Pure Stock Four Cylinder Rules

2013 PURE STOCK FOUR CYLINDER NATIONALS RULES

BODY AND CHASSIS SPECS

  1. Any stock appearing metal bodied four cylinder car or truck –1965 thru the current year.
  2. The body, body mounting position, and overall appearance must retain all stock OEM dimensions and original body lines and contours and must be centered over the wheels. The body must be made from magnetic steel, unless otherwise stated. You may run fabricated doors, front fenders, and hood: but they must appear stock and be securely fastened. No flat sides. The doors and front fenders must be magnetic steel or aluminum. You may run a composite hood.You may use Five Star or Performance Bodies replacement panels. No MD3 type components. The roof, roof post, and rear quarter panels must be stock. If the rear quarter panels are damaged, you may fabricate a new panel over the existing, with the same contours. No other alterations to the body allowed.
  3.  Stock appearing bumpers on the front and rear, may use an aftermarket nosepiece and rear bumper cover. Must match make of car, if applicable.No open rear ends or flat metal panels. 
  4. A minimum of 6” ground clearance must be maintained on the nose and side rocker panels. Skirting allowed, maximum width 6”. May conform to stock rocker panel.
  5.  Boxed-in interiors permitted behind the driver’s seat only, but must have a removable inspection panel. Entire floor pan and firewalls must be un-altered.
  6. The front firewall must have all openings covered incase of fire or fluid leak in the engine compartment. The rear firewall must be covered with sheet metal or aluminum to separate the driver’s compartment from the fuel cell area, but the existing firewall must remain intact. Do not gut the inner trunk, tubs must remain over rear tires.
  7. The front, main, and rear chassis rails must remain in the car and un-altered. You may tie the uni-body chassis together. Absolutely no bracing under the car. If damaged, the front chassis rails may be replaced with tubing in front of the cross member. The sway bar may be connected to this tubing, but no other suspension components. If damaged, the rear chassis rails may be replaced with tubing behind the rear end housing.
  8. All cars must maintain the stock wheelbase. Rear wheel drive cars only.
  9. Must have the make of car, the required weight and C.C.  on the hood or front fenders.
  10. Rear spoiler height is 6” maximum of surface material above the trunk lid. No side spoilers, rudders, or support braces. No roof or fender mounted spoilers or fins.
  11. Windshield is optional, if removed, you must have fiveprotective bars on the driver’s side. They must be between 4” and5” intervals. They must be magnetic steel. No front side door windows allowed. You may fill in rear side openings, if applicable.
  12. All 2000 C.C & under – 2000 pounds minimum.  Over 2000 C.C – 2300 pounds with the driver after the race.

ENGINE SPECS

  1.  The engine maximum is 2500 C.C.
  2. Engine must be in stock location, this means factory height and setback. You may run solid motor mounts, but they must be stock size.
  3. No decking allowed on the block, may surface the top of the block to a maximum of .010 Must be a factory production steel block. All components of the engine must be stock production for the serial number of the block, unless otherwise specified.
  4. Must use a stock oil pan, no modification. May relocate the oil filter. No oil cooler.
  5. Engine may be balanced, but no stroking or de-stroking of the engine.
  6. Stock crankshaft and rods, no modification of any kind. 
  7. Stock factory type cast pistons only. OEM factory stock cast replacements permitted. They must match CLR templates. No alterations to the pistons, except for valve clearance.
  8. Stock type clutch and flywheel. May surface only, no other modifications.
  9. Stock production head and intake. No porting, polishing, acid washing, or alterations of any kind. No spacer between the head and the intake. No fuel injected parts of any kind. No factory dual plug heads. One spark plug and two valves per cylinder maximum.
  10. Stock size valves, no cutting for valve springs. No aftermarket double valve springs. May use factory stock double valve springs.
  11. No cutting the lifter boss or other alterations, for the purpose of making a solid lifter. Must remain fully hydraulic, unless engine was not hydraulic originally from the factory. Must run factory stock lifters, may not be altered in any way. No lash caps, but may have maximum two(2) lifter bosses with a single washer .025thick maximum to account for uneven bore depth. 
  12. Aftermarket timing gear allowed to match cam key type,may be externally adjustable.  No aftermarket timing covers (must be one-piece). No roller cam or rockers. Maximum 450 lift.
  13. Holley 500 CFM (4412) or Holley 350 CFM (7448) must be used. No modification, except for choke housing. It must pass the track tool. Maximum 1” spacer / adapter allowed to fit the carburetor to the intake.  May cut intake to match adaptor bore sizes.
  14. Mechanical or electric fuel pump permitted.
  15. Must run a factory stock distributor and ignition system. No magnetos and dual point distributor. Must have an operable starter in working condition.
  16. Headers permitted. An un-altered Schoenfeld part # 112530 muffleror equivalentmust be used. Must use a 3” to 2.5” reducer with a minimum 12” long X 2.5” diameter exhaust pipe beyond the muffler. We will allow a one week grace period on the muffler part number and exhaust pipe.

SUSPENSION SPECS

  1. Transmission and differential must be stock manufactured OEM production. The transmission must have a minimum two forward gears and one reverse, plus neutral position. You may weld the rear end gears or run a spool, but no other aftermarket devices. Must have four wheel working brakes, no adjusters or shut-offs allowed.
  2. All cars must have an approved scatter shield and / or approved bell housing.
  3. All suspension components must remain stock in their OEM mounting locations for the year make and model of the vehicle.
  4. The steering shaft may be a collapsible shaft. Aftermarket steering wheel and quick release are permitted.
  5. Must use stock type magnetic steel shocks bolted in the stock location. No adjustable shocks. No coil spring attached to the shocks.
  6. Springs must be in the original position. You may run aftermarket springs, but you may not modify the spring bucket in any way.
  7. No screw jacks or wedge bolts. May run adjuster cups.May run spring rubbers and shims.
  8. No shackles. Lowering blocks permitted. Stock type OEM multi-leaf style springs must be magnetic steel.   
  9. Strut cars must run stock or OEM replacement components, may brace top of tower. May alter the top of the strut tower with a slotted plate for the purpose of setting caster and camber. The strut towers must remain intact for support.
  10. Stock front and rear sway bars only, no adding of additional devises. No other adjusters allowed.
  11. Any steel wheel 8” wide X 13” maximum. May run an 8” X14” maximum steel wheel with the D.O.T. radials. Bead lock rims permitted on the right side only. Safety beads required on all wheels. One inch lug nuts recommended. No wheel flares.
  12. Racing fuel or pump gas only. No alcohol or additives.
  13. If it is not mentioned in the rules, it must be factory stock.
  14. Cars will be inspected for tech and safety items prior to competition. Track official has the final approval.    Safety rules can be found in the 2013 General Rules section.
  15. A tire rule will be enforced – Towel City Retread 205 / 60 / 13 (77 compound) or a D.O.T. approved street radial. 

 

For any tech related questions, please call Four Cylinder National Tech Inspector, Garry Wilson at 919-614-1703.

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