2021 STOCK OPEN WHEEL MODIFIED RULES

2021 STOCK OPEN WHEEL MODIFIED RULES 

 NO CARBON FIBER. NO TITANIUM UNLESS OTHERWISE NOTED. NO BUMP STOPS. NO BUMP SPRINGS OR CHASSIS LIMITERS. NO TRACTION CONTROL DEVICE(S) OF ANY KIND.

CAR: American made, factory production, 1970 or newer with parallel frame, rear wheel drive only. Minimum wheelbase 108”. Wheelbase must be within 1/2” side to side.

Chassis:

  1. A. OEM stock for chassis clips or fabricated / tubular frames (must be approved by tech.)
  2. Frames may not be widened or narrowed and must be able to support roll cage on both sides. Front cross member may be notched for radiator clearance only. No widening or fabricating of cross member. Must maintain stock measurement from cross member to A frame bolts.
  3. Fabricated clip cars must have 50 pounds in front of flywheel.
  4. D. Ride height minimum of 4” to body, frame and lead at all times. No pulling up on car in tech line.
  5. MODIFIED TUBE CLIP. Must use stock lower A-Frames, steering box and idler arm. Must maintain 3-¼” from lower control arm bolts to bottom of cross member at all times. Lower mounts must be solid and non-adjustable. Must measure 17” – 1/4” tolerance from center bolt to center bolt on front side of lower control arm and 27” – ¼” tolerance. Any tube clip that does not meet the specs will be deemed illegal.
  6. F. Adjustable Idler arm allowed but MUST be mounted in stock location.

 

BODY:

  1. Width 66 inches maximum length 120 inches maximum measured from front of door / back of engine block to the end of rear quarter at any point. 6” maximum body rake. Maximum 3” at door and 3” at quarter to get the 6” total. Body must be mounted straight on chassis.
  2. B. Firewalls can be aluminum and floorboards are to be made of steel only.
  3. Fiberglass, aluminum or steel duplicates of body parts are permitted.
  4. Full roof is mandatory and must cover complete halo bar. Maximum of 21-inch drip rails allowed.
  5. Original roof line of vehicle should be maintained with a maximum of 1” drop rear to front.
  6. No wings, ledges or other ground affects anywhere inside or outside car.
  7. Rear spoiler allowed 6“x 60“only.
  8. Engine compartment will remain open, no side panels. Hood sides may have a maximum of 6” drop and be enclosed at the rear of the hood. Bodies should extend no further than back of the block. NOTE: (passenger side of body must be no further forward then the rear of the block).
  9. I. Lower rear quarter panel turn not to exceed 1 inch maximum with a maximum of 2-1” braces/supports. Quarter panel minimum height from top to bottom in rear is 18”.
  10. Maximum front nose width 43 1/2”

 

ENGINE:

  1. 350 block only two bolt or four bolt main block. 350 cranks only. Builder option. No studded blocks. 060 maximum overbore +.010, zero deck builders’ option. No grinding in block, screens OK. No overbore of lifter holes or repairs.
  2. Heads stock open chamber head with stock valves and 100 lb seat pressure or EQ heads with IMCA hobby heads 76 cc 1.94 intake and 1.50 exhaust. Three angle valve job allowed. No bowl cutting, flat cut only 72 CC chambers, Diameter equals 1.250 maximum diameter. Stock rocker nuts and balls. World Products 4360KA heads Legal as well
  3. C. Any flat top 2 or 4 eyebrow piston. Pistons may not stick out past top of block.
  4. D. Rods 5.7 rod length (stock OEM) only for engine used. No aftermarket. No stroking or de-stroking of engine allowed. No H-beam rods.
  5. Crank-GM cast crank 48 lbs no knife edge. Balancing OK. Stock stroke and weight for engine used.
  6. Camshaft 390-410 lift cam with 650 Quadrajet allowed or 450 lift cam max with 500 cfm Holley 2 barrel (4412) Must pass track gauges. Camshafts may be degreed Stock rocker ratio for engine used. 1.5 GM steel rockers OEM lift will be checked out at rocker. No stud girdles. Screw in studs and poly locks OK. Stock OEM GM lifters. May run double roller chain, non-adjustable gear.
  7. Intake. Stock cast Quadra- jet or may run performer 2101 series intake. No bowtie, Corvette or boat intakes allowed. (Maximum 1” carb spacer.) NO Air box to carb or air cleaner.
  8. Distributor stock only GM HEI (NO MSD boxes).
  9. Push rods. stock diameter.
  10. Water pump steel or aluminum. Stock harmonic balancer or, OEM GM for engine used. Oil pan, valve cover and pulley builder’s option.
  11. K. L88 flywheel OK 14 lb minimum
  12. 602 steel head GM crate motor allowed with 500 CFM Holley 4412 carb. Or Holley 650 4150 Part # 80541-1 0nly.
  13. Built 350 or 602 crate motors. Per rules. (604 engines with 602 heads & intake NOT allowed). (No 603 crates)
  14. N. 602 Crate may use aftermarket oil pan for ground clearance
  15. Exhaust system must be mounted in such a way to direct spent fumes away from the cockpit of vehicle and must extend past frame rails and away from all areas of possible fuel spillage. All headers are allowed.
  16. Rear of the engine (bell housing flange) must be mounted at least 72” forward from the centerline of the rear axle. Engine offset must be kept within the front stub. Engine offset maximum of 2” of centerline of front cross member. Crankshaft minimum height will be 11” from the ground to the center of the crankshaft. Must be wet sump only. No totally dry sump systems allowed. Wet systems must be operative.

 

Engine Blocks:

GM 350

Ford 302, 351

Chry. 318, 360

 Heads:

GM 72cc min.

Chry. 64cc min.

Ford 60cc min.

Stock Diameter valve springs for heads used.

100 LB max seat pressure

TRANSMISSION:

  1. Saginaw 3 speed or 4 speed, Muncie four-speed and turbo 350-400 automatic transmission allowed. 10” inch minimum torque converters. No lock up converters. No five speed transmissions, No in/out boxes. No buttons or couplers. Must all be clutch operated with motor running and car still in position. Driver must be able to engage car in gear and move forward, then backward at time of inspection. Clutch must be inside bell housing. Must have all gears working and reverse. No lightweight parts or straight cut gears.
  2. B. Clutch size minimum 5 1/2 inches. Must add 50 lbs for any clutch smaller than 10” inches.
  3. C. Stock OEM transmissions allowed; Power glide transmission allowed. NO RACING TRANNY’S ALOUD

 

DIFFERENTIAL:

  1. 9-inch floater or quick change. 10 or 12 bolts
  2. B. Wide 5 hubs allowed with bolt on front adapters to stock spindle, stock lowers only. Must remain in factory location.
  3. No rear sway bar.

 

WHEELS & TIRES:

  1. Any 60 or 70 series DOT tires with minimum tread-wear rating of 400. Must be seen on tires. Tires may be cut or trued. No tire soaking allowed. Hoosier H500 is also approved
  2. Wheels maximum with 8 inches. Steel only. Must be racing wheel. Tires must not to be outside Nerf bars.
  3. 80-inch tread width maximum outside to outside. No tolerance.
  4. D. No bleeders

 

ROLL CAGE:

  1. Must consist of continuous hoops, not less than 1-¾” outside diameter must have a wall thickness of atleast .095.
  2. Must be frame mounted in at least 6 places.
  3. Must consist of configuration of front and rear hoops connected by tubing on the sides or side hoops. Drivers heads must not protrude above cage with helmet on and strapped in driver seat. Roll cage must be securely supported and braced.
  4. Protection of feet is mandatory. Bar across back of engine with vertical bars and rub rails or similar protection.
  5. E. No brace bars forward of cage may be higher than stock hood height.
  6. Driver door bars must be as parallel with the ground as possible and located perpendicular to the driver so as to provide maximum protection for driver without undue difficulty in getting into or out of vehicle. Sidebars must be welded to front and rear of metal cage members. Door bars less than .095” thickness should have 4 bars at least 1-1/2” diameter. Must have steel plate covering driver’s door area.
  7. Must have five-point harness with date specifications.
  8. Window nets Mandatory

 

BUMPERS:

  1. Must be used in both front and rear. Front bumper should be mounted frame end to frame end with bottom loop parallel to the ground. Should be made of 1-1/4” pipe and must be welded to support car if lifted by wrecker.
  2. Rear bumpers. Nerf bars. And bodies must not extend beyond width of the rear tires and must not contain any sharp edges.
  3. Rear bumpers may be constructed of pipe, flat stock or Aluminum I-beam and must protect fuel cell. Center bumpers front and rear must be 18” (plus or minus 2” from ground.

 

FUEL CELL:

  1. Maximum of 22-gallon fuel cell mandatory. Cutting of trunk for the fuel cell is permitted. Fuel cell must be in 22” gauge steel.
  2. Sunoco spec. fuel optional

 

DRIVE SHAFT:

  1. A. Must be steel driveshaft ONLY. NO aluminum or carbon fiber

 

SUSPENSION:

  1. Stock passenger car spindles only. No fabricated spindles. Center of ball joint to center of tie rod must be stock measurement as well as the same measurement on both sides.
  2. OEM Bottom A-frames cannot be moved. Ford lowers are allowed as long as they mount in stock mounts.
  3. C. One piece OEM or aftermarket sway bar only.
  4. D. No coil over shocks. Either front or rear. Coil over eliminators must be used in rear only with minimum spring diameter of 4-1/2”.
  5. No fiberglass springs allowed. No torsion bars allowed in rear.
  6. No hydraulic. Ratchet or electric weight jacks anywhere in or around car.
  7. One shock per wheel only. Steel nonadjustable and non-rebuildable shock only. No Schrader valves. Adjustable shafts and canisters are not permitted. No Aluminum shocks permitted. No split valving must be same up and down. ($100 claim rule per shock). Shocks Must Be Straight up 3 to straight up 7 ONLY Meaning 3 up 3 down, 7 up 7 down NO Gas shocks H. Heim joints on inner and outer tie rod OK. No racks.
  8. I. Front rotors may be re-drilled for larger studs or different lug pattern but may not be lightened.
  9. Front Coil Springs will be 500lb minimum. No exceptions.
  10. No lift bars allowed. No exceptions

 

 COMMUNICATIONS:

  1. Raceceivers required.

 

WEIGHT:

  1. A. 2650 minimum weight
  2. Weight can be checked at ANY time before, during or after time trials and or racing event with driver sitting in the normal driving position with helmet and fire suit.
  3. Tube clip cars must add 50 pounds in front of flywheel.
  4. Stock clip cars 2650lbs, small clutch adds 50lbs = 2700 lbs total. Tube clip cars 2650lbs, with 50lbs in front of flywheel, small clutch adds 50 lbs = 2700 lbs

 

BRAKES:

  1. Brakes must lock up all 4 wheels during post inspection. All 4 brakes must work.
  2. Front and rear brakes must consist of stock appearing components single piston only. (Aluminum ok)
  3. C. May run steel or aluminum front safety hubs. May run after-market rear hats and rotors
  4. Brake Bias ok to run.

This is a protest division. Refer to General Rules for Protest fees.

PROTEST MUST BE SUBMITTED IN WRITING AND FEES PAID TO TECH WITHIN 10 MINUTES OF RACE COMPLETION (NO EXCEPTION). Must finish on the lead lap. Tech discretion

The track reserves the right to add weight at its discretion for the fairness of competition.

***The rules are in addition to the “General” track and safety rules. It is your responsibility to know the rules. A claim of “I didn’t know” or “you did not specify” will not release you from the liability of the rules. Tech inspection has final say on all issues, and that call is not reversible. If it does not say you can do it- do not do it. If you feel a rule is not clear – ask questions- rules are not open for personal interpretation. ***