Afton Motorsports Park Crate Sportsman Rules

The Crate Sportsman rules for Afton Motorsports Park are listed on this page.

Forms: [Driver Sponsor Sheet]


Page 1 of Rules: [Engine Specs] [Carburetor/Air Cleaner] [Ignition/Rev Boxes]
Page 2 of Rules: Go to Page 2 of Rules, Includes Exhaust/Muffler Systems, Oil Cooler/Oiling System/Enging Cooling, Drive Shaft/Rear End/Axels, Front End, Shocks/Springs/Suspension, Fuel, Fuel Cells, Bodys/Bumpers, Wheelbase/Tread Width, Wheels/Tires, Weights, Wheel Combinations.
Page 3 of Rules: Go to Page 3 of Rules, Includes Protests, Penalties and Fines, Conclusion.

[PDF of Crate Sportsman Rules] [Download Adobe Acrobat]


  1. GM (General Motors) Crate Engine part number 88958602/19258602 is the ONLY crate engines allowed.
  2. The crate engine and all it's components must remain in their stock location/configuration as purchased/delivered OEM from the factory. Any engine alterations will not be permitted, as the engine must remain as manufactured by GM. 4" inch stock bore. Overbore(s) are not permitted, however sleeve repair is permitted BUT keep in mind when done, the bore cannot be more than 4" inches.
  3. The GM 602 Crate Engine comes with factory seals. The factory seals must remain in place unaltered and as originally manufactured. Factory GM seals should not be tampered, modified, or removed. The crate engine comes this way for a reason and should not be altered in any way.
  4. GM Crate Engines come with factory seals (bolts normally) that must remain unaltered. If the GM seals/bolts are altered in any way showing tampered with, the driver is possibly subject to immediate disqualification, fines and/or suspensions.
  5. IF the GM 602 Crate Engine has been opened up for ANY REASON and either doesn't have seals or has an engine builders seal, the driver MUST provide the following information ON THE SPOT AT THE TIME OF INSPECTION: Name of engine builder that opened it, what was done to the engine by engine builder, contact information to engine builder that opened it, and paperwork from engine builder showing what was done to the engine to freshen, replace part, sleeve work, etc. If this information is not provided ON THE SPOT, driver is subject to disqualification from the event, monies, and can face up to and including suspension/fines by Afton Motorsports Park.
  6. ALL engine repairs should be done using ONLY GM 602 CRATE ENGINE REPLACEMENT PARTS.
  7. ANY and ALL parts used during repair even including gasket repair kits MUST be stock OEM GM Performance 602 Crate Engine specific replacement parts. When the replacement parts are purchased we suggest you (driver/engine builder) obtain receipt(s) from the GM Performance dealer or parts department they are purchased from. They can then be presented to officials upon request.
  8. Valves may be lapped (process to allow the valves to mesh or seat better), however further valve work or 'valve jobs' are not permitted.
  9. No machine work is permitted to the cylinder heads. If the cylinder head requires any sort of resurfacing or valve seats, a new cylinder head may be required. (Please note: If for any reason repairs are needed to the GM 602 Crate Engine in regards to ANY sort of cleanup to make the head set flush or 'True' on the block, please contact Afton Motorsports Park officials prior to the work being done to verify it will be permitted under series rules via tolerance. As a driver you may also want to be in contact with your local track as well.)
  10. Any altering, polishing, blasting etc. to the intake manifold and/or cylinder heads is not permitted.
  11. The distributor must remain factory stock as manufactured by GM for the 602 Crate Motor. The distributor advance curve must also remain stock. No welding solid.
  12. ANY AND ALL engine repair work MUST be documented, retained, and turned in to GRIT Racing Series officials to be entered in the engine maintenance database. Also keep in mind, ANY AND ALL engine repair if deemed necessary should be resealed by engine builder! There is no reason to not have seals on a GM 602 Crate motor of some sort. If there is any question, DO NOT HESITATE TO ASK FIRST.
  13. Track reserves the right to request further technical inspection by track officials and/or via assistance from appointed tech inspectors on an alternate or neutral site.
  14. GM 602 Crate Motors are intended as a cost effective engine package for the Sportsman Modified division. It provides an affordable racing program for teams to avoid unnecessary additional costs via rebuilding, balancing, porting, polishing, and other bells & whistles more suited for 358 Modified competition, not Sportsman competition. Maintaining the integrity of the GM 602 Crate Sportsman engine program is our goal with the rules set within. No alterations, modifications, balancing, polishing, machine work, blue printing, or any alteration to improve a drivers competitive edge is a clear violation of the rules and integrity of the GM 602 Crate Engine and will be dealt with swiftly and with penalty.
  15. O) Final judgment and/or decision of a driver's legality according to Afton Motorsports Park rules will be at the discretion of Afton Motorsports Park officials.

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Carburetor/Air Cleaner

  1. Holley 650 cfm carburetor part number 4777 or 80777 is legal. The carburetor must have the stock venture and throttle bore dimensions. It must maintain all stock dimensions including mounting and stud location on the intake manifold. Booster heights must remain stock OEM from Holley. Cutting, tumbling, and/or polishing are not permitted, as it must remain stock OEM from Holley. Any visible clear modifications to gain competitive advantage that are not stated within the rules will not be permitted. Maximum height of carburetor measured from bottom of carburetor (throttle plate) to horizontal surface of the block must be 7" inches in both front and back of block. Only a single unaltered square hole/opening carburetor spacer plate with a maximum thickness of 1 1/8" inches with gasket is permitted. NO tapering, machine work, or any other alteration to the spacer place is legal. THE FOLLOWING ALTERATIONS/WORK MAY BE DONE: Drilling holes in the throttle plate to help proper idle. Drilling, plugging, or taping of any unused vacuum ports. Welding of throttle shaft to linkage arm. Choke plate and shaft may be removed. Center carburetor body metering block surface may be milled no more than .015" on each side. Idle and/or high-speed air correction jets may be drilled. Jets may also be changed as needed or preferred. NOTE: The gauge measurement or go/no-go gauge must be met and pass at all times regardless of the carburetor temperature.
  2. Holley 650 cfm HP 80541-1 carburetor is also legal. The carburetor must maintain all stock dimensions/measurements including mounting and stud location on the intake manifold. Only specified Holley replacement parts for the HP carburetor may be used for any adjustments or repair. You may adjust the jets, bleeds, needle, seat, emulsion bleeds, power valves, accelerator pumps, accelerator pump cam, and nozzles. Alterations of the carburetor, its parts, or any machining/reshaping are not permitted. Coatings of any kind or epoxy are not permitted. Only a single unaltered square hole/opening carburetor spacer plate with a maximum thickness of 1 1/8" inches with gasket is permitted. NO tapering, machine work, or any other alteration to the spacer place is legal. NOTE: The gauge measurement or go/no-go gauge must be met and pass at all times regardless of the carburetor temperature.
  3. Tne standard round type air cleaner is permitted. Any air cleaner that provides ventilation through the top cover (such as the K&N style air cleaner) is permitted. Any ram air or tin that directs the flow of air directly to the air cleaner above and beyond the normal manufactured fiberglass hood piece is not permitted. The air cleaner must remain in place when the hood is removed. If the air cleaner has to be removed to remove any piece/part of the hood or tinwork it's not legal. Any inserts or other devices that flow air directly to the carburetor or the air intake is not permitted. No air diffusers.

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Ignition/Rev Boxes

  1. Only stock OEM distributors as manufactured by GM for the 602 Crate Engine are permitted. The distributor must maintain the factory stock mechanical advance curve according to OEM specifications. Any alterations and/or adjustments are not permitted
  2. Only stock OEM H.E.I. ignition coils are permitted. No trigger or crank trigger type ignitions are permitted. ONLY stock OEM H.E.I. replacement ignition coils are permitted. NO AFTERMARKET. The ignition must be mechanically driven and remain in the stock location.
  3. Only one standard sized 12-volt battery with top or side mounted terminals is permitted. Any step up transformers or devices designed to increase voltage are not permitted. The battery voltage must not measure more than 14.3 volts if checked.
  4. OEM stock GM 602 Crate Engine firing order (which is 18436572) is required on all engines.
  5. We are requiring the use of a REV BOX and it must be unaltered and working. The MSD rev box part number 87286 or 8727CT must be mounted under the hood out of the reach of the driver and easily accessible for inspection. Please make sure the black wire is grounded to the motor and when the hood is removed the rev box should be clearly visible and not hidden/covered. It MUST BE operational prior to and after each racing event with a maximum 6200 chip (6200 RPM). Rev boxes with the RPM limiting chip can and will be inspected and again MUST BE UNALTERED IN ANY WAY WITH A MAX 6200 RMP CHIP OPERATIONAL and MOUNTED IN THE CAR. No exceptions.
  6. Gear rule may come into play at tracks discretion on the 2016 schedule.
  7. Traction control or braking devices that control traction of any kind are not legal.

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