannot be smaller with ring around it. Scatter shield recommended. Aftermarket bellhousings are permitted.

3. Direct drives are not allowed.

4. Transmission coolers are permitted.

5. Mini clutches are not allowed.

6. Torque convertor must be made of steel.



1. Must be stock for make and model. Axle bearings may not be modified.

2. Brackets, control arms and shock mounts must be in stock location.

3. Trailing arm bushings must be OEM or OEM replacement with OEM design—NO ALTERATIONS.

4. May be braced for strength. Upper and lower trailing arms may be braced for strength.

5. Gears may be locked but must use unaltered stock ring gear carrier and may weld or use bolt-in locking blocks.

6. Full spools are not allowed.

7. Detroit lockers and/or torque-sensing devices are not allowed.

8. Spring cups on rear-end housing are permitted (optional) but must be welded flat on the center of the rear-end and be in line with the OEM spring mounts left to right. Both sides must match.

9. OEM spring mounts may be removed from the housing.



OPTION #1 – Standard Engine:

1. Must be stock for the make and model except big blocks and small block of more than 400 cubic inches are not allowed.

2. Cast pistons only are permitted. Must use four (4) equal valve relief flat top or dished pistons.

3. OEM crankshaft only permitted and may not be lightened. Aero wing, bullnose, knife edge, undercut and/or drilling of second or third rod throws is not allowed.

4. OEM steel connecting rods only are permitted and must remain stock OEM length, pressed pins only, weight and shape. Lightening of any part(s) is not allowed.

5. Aftermarket water pump, mini starter, pulleys, harmonic balancer and oil pans are permitted.

6. Aftermarket power steering pumps are permitted but must be belt driven. Metric cars may run a 350. 7. Stroking or de-stroking is not allowed.

8. Engine height and setback must be in stock location with a tolerance of +/- one (1) inch.

9. GM metric frame center of fuel pump must be located a minimum of one and three-quarters (1.75) inches in front of unaltered cross member.

10. Solid motor and transmission mounts are permitted. Full mid-plate is not allowed.

11. Maximum cranking compression of one hundred seventy-five (175) pounds with ignition off and engine turned over five (5) times.

12. Oil pans must have an inspection hole of at least one (1) inch diameter with nothing inside that may blocking inspection scope from seeing rotating assembly.

13. Alterations to stock oiling system are not allowed.

14. Vacuum pumps are not allowed. Turbo and/or superchargers are not allowed (even if factory equipped).

15. Hydraulic cam and flat tappet lifters only. Maximum .447 lift at valve or .298 lobe lift at cam. Must maintain fourteen (14) inches of vacuum at 1,200 RPM. Maximum 1.94 intake valve diameter, maximum 1.50 exhaust valve diameter on Chevrolet engines.

16. Hollow valve stems are not allowed. Valve springs and retainers must be stock size and shape.

17. Push rods must be stock length and diameter. Stamped steel 1.5 rockers on Chevy, 1.6 on Ford and Chrysler. Roller tips are not allowed.

18. Open chamber heads only are permitted and must be unaltered O.E.M. Porting, polishing and/or gasket matching is not allowed. The only GM head numbers permitted are 14079267, 3986336, 3986339, 3986339X, 3986388, 3932441, 376445, 3928454, 3932454, 3876487, 3973487, 3973487X, 3973493, 3951598, 468642, 330862, 333882, 3998920, 3998991, 3998993, 3998997 and 3970126. Screw-in studs and guide plates are permitted. 305 engines may use 305 heads (Vortec not allowed).

19. Intake manifold must be stock OEM unaltered aluminum or cast iron only. Aftermarket, stock high performance and/or high rise are not allowed. Bowties are not allowed. Porting, polishing, cutting and/or gasket matching is not allowed.


 OPTION #2 – Crate Engine:

 Chevrolet Performance factory-sealed CT350 Chevy small block crate engine (Part #88958602 or #19258602 or #88869602).

2. Must also run IMCA approved Rochester two-barrel carburetor. Use of a one-half (0.5) inch thick adapter between carburetor and intake is required. Carburetors shall be subject to claim, crate to crate only.

3. Must utilize soft-touch rev control box with a 6200 RPM chip. This must be out of reach of the driver but easily accessible for inspection. Any driver caught altering the chip or ignition system in any way to defeat the chip rule shall receive a 30-day suspension, loss of all track, regional and national points for the night and a $1,000 fine for the first offense. Second offense shall be a one-year suspension, loss of all track, regional and national points for the season and a $2,000 fine.

4. Must have “Crate” sticker on racecar or crate engine is claimable. Any driver running engine option #1 with a “Crate” sticker will be disqualified. Any driver running with a crate motor will not be eligible to claim in that season. Any driver that claims a standard engine and switches to crate engine will be eligible to be claimed.

5. Must be unaltered and sealed from factory at appropriate points (intake, head, timing chain cover and oil pan) with approved GM break-off bolts. Any altered, damaged or missing GPP break-off bolts will result in driver being disqualified from that event, loss of all track and national points accumulated up to, and including, the date of the offense, a $2,000 fine and a 14 day suspension from all SOS-sanctioned events.

6. Crate Engine is not subject to claim.

7. Only stock unaltered cast iron exhaust manifolds are permitted. Porting and/or grinding is not allowed. Welding exhaust pipe to manifolds or modifying OEM exhaust flanges is not allowed. Chevy center dump, Corvette, marine, LT1 or tubular steel-type manifolds are not allowed. Adaptors between head and manifold are not allowed and must be able to use all OEM exhaust bolt holes in head. Two-into-one exhaust are not allowed and X-pipes must remain duals.

8. One (1) radiator that fits in original location without body modifications is permitted. Water pump mounted fans only are permitted. Electric fans are not allowed.



1. The overall weight of the racecar must be a minimum of three thousand (3,000) pounds and shall be measured at the conclusion of the race with the driver in the cockpit, wearing complete racing apparel. 2. Any car utilizing and aluminum body must add fifty (50) pounds in front of the motor plate.

3. Lead and/or ballast may be added only in the trunk area and/or motor compartment (lead and/or ballast is not allowed in the cockpit).

4. All lead and/or ballast must be securely fastened and painted white with car number.

5. Courtesy Rule: Any car with “minor” rule infractions will be allowed to race (1) event but infraction must be determined before the race. Cars with infractions are subject to a weight penalty.



1. 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).

2. As part of their equipment in their pit area, drivers should have a fully charged dry chemical, Halon (or its equivalent) fire extinguisher. Ten (10) or thirteen (13) pound fire extinguishers are recommended.

3. Driver must wear required helmet, fire suit and five-point safety harness whenever the racecar is on the racetrack. This includes during track packing, warmups, hot laps and races.

4. Helmets are mandatory and must be certified SA2010 or SA2015.

5. Helmet must accompany driver and racecar at time of inspection.

6. Complete one- or two-piece fire suits of a flame retardant nature are mandatory.

7. Fire-resistant gloves and shoes are mandatory. Fire-resistant socks are recommended.

8. The use of a five- six- or seven-point driver restraint system (safety belts, sub-belt and shoulder harness) is required. Factory-type shoulder belts or straps are not allowed. The use of a seven-point driver restraint system is recommended.

9. Metal to metal buckles are required on shoulder and seat belts.

10. Shoulder harness must be mounted securely to the roll cage.

11. Where the belt passes through the seat edges, a grommet must be installed, rolled and/or padded to prevent cutting of the belt.

12. Driver restraint system must be less than three (3) years of age past the date of manufacture. It is recommended that the driver restraint system be no more than two (2) years past the date of manufacture.

13. Full-size window net mounted in the left side driver’s window opening is required. Window net mounts must be welded to the roll cage. All bars around the driver must have approved roll bar padding. Approved racing arm restraints are recommended.

14. Fire-resistant safety neck collars are mandatory.

15. Absolutely no plastic except from edge of firewall to body skin and inner wheel tub to body skin.




RULES: ENGINE CLAIMING RULES: Any driver in the same race on the lead lap may claim one of the top three finishers immediately after the “A” feature in the tech area with money in hand.


(A) $500.00 and swap claim on engines.


(B) Claim does not include - Flywheel, clutch/assembly, bell housing, breathers, carburetor, starter, motor mounts, oil/temp sending units, water pump, fan, pulleys, dip stick, distributor, wires, water outlet/restrictor, fuel pump, fuel pump plate/rod. 


(C) Driver may NOT claim another driver finishing in a position behind them and may not successfully claim the same driver more than once per calendar year.


CARBURETOR / DISTRIBUTOR / SHOCK CLAIM RULES: The official claiming area is in the tech area, or wherever track designates. Claim must be made immediately after the “A” feature race finishes (checkered flag). Only the driver may make the claim. Driver must have money. The claiming driver must be on the same lap as the driver being claimed. Only the top three cars may be claimed by another driver. A driver can claim another driver’s multiple claims on the same carburetor, distributor, or shock, a draw will be held with claiming drivers to determine who gets claim. Refusal to sell will forfeit all cash, trophies, and points for the night. If claim is refused, claim is NOT held against driver who made claim.


Carburetor claim $200.00 and swap, Shock or Spring claim $20.00 each and swap, Distributor claim $100.00 and swap. 


PROTEST RULE: Any driver in the same race on the lead lap may protest another car immediately after feature in the tech area. $250.00 cash per component $50.00 to the track, if legal protested car gets $200.00 if illegal protestor gets $200.00 back.