Updated Sep. 24, 1999

1. Any American made car with a-frame or factory strut suspension.
2. Minimum wheelbase of 101 inches.
3. Cars must weigh a minimum 2900 lbs. with driver in car. *See Chassis section for allowances.
4. Maximum left side weight is 58%.
5. All weights determined by Sooner International Raceway scales.
6. Any weight lost during competition cannot be replaced before crossing scales.

1. Frames may be stock, stock front clip or tubular.
2. If using stock frame or stock front clip configuration, cross members may be altered directly beneath the oil pan while maintaining stock width of frame. This is for fuel pump, balancer, or oil pan clearance only.
3. Cars with stock frames from front to the center of the differential housing will get a 150 lb. weight break. May not have front coil-over shocks and springs to get weight break.
4. Cars with stock front stub frames and perimeter chassis will be eligible for 150 lb. weight reduction. Right side frame rail must be located to the right of the front lower A-arm mounts to be considered a perimeter chassis. May not have front coil-over shocks and springs to get weight break.
5. Shocks and mounts are optional. One shock per wheel. Coil over shocks allowed.
6. Weight jacks are permitted.
7. Must have working brakes on all four wheels.
8. Rear Ends optional. Quick change rear ends allowed.
9. Must have a clutch in working condition (type of clutch is optional).
10. Torque tube allowed in automatics.
11. OEM production type transmissions. Standard transmissions must have working clutch, forward and reverse gears, explosion proof bellhousing. Automatic transmissions must have working forward and reverse gears.
12. Cars with stock front upper A-arms may deduct 50 lbs. from minimum weight.

1. Motor (#1 cylinder) may be set back no further than 3" behind the center line of ball joints.
2. Stock frame and stock stub cars may set engine back 6" from #1 cylinder spark plug to the center line of ball joints. Must not have front coil-over shocks and springs for engine set back allowance. (rear coil-overs OK)
3. No aluminum blocks or heads. Blocks and heads must be cast iron.
4. No dry sumps.
5. No roller camshafts\lifters. Roller rocker arms are allowed.
6. Ignition optional (may not run magnetos).
7. Carburetor - one 4 barrel carburetor maximum. No alcohol allowed. Racing gasoline or octane booster is permitted. No turbo chargers or fuel injection.
8. Minimum crankshaft height is 11", measured at the front of the crankshaft center-line.

1. Bodies may be steel, aluminum, or fiberglass. They must represent a stock appearing body with stock type front and rear bumpers.
2. All cars are required to have front windshield. Rear window is optional.
3. The rear of the car must be fully enclosed. No open backed cars.
4. Spoilers may be a maximum of 8 inches tall measured at the mounting point.

1. Wheels may be a maximum of 10 inches wide.
2. Tires (Towel City Retreads) are sold by the speedway. Biased ply tires are no longer available.

1. Four post cage required. Four door bars on the drivers side, strongly recommended. Snout bars, rear bracing recommended.
2. Fuel cells are highly recommended. All fuel tanks must be fastened securely in the trunk area.
3. All cars must he equipped with quick release seat belts and shoulder harness. Restraints should be fastened securely to the frame or roll cage.
4. Seats must have a head rest or high back racing seat.
5. All cars must have a fire extinguisher within easy reach of the driver. On board fire extinguisher suggested.
6. Flame retardant drivers suit, underwear, gloves, and shoes strongly recommended.
7. Helmets are required at all times when on track.
8. Window nets on driver's side recommended.
9. Roll bar padding should be attached anywhere the driver may come in contact with bars.

Released 12/6/98

1. Any U.S. factory production automobile.
2. Minimum 108" wheelbase. No tolerance.
3. Minimum weight, 3200 pounds for 362 cubic inch and smaller, 3450 pounds for 363 cubic inches and larger.
4. Cars are weighed with driver.

1. Stock frames front to center of differential housing. Upper A-frame mounts may be relocated to accommodate weight adjusters.
2. Stock components. Upper and Lower control arms, spindles, and steering.
3. Stock type sway bar, may be adjustable.
4. Springs and shocks are optional. Limited to one shock per wheel.. No coil over suspensions allowed.
5. Weight bolts are acceptable. Rear shackles may be adjustable. Lowering blocks may be run.
6. Differentials must be stock type only. May be locked. Ford nine inch differential allowed in Chevrolet or Chrysler as long as it is mounted in the factory location with factory trailing arms for that model of chassis.
7. Trailing arms must be stock.
8. No panhard bars allowed unless originally came on frame. Mounts must be stock and in stock location and must be non-adjustable. No three link suspensions. No traction bars.
9. Brakes must work on all four wheels. Must be stock cast iron calipers and rotors.
10. Transmissions must be stock. Standard transmission must have at least one forward and one reverse gear.
11. Stock OEM steel flywheel only and clutches must be in working order. No mini clutches or torque tubes.

1. Stock cast iron blocks and heads only. No aluminum blocks or heads.
2. No after market heads or intakes. No Dart or bow tie heads.
3. OEM intake manifolds. No high performance intakes allowed. May use cast iron bow tie or marine intake. Aluminum intakes must be OEM and have EGR valve port.
4. Headers allowed. Must exit out from under car and must be completely enclosed if routed through the driver's compartment. Maximum exhaust collector size, 3 inches. No zoomies or 180 degree headers.
5. Number one cylinder must not be further back than the center line of the ball joints.
6. Carburetors must be stock with no adapters or a Holly 4412 may be used with a maximum one inch adapter or Holley four barrel with vacuum secondaries only and no double pumper kits.
7. Roller rocker arms allowed.
8. No roller cams.
9. Flat top pistons only.
10. Ignition must be stock. No super coils.

1. Stock appearing full metal bodies. May be aluminum or steel. No flat sides. Hood or roof may be fiberglass. Nose and tail may be poly. Rear of car must be enclosed.
2. Front firewall must span from fender to fender and must drop as low as the frame rails.
3. Floor may be stock or fabricated. Must have rear firewall between driver and fuel tank.
4. Nerf or rub bars must not exceed 1 1/2 inches in diameter and must end flush with the body with no sharp ends.
5. Must have glass or lexan windshield or fine wire mesh in front of driver.
6. Maximum spoiler height is six inches from deck lid.

1. The track tire is a Towel City retread which must be purchased at the speedway. DOT tires must be street legal and can be bought over the normal retail counter.
2. DOT tires must be approved by the track tech crew before competition.
3. Steel racing wheels recommended. No aluminum or plastic wheels.
4. Maximum wheel width is 8 inches.

1. Must have a four point roll cage braced forward and backward. Recommend at least four horizontal door bars on driver's side. Front and rear loops recommended.
2. All cars must have a fire extinguisher within easy reach of the driver.
3. All cars must have seat belts and double shoulder harnesses. Racing type strongly recommended.
4. Must have a head rest or high back seat. Racing seat strongly recommended.
5. All gas tanks must be securely fastened in the trunk area. A firewall is required between the gas tank and driver with all openings sealed. Fuel cells strongly recommended.
6. Flame retardant drivers suit, underwear, gloves, and shoes strongly recommended.
7. Helmets are required at all times when on track.
8. Window nets on driver's side recommended.
9. Roll bar padding should be attached anywhere the driver may come in contact with bars.

Released 12/7/98

1. Any American made automobile with an A-frame suspension.
2. Minimum wheelbase 108" inches.
3. Minimum weight, 3400 pounds with driver.

1. Stock frames front to rear with no alterations.
2. Suspension components must remain completely stock. No holes may be slotted.
3. Right upper A-frame bolts may be replaced with longer bolts.
4. Springs may be changed as long as the springs interchange without having to modify the frame or suspension components. No heating or of springs (may be cut) or sway bar.
5. Minimum ground clearance of 6 inches on side frame rails with driver in car.
6. No spacers or spring adjusters of any kind inserted in between coils.
7. Shocks must be in stock location. Rear upper shock mounts may be raised to accommodate lowering of the chassis. They may not be moved from right to left. Shocks will have a $20 claim per shock.
8. Transmission must be stock.
9. Stock steel flywheel and clutch on standard transmissions. No torque tubes on automatics. Must have forward and reverse.
10. Differentials must be stock. GM in GM and Ford in Ford, etc. Must be OEM. May be locked. Spring buckets on differential must be in stock configuration.
11. Must have working brakes on all four wheels. May have four wheel disc brakes.
12. No after market brakes or brake master cylinders.

1. Stock only. No made for racing or high performance parts. If its not stock, don't run it.
2. GM in GM. Ford in Ford, ETC.
3. Blocks, heads, intake, and exhaust manifolds must be stock cast iron. No cutting, porting, or polishing. Gasket surfaces may be machined. Heads must have press-in studs only. No chevy angle plug heads. No marine or performance manifolds.
4. No pop-up pistons. No roller rocker arms or roller tips.
5. No carburetor adapters or spacers. No after market carburetors.
6. Vents may be added on the valve covers for breathing purposes.
7. Hydraulic lifter camshaft only. No solid, roller, or mushroom lifters.
8. Maximum exhaust pipe size allowed is 2" and must exit under the car past the driver.

1. Body must remain intact and all panels must be OEM steel.
2. All flammable materials (rear seats, carpet, head liner, etc.) except for driver's seat must be removed.
3. Front and rear firewalls and floor pan must be stock and in stock location.
4. Doors may be gutted only if roll cage is installed.
5. Fenders may be trimmed for tire clearance only.
6. Front fender wells may be removed.
7. Hood and deck lid may be gutted.
8. Brake and clutch pedals may not be moved from original location.
9. All glass must be removed except the windshield and rear glass.
10. All cars must have stock bumpers front and rear. It is recommended that bumpers be welded to frame. Front bumper may be poly.
11. Nerf bars must not exceed 1 1/2 inches in diameter, must be flush against body, and must not have any sharp ends.

1. DOT tires or track tire (Towel City Retread with 8" tread width) only.
2. DOT tires must be street legal and can be bought over the normal retail counter.
3. DOT tires must have a tread wear rating of 180 or higher.
4. Wheel and tire must pass through a width gauge of 10" measured at the widest point of the tire or wheel.
5. No aluminum or plastic wheels. Right front should be reinforced.

1. Roll cages are recommended (required to compete at SIR). Roll cages must be four post with at least four door bars on driver's side. All cars that do not have a cage and door bars must have a steel plate on the driver's door of at least 3/8 inches thick by 6 inches wide and must extend past each end of the door and bolted with at least four bolts equally spaced from end to end and have a roll bar.
2. Maximum 1 1/2" diameter front and rear loop bars.
3. All cars must have a fire extinguisher within easy reach of the driver.
4. All cars must have seat belts and double shoulder harnesses. Quick release belts are strongly recommended.
5. Must have a head rest or high back seat. Racing seat recommended.
6. Stock gas tanks must be removed and gas tanks installed should not hold more than 5 gallons of gas unless it is a fuel cell. All gas tanks must be securely fastened in the trunk area. A firewall is required between the gas tank and driver with all openings sealed.
7. Fire retardant driving suits, gloves, and shoes highly recommended.
8. Window nets on driver's side recommended.

Released 12/7/98

1. Compact cars only. May be front, mid or rear engine cars.
2. Weight is one pound per cubic centimeter with driver. Minimum weight for rotary engine cars is 2100 pounds.

1. Stock frames. No tubular frames.
2. Suspension components must be factory produced parts for that make. Spring shackles must be stock type. No rollers. No after market or high performance parts.
3. Shocks must be in original location.
4. Struts must remain stock and in original location. Top mounting holes may be slotted for camber adjustment.
5. Springs must be original size and in original location. May be cut or heated. Only one spring per wheel. No coil over suspensions allowed. Twist in spring adjusters must be safety tied.
6. Steering components must be factory produced parts for that make.
7. Sway bars must be factory produced parts for that make.
8. Transmissions must be stock. Must have at least one forward and one reverse gear.
9. Must have working clutch. No couplers or direct drives. No mini clutches.
10. Differentials must be stock type only. May be locked. Must use original mounting brackets.
11. Shackles must be stock type and in stock location.
12. No adjustable struts, shackles, or weight jacks.
13. Must have working brakes on all four wheels. No after market calipers or rotors.

1. Engine may not exceed four cylinders and must be in factory location.
2. Maximum 153 cubic inch (2500 C.C.) displacement.
3. No turbochargers.
4. Factory fuel injection. No after-market fuel injection systems.
5. Cars with engines that are less than 1960 C.C. may run an aluminum flywheel.
6. Origin of the engine must be from the corporate manufacturer of the car.
7. OEM intake and exhaust manifolds. No high performance systems.
8. Ignition must be stock with optional coil.
9. No gear drive timing systems on original belt timing systems.
10. Carburetors must be stock type one or two barrel only. No after-market or racing carburetors. Maximum of one inch spacer allowed between carburetor and intake. No alcohol fuel.

1. OEM full metal (steel) bodies. However body is not required to match frame model.
2. Nose and tail may be poly.
3. Stock floor board and front firewall, firewall required between driver and fuel tank.
4. Nerf or rub bars must not exceed 1 1/2 inches in diameter and must end flush with the body with no sharp ends.
5. Fenders may be trimmed for tire clearance.
6. Must have glass or lexan windshield, fine wire mesh, or bars in front of driver. All other glass must be removed.
7. Maximum spoiler height is six inches from deck lid.

1. Tires must be DOT approved, must be street legal, and can be bought over the normal retail counter or Towel City Retread treaded tire.
2. Street tires must have a tread wear rating of 180 or higher.
3. No slicks.
4. Wheels and tires must remain inside the original body line of car.
5. Steel wheels recommended.
6. Maximum width for tire and wheel is 9 inches measured at the widest point.

1. Must have a four point roll cage braced forward and backward. Recommend at least four horizontal door bars on driver's side. Front and rear loops recommended.
2. All cars must have a fire extinguisher within easy reach of the driver.
3. All cars must have seat belts and double shoulder harnesses. Quick release type. Racing type strongly recommended.
4. Must have a head rest or high back seat. Racing seat strongly recommended.
5. All gas tanks must be securely fastened in the trunk area. A firewall is required between the gas tank and driver with all openings sealed. Fuel cells strongly recommended.
6. Flame retardant drivers suit, underwear, gloves, and shoes strongly recommended.
7. Helmets are required at all times when on track. Roll bar padding should be attached anywhere the driver may come in contact with bars.

Released 12/7/98