Afton Motorsports Park Street Stock Class Rules

The Street Stock class rules for Afton Motorsports Park are listed on this and four other pages, linked to below.


Page 1 of Rules: [Go to page 1] Includes Eligibility Requirements, Former Prostock/Super Stocks, Bodies and Aluminum Body Rules.
Page 2 of Rules: [Go to page 2] Includes Seats/Interiors, Roll Cage and Suspension.
Page 3 of Rules: [Go to Page 3] Includes Drivetrain, Weight, Wheels and Tires, Brakes, Shocks, Transmission and Engine.
Page 4 of Rules: [Vortec Head and Intake Option, Section A - B] [Vortec Head and Intake Heads] [Air Filter] [Pistons] [Rods] [Crankshaft] [Headers] [Intake] [Ignition] [Cooling System] [Fuel System] [Carburetor] [Option 602 Street Stock Engine]
Page 5 of Rules: [Go to page 5] Includes Body Installation Guidelines Diagram.

[PDF of Street Stock Rules] [Download Adobe Acrobat]

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  1. Allowable heads must have casting number Vortec heads, stock heads, World Product, or Stock GM heads with 2.02-1.6 valves. Vortec heads will have 1.94-1.5 valves.
  2. Vortec heads allowed are: # 10239906, 12552520 and 12558062. (No aftermarket Vortec heads).


  1. No open air filters through the hood of any kind.
  2. Optional aluminum intake for Vortec Head ONLY. GM p/n 12366573, Vortec 2116, Edelbrock 7116. You must use BRP 377 carb adaptor.


  1. Flat top pistons only.
  2. No domed pistons of any kind.


  1. Any steel rod.


  1. Crankshafts of stock dimensions, weight, and style must weigh 45 lb minimum. Balancing of rotating assembling allowed. Stock stroke only for make/size of engine. No altering of stock stroke crankshafts allowed.

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  1. Crossovers are allowed but no 180 degree headers are allowed.
  2. No exhaust can run thru driver's compartment.
  3. All headers must exit underneath car with exhaust pipes exiting past driver and end before rear tires with no crankcase evacuation type systems.
  4. No two into one exhaust or H pipe connections in exhaust systems.
  5. Mufflers recommended.


  1. Stock cast iron production 2 Bbl OEM intakes. Edlebrock 4B intake allowed.
  2. No marine, bowtie, TBI or other industrial intake manifolds.
  3. No propane intakes allowed.
  4. No porting, polishing, or any internal work.
  5. No shot blasting, acid etching, or other cover up work allowed.
  6. No plenum area work at all other than to mill carburetor mounting surface to remove rust. A 1" tall fiber or aluminum carburetor adapter may be used to adapt to Holly 2bbi carb.


  1. OEM style electronic ignition systems only.
  2. No aftermarket ignition systems such as MSD, magneto,etc. No traction control, or timing altering devices allowed.
  3. No crank trigger ignitions or multi coil systems.


  1. No electric water pumps.
  2. Pump mounted fans only, no electric fans.
  3. No flex fans or aluminum fans.
  4. Any pulleys allowed.
  5. Any radiator but must remain in stock location.
  6. No duct systems designed to direct air to intake/carb.


  1. Gasoline only. Maximum of 22 gal. fuel cell with foam and rollover valve mandatory.
  2. All fuel lines running thru driver's compartment must be steel braided with no pipe fittings and routed in a safe manner away from exhaust header.
  3. Fuel shut off must be well marked and within driver's reach.
  4. Mechanical block mounted OEM fuel pumps only.


  1. Limited to one stock 4412 Holley 2bbl carburetor.
  2. All carburetors must pass all no-go gauge checks with body, base plate, boosters, throttle shafts, etc all being unmodified and in stock location.
  3. No polishing of any part of carburetor.
  4. No modifications to pick up air from any source other than through top of carburetor, such as cut gaskets, drilling, etc. Only the following changes may be made to carburetors: jets, power valves, air bleeds, emulsion bleeds, float, needle/seat, pump/cam, idle bypass holes in butterflies, plugging/blocking of vacuum ports, welding linkage to shaft, installing shaft bushings to correct for worn shaft, and boosters may be tightened for safety.



  1. Only a General Motors Spec. #19258602. I.D. Plate must be accessible.
  2. Stock Rocker arms that come with motor only.
  3. OEM style fan and water pump crank driven.
  4. No electric fans and clutch fans.
  5. No evacuation pumps of any kind. Mechanical, electrical or otherwise not allowed. Engines must pull a minimum of 19 inches of vacuum at idle.
  6. Replacement valve spring part # GM10212811.


  1. No Tri-Y headers.


  1. HEI distributor that comes with motor.
  2. Must have MSD Rev Limiter # MSD87286 with 6200 RPM chip. Rev box chip must face up and be taped into the rev box. This must be hooked up and working at all times. If found to be higher than 6200 RPM chip, you will lose purse and points for that event, and a fine of $500.00 must be paid before racing again.
  3. MSD must be out of reach of the driver. All wiring to REV Limiter box not permitted to be in a harness.
  4. All wires must be clearly visible.
  5. Rev box must be under hood and be easily removed to tech purposes.
  6. No Cockpit mounts. Must be out of reach of driver.
  7. Rev boxes may be confiscated or swapped by speedway officials.

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