PQS Rules 2026-2027 Season

PQS rulebook.

General Rules

A. Track official’s decision will be final. Any disagreement on their decision on any point of controversy will result in immediate disqualification for that class for the entire weekend. B. Your tractor must meet all safety and shielding requirements prior to hooking, otherwise you will not be allowed to compete and there will be no refund of entry. C. There will be four track officials at all PQS Events. These four officials have the final say on what happens on the track. Their jobs are as follows: - Flag Men: There will be two flag men at all PQS events. A starting line flag man, and a finish line flag man. Both flag men are responsible for giving the green flag to start a run, determining number of attempts made by a puller, determining if a puller is in bounds, determining if a puller lost a part during a pull, and ending a pull with a red flag when either forward progress has been lost or a puller is getting out of control/safety issue arises. - Starting Line Official: The starting line official is responsible for keeping pullers in order and ready to pull, tracking time in the event of a dropped hook or on track delay, keeping track of/determining number of attempts made by a puller, determining if/when a sled reset is needed, and placing a dropped puller into their proper place in the lineup. - Sled Operator: The sled operators responsibilities include safe/fair sled settings, determining if/when a sled reset is needed, and can also end a run if a puller is getting out of control or a potential safety issue arises. D. A drivers meeting will be held prior to each days event. This meeting is mandatory. E. No person is allowed in the “no mans land” at any time during the pull. Track maintenance return lane is not to be entered at any time. F. Anyone entering the “Hot Zone” must sign a release forum. The hot zone is considered the pit area around scales, staging area, and assisting a puller on or off of the pulling track. G. Drivers under 18 years old must have signed parental consent on file. H. Obvious or excessive consumption of alcoholic beverages or drugs will be grounds for disqualification.

Track Operations

A. The tractor must be in neutral and hand pushed both onto the track and to the sled. It may only be put in gear once it is hooked to the sled. The tractor must be shut down before the chain is unhooked from the sled. B. No portion of the tractor shall interfere with the sled, chain, or hitch during the pull. NOTE: Many times the starting line becomes torn up, which will cause the front of the tractor to be lower than the rear tires. This may cause an interference of the cross bar for the wheelie bars/wheels. The intent of the rule is not to interfere once the pull is underway. C. Any portion of tractor touching boundary line during pull will result in disqualification. This would be limited to the front or the rear tires. Once the tractor is beyond any track markers there is no longer any out of bounds. NOTE: Flag men have final say for this rule. D. Two attempts will be allowed to start sled in qualifying heats and in the finals. One attempt only in a pull-off. NOTE: An attempt is considered once the hook goes in the hitch and the driver physically tries to start the tractor in motion by revving up the engine and attempting to release the clutch. Flag men & Starting line official have the final say in determining what is considered an attempt. E. The first puller in any heat or finals can drop to the 6th position or come back immediately. F. If a puller has a mechanical problem, they have to drop back 6 positions (five more pull then they hook). If there are less than five tractors remaining, they have until the end of the heat plus five (5) minutes. This timer will start when the sled has returned to the starting line. If they are not able to hook within the allotted time they will receive last place in that heat. The puller CAN NOT drop to another heat. G. If the first puller in a class does not make an attempt due to mechanical issues, the next tractor to hook will be considered the first puller and will have the first puller drop option. However, once the first puller has hooked to the sled and the sled has been moved (even as little as one inch) that attempt is considered the official first pull, and the drop option cannot be reassigned. If a breakdown occurs, the puller may fall back up to five positions for repair (see Track Operations section F). Since this constitutes a repull and “start over,” the puller will also retain the option to drop an additional five positions from that point if repairs are still required. H. If any puller withdraws due to mechanical reasons before hooking to the sled and cannot compete repairs within the normal allotted time (see Track Operations section F), that puller must drop completely from the class. I. Driver will be disqualified if he or she delays contest. J. A puller is expected to have their tractor running by the time the sled gets back to the starting point. If the puller delays more than 45 seconds he will have to drop. (see track operations section F) K. Pulling position will be determined by drawing. The drawing should be done prior to the event for the heats. L. Driver must remain seated during pull. Drivers must have at least one hand on the steering wheel at all times. M. Weight transfer sled will be used. Must be a 3 foot chain with the hook point within 2 inches or less of the ground. All sleds should be NASOA certified. N. Tractors must be operated in a safe manner at all times O. All weights must be safely secured to the tractor. Any excessive or obvious loss of weights or components may be cause for disqualification. The flagman must make the call during the pull. Any disqualification for loss of weight or components must be made during the pull. A pull is started when the sled starts to move and is ended when the sled stops movement, even though the tractor may still be under power. P. PQS Track officials have the right to restart the class anytime within the first five hooks of a heat or finals (5), either for full pulls or short tracking. Heats or finals may be restarted sooner if the sled setting causes a concern for safety. Q. A tractor can only enter one time per class. R. A tractor engine can only pull one time during the finals, cannot be switched from one tractor to another - AKA “The Black Nichols Rule”. A puller is able to put in a backup engine, but not from another tractor pulling in the same finals. S. If the driver leaves when the red flag is still displayed, it will be cause for immediate disqualification for that class even if it’s before the 75’ mark as it’s a safety issue. T. Flagging procedure at start line: At pulls where a starting line flagman is present, the driver must reference the starting line flagman to begin their pull. Even if the finish line flagman is displaying a green flag, the driver may not start until the starting line flagman also displays a green flag. - The order of green flag signals will be as follows: - Sled Operator - Finish Line Flagman - Starting Line Flagman (Puller takes signal from this official) - Starting a pull before the starting line flagman has displayed a green flag will be considered a safety violation and will result in disqualification under the general safety and operations rules. U. All finals, or in classes without qualifying rounds, a full pull distance must be set prior to the start of the class. There are no floating finishes in the finals. V. All tracks will have “commitment cones” placed approximately 50’ – 75’ from the start of the track. The puller has until the front of the sled reaches these cones to signal to track officials that they want to come back for their second attempt. Puller must signal to officials by putting one hand in air letting the sled operator and officials know they will be stopping. If the tractor/sled rolls to a stop after the cones that’s acceptable as long as the puller signaled before the front of sled passed cones. - If a puller runs out of bounds before the commitment cones, they have the option to signal for their second attempt and restart the pull. - The puller Cannot continue on with the run after they signal to stop. If puller does make a full pass after signaling, they will be disqualified. W. Extended break in action: An extended break in action is defined as any stoppage lasting 15 minutes or more during an active heat or final. - Finals or Single-Heat Classes: If an extended break of 15 Minutes or more occurs during a final or a single-heat class, the class will be restarted in its entirety. Participants will repull in their original draw order, and first puller procedures will apply. - Heats (no Finalists Clinched): If an extended break of 15 Minutes or more occurs before any tractors have clinched a berth to the finals, the heat will be restarted in its entirety. All tractors will return to the starting line and repull in the original draw order. First puller procedures will apply. - Heats (with finalists clinched): If an extended break of 15 Minutes or more occurs after at least one tractor has clinched a finals berth, the full heat will not be restarted. Tractors already clinched will advance directly to the final. The remaining tractors in the heat, along with the next corresponding positions needed to fill the finals field, will repull in their original draw order to determine the remaining finalists. First puller procedures will not apply, and sled settings must remain unchanged. Example: 18 tractors in a heat, taking the top 6 to the finals. If an extended break occurs after the 15th tractor has hooked, and the top 3 current placeholders have clinched spots in the finals, those 3 advance. The tractors in places 4, 5, and 6 will rehook in their original draw order, along with the 3 remaining tractors in the heat, to determine the final 3 qualifying positions. X. Heat and Finals Standard Format: - 19 or less tractors is Final – (1 time through) - 20-24 tractors – 2 heats – top 5 to the finals - 25-30 tractors – 2 heats – top 6 to the finals - 31-36 tractors – 2 heats – top 7 to the finals - 37-39 tractors – 2 heats – top 8 to the finals - 40-45 tractors – 3 heats – top 6 to the finals - 46-54 tractors – 3 heats – top 7 to the finals - 55-59 tractors – 3 heats – top 8 to the finals - 60-69 tractors – 4 heats – top 6 to the finals - 70-79 tractors – 4 heats – top 7 to the finals - 80+ tractors – 4 heats – top 8 to the finals - Event promotor has the authority to add or subtract the number of finalists before the event starts with the approval by PQS. - If there is a tie for the final transfer spot, all tractors involved in the tie will transfer to the finals. - Event promotor is to choose if Finals order will be determined by manual or electronic draw. Y. Pull Off Procedure: - Any finalists that full pull will keep their tractor at the finish line end of the track to the conclusion of the class. - If there is a tie for 1st, 2nd, or 3rd place in the final round, competitors will have the choice to either pull-off, determine winner by coin flip (or similar means), or split. Choice will be made and communicated to Finish Line Flagger, within 2 minutes of the last finals entrant being unhooked from the sled. If no decision is made in the 2 minute timeframe, prize money and points will automatically be split. Event promotor has the discretion to force a pull off. - If Pull Off is chosen, competitors will pull in the order in which they full pulled. Pull Off will start immediately when sled is set and tractors are pushed back to the starting line. - Ties for any place 4th or beyond will split prize money and points. - Pull Offs are limited to one attempt only. No false start, no dropping position. - Pull Off must be run on the same track, and same sled as the final. If this cannot happen, prize money and points will automatically be split. Z. Weigh In Procedure: All tractors must weigh in and have hitch checked then be staged in a designated area at the starting end of track. Pullers must be sitting on the tractor seat with weight boom extended while checking hitch. Any Adjustments made while in the staging area (adding fuel, air, or hitch adjustment) will require going back over the scales before competing.

Safety

A. YOUR TRACTOR MUST MEET ALL SAFETY AND SHIELDING REQUIREMENTS PRIOR TO HOOKING OTHERWISE YOU WILL NOT BE ALLOWED TO COMPETE AND THERE WILL BE NO REFUND OF ENTRY. B. HELMETS AND FIRESUITS ARE MANDATORY IN ALL CLASSES, MUST BE ZIPPED/SECURED OR WILL RESULT IN DISQUALIFICATION. Fire suits must be a minimum requirement of SFI 3.2A/1. Helmets must be a minimum requirement of Snell 95. C. All tractors are required to have a switch that will kill engine and fuel pump in case of chain/hitch breakage or if sled operator needs to shut down the tractor. A small lite duty zip tie may be placed on the kill switch to ensure it does not accidently get pulled/vibrate loose while going down the track. The switch will be located within six (6”) inches of center of back of tractor with a minimum of a 1.5” circle/loop/ring for the sled to connect to. Spiral loops/key rings are unacceptable. The ring must be substantial enough that when pulled by the sled it will properly activate the kill switch. D. All tractors must be equipped with a dead man throttle. E. All tractors must have a safety device to prevent turnovers. This device is to have wheels or skid plates. Wheels are to be at least 1” wide and 5” in diameter. Skid Plates to have at least 3 square inches at ground contact point. Wheels or skid plates must be no less than 5” (tolerance: -1/4”) behind the rear tires and not more than 5” (tolerance: +1/4”) above the ground. This device must be able to support the weight of the tractor. F. All exhaust must discharge vertically and be securely attached. No more than 10 degrees out of straight upward allowed. G. All drivers must be able to control tractor WITHOUT assistance. Comment: Clutch pedal may be held at starting line while putting tractor in gear, however the driver must release without assistance. H. All single cylinder engines must have a scatter shield on the side opposite the cam. The shield must be made of 1/8-inch steel or 3/16-inch aluminum, covering the full height (bottom of oil pan to top of head) and width of the block. It must be securely attached to the frame or engine block and head, or to a head plate. Refer to Pro V-Twin rules for V-Twin shielding requirements. I. All final drive belts must be covered top 180 degrees and all flywheel and clutch assemblies must be covered 360 degrees with 1/8” steel or 3/16” aluminum and be securely fastened to the frame or engine. J. Engine dampers must meet requirements of SFI spec 18.1 is required. A bolt is required to secure damper to crank. FLYWHEELS AND STARTER PULLEYS must be of billet steel or aluminum (no cast or stamped steel pulleys). No welded on fins. All starter pulleys must have a retaining device to prevent pulley from coming off crankshaft. K. Fenders must extend a minimum of 4” in width and must cover the front of tire to its furthest point forward. It is recommended that the foot step be connected to front of fender to avoid your foot being pulled in by the tire. L. PQS Tech official reserve the right to implement rule changes for the safety and health reasons at any time. M. These safety rules are established by PQS to promote and ensure safe competition across all classes. These safety rules provide a baseline of safety requirements. All safety operations during the pull are the responsibility of the event promoter. Any additional measures to enhance safety are also the promoter’s responsibility and should be communicated with PQS and can be altered to promote a safe event for all pullers.

Chassis

A. Open to two-wheel drive, rubber tired tractors, no dual wheels, chains, or spikes. TIRES MUST BE NO LARGER THAN 26X12X12 FOR ALL TRACTORS. B. All tractors must have at least a 3” seat back on all seats. Seat back must be rigid enough not to flex down excessively when leaned upon. 45 degree angle max. Grab or push bar counts as seat back but must meet height requirement of 3” from top of seat surface to top of bar. C. Drawbar will be horizontal and stationary in all directions. With hitching device at least ½” thick, not more than ¾” in thickness, and must have a 1 ½” width/depth for hook. Pulling point may not be more than ¾” from back edge of hitching device parallel to and not more than 13” above the ground. Drawbar should be made of steel D. No portion of any tractor may exceed 4 feet in width. No portion of any tractor (except stock altered) may exceed 8 feet forward of the center of the rear wheel, including weights. Stock altered is 7 feet forward of the center of the rear wheel. No tolerance on the overall length. E. No weights to extend beyond the back edge of rear tires. F. All tractors must have a hood and grill.

Fuel

A. All tractors in all classes are to run methanol, with no additives. There are two U.S. Federal Grades. Grade A and AA. Either grade is permitted to use. Pullers should ensure that the methanol they purchase meets federal standards of purity. Methanol may be tested at any PQS events by various chemical analyses as considered appropriate by the PQS Fuel Tech Personnel. Deviation from the standards listed below in the fuel sample will result in disqualification. Methanol is a hygroscopic substance and readily absorbs moisture from the air, which rapidly renders methanol illegal as a fuel for use in PQS Pulling. Pullers are cautioned to keep methanol containers tightly sealed at all times to minimize the absorption of water. B. Specification for pure methanol:

• Odor Characteristic
• Platinum-Cobalt scale, mix: 5:5
• Appearance: Colorless-clear
• Carbonizable impurities C. Mechanical Fuel Injection is allowed in Super Stock and 30 Cubes. D. No pressurized fuel tanks E. No Nitrous Oxide. F. Propylene Oxide is prohibited in all classes.

Tear Down and Illegal Vehicles

A. All top money winners will potentially have their engines checked for legality. Teching will include, but is not limited to, the engine. If a class has specific carburetor limitations listed in its class rules, carburetors may also be subject to removal from engine and inspection. Remember, if you do not want the PQS Tech Official to see parts of your engine not involved in the tear-down process, cover them appropriately. Any person who refuses to be inspected for eligibility by routine check of money winners shall not be allowed to enter and/or pull in the class in question until legality is verified. See Rule 1. B. Protest of a competitor's vehicle must be filed in writing to a track official within 15 minutes of conclusion of class. A $250.00 cash protest fee must be submitted at that time. Tear down of protested vehicle must be done by a qualified tech official with the proper testing equipment. Only the tech person and the owner of the protested vehicle are allowed to be present at the time of the tear down. If the vehicle is found to be illegal the protest fee will be returned. If the vehicle is legal the protested vehicle owner will receive the fee. Illegal vehicles will be disqualified for all pertaining classes entered for that event. C. PQS Tech Officials can overrule any misprints in these rules. D. PQS will maintain an Approved OEM Block Design List. Only blocks on this list are permitted. If a competitor wishes to add an OEM block design to the list, the design must first be submitted for review and receive PQS approval before use. Blocks Listed below are approved: - Stock Altered: H&H S/A block, MWSC S/A Block, Kohler K341 Factory Block - Pro V-Twin: Factory OEM Kohler Block - SS/SSC/PS/30CI: Kohler K341 Factory Block, MWSC S/A Block, H&H S/A Block, Jones, J2, Eburg, Woolam/MW, Rabe Block, J2/Julian block

Class Specific Rules

Pro Stock

1. 1050 lbs max
2. 13” Max hitch height
3. 50.5 cubic inch max
4. Single cylinder Pro-Stock is defined as having a one cylinder, air cooled four cycle flat head, two valves same side, commercially produced manufactured cast block engine. Sleeves and welding permitted. Commercially produced manufactured cast block means made by Kohler, Wisconsin, Briggs, Tecumseh and etc. If copy is being made, copied block must meet basic manufactures specs for that engine being copied. Crank and cam location, deck height, two valves same side, valve angle (maximum valve angle of 6 degrees), intake and exhaust port location and factory head gasket bolt pattern.
5. No reverse port engines.
6. The camshaft must be gear-driven directly from the crankshaft, consistent with the traditional engine design for that type. Belt-driven, chain-driven, or other alternative camshaft drive systems are not permitted.
7. A stock appearing in design, Kohler type/Carter boat carburetor must be used if other than stock for the model engine being used. Stand-off pipe or ram tubes are permitted. Choke may be removed. Single Carburetor only. Venturi is not to be larger than 1.200 in diameter and must be round in shape and smooth. Main jet to be on a parallel plane with mounting surface and center of fuel bowl. No slides, no injection, naturally aspirated only. Bowl should remain factory size (2.350) and appearance for Kohler type carburetors. Float, Needle and seat installed and working as intended. Overall length of the carb body is not to exceed 3.50 inches, and 6” in overall length. Top of carb to bottom of bowl max 4”. Max body width (fuel inlet to opposite side) 2.6”. Maximum of 1.8” width in front of carb flange. (The intent of this rule is to maintain a stock appearing carburetor including the fuel bowl. Billet carburetors are permitted as long as they adhere to the specifications noted above. Any other configuration or newly designed carburetor must be submitted to PQS for review and approval prior to use.)
8. Methanol only.
9. Wheelbase 56 inches maximum.
10. Overall length 96 inches maximum.
11. Top placing tractors will be checked for, but not limited to: Fuel, Deck Height, Carburetor, Cubic Inch and Factory Head Gasket Bolt Pattern. in3: 50.500 in.3 zero tolerance. Formula for in.3 is Measured bore x measured bore x measured stroke x .785 = in.3. All bores measured 90 degrees from thrust side. Stock Head bolt pattern, stock head gasket must fit over studs or bolts.

Super Stock

1. 1050 lbs max
2. 13” max hitch height
3. 50.5 cubic inch max
4. Single cylinder Super Stock is defined as any tractor having one cylinder, air cooled four cycle, flat head, two valves same side of engine.
5. No reverse port engines.
6. Intake and exhaust port locations similar to those of a commercially produced block that the engine is based on.
7. If a new block design is created, it must still be based on an OEM block design. All new block designs must be submitted to PQS for approval and accompanied by certification before they can be released or used in competition.
8. PQS will maintain an Approved OEM Block Design List. Only blocks on this list are permitted. If a competitor wishes to add an OEM block design to the list, the design must first be submitted for review and receive PQS approval before use
9. The camshaft must be gear-driven directly from the crankshaft, consistent with the traditional engine design for that type. Belt-driven, chain-driven, or other alternative camshaft drive systems are not permitted.
10. Any type of Naturally Aspirated induction is permitted.
11. Electronic Fuel Injection (EFI) is not permitted.
12. Methanol only. See Rule 5.B
13. Wheelbase 56 inches maximum.
14. Overall length 96 inches maximum.
15. Top placing tractors will be checked for, but not limited to: Fuel and Cubic Inch Limit. 50.500 in3. Zero tolerance. Formula for cubic inch is Measured bore x measured bore x measured stroke x .785 = Cubic Inch All bores measured 90 degrees from thrust side.

Super Stock Carbureted only

1. Same rules as Super Stock but is limited to carbureted engines only

30 Cubic Inch

1. 1000 lbs max
2. 13” max hitch height
3. 30 cubic inch max
4. Single cylinder Super Stock is defined as any tractor having one cylinder, air cooled four cycle, flat head, two valves same side of engine.
5. No reverse port engines.
6. Intake and exhaust port locations similar to those of a commercially produced block that the engine is based on.
7. If a new block design is created, it must still be based on an OEM block design. All new block designs must be submitted to PQS for approval and accompanied by certification before they can be released or used in competition.
8. PQS will maintain an Approved OEM Block Design List. Only blocks on this list are permitted. If a competitor wishes to add an OEM block design to the list, the design must first be submitted for review and receive PQS approval before use
9. The camshaft must be gear-driven directly from the crankshaft, consistent with the traditional engine design for that type. Belt-driven, chain-driven, or other alternative camshaft drive systems are not permitted.
10. Any type of Naturally Aspirated induction is permitted.
11. Electronic Fuel Injection (EFI) is not permitted.
12. Methanol only. See Rule 5.B
13. Wheelbase 56 inches maximum.
14. Overall length 96 inches maximum.
15. Top placing tractors will be checked for, but not limited to: Fuel and Cubic Inch Limit. 30.000 in3. Zero tolerance. Formula for cubic inch is Measured bore x measured bore x measured stroke x .785 = Cubic Inch All bores measured 90 degrees from thrust side.

Pro V-Twin

1. Maximum engine size is 45.5 cubic inches
2. 1050LBS max
3. 13” max hitch height
4. Billet heads are permitted; however, they must retain the traditional OEM port configuration and design for that engine model. Alterations that change the original port orientation (such as converting from side-ported to top-ported designs) are not allowed. Reverse porting is permitted.
5. Engine shielding rules: 1/8" steel or 3/16 aluminum on external side of cylinder extending from head gasket to frame. Shield must be attached to frame at the bottom and to the flywheel shield at the top to make rigid.
6. Wheelbase 56 inches maximum.
7. Overall length 96 inches maximum.
8. Engines: Only OEM-manufactured Kohler V-Twin blocks are permitted in the Pro V-Twin class. Engines must remain factory air-cooled. No other V-Twin engine manufactured blocks will be accepted, and aftermarket or reproduction blocks are not allowed.
9. Front Cover /Timing Cover: The bolt-on front cover (timing cover) on Kohler V-Twin blocks may be replaced with a billet version, provided it follows the same general design and function as the OEM cover. Strengthening of this component and modifications to improve oiling systems are permitted.
10. Carburetor: Limited to one (1) carburetor with one (1) venturi with one (1) throttle butterfly. Maximum venturi size will be 1.200". No air entering after the 1.200" restriction.
11. Steel flywheel mandatory, along with the general flywheel shielding rules of 1/8" steel or 3/16" aluminum 360 degrees.
12. Fuel: Methanol Only

Stock Altered

1. Single cylinder four cycle flathead engines only.
2. Engines must be Kohler, Wisconsin, Tecumseh or Briggs.
3. Engine blocks must have an OEM stock appearance. The current approved blocks are the K-Series Kohler block, H&H S/A block, and the MWSC S/A block. Any new blocks must be submitted to PQS for approval prior to entry.
4. Engines must be factory productions or their OEM replacement with factory deck height.
5. Stock Head bolt pattern = stock head gasket must fit over studs or bolts.
6. Stock Head bolt location and head bolt size.
7. Maximum crankshaft stroke 3.25"
8. Maximum engine bore 3.780"
9. 36.5000 cubic inch limit
10. Maximum engine valve size 1.380”
11. Maximum engine valve lift .330"
12. Billet heads permitted
13. Porting and polishing allowed
14. No external welding or external modifications allowed
15. All thread through finned area is acceptable
16. Welding permitted in crankcase area of the block for repair.
17. Methanol only.
18. Tractors must have garden tractor rear-ends.
19. Tractors must use stock appearing garden tractor frames.
20. The front of the engine block can not exceed 52 inches from center of the rear axle. Front pulley and crank are allowed to exceed 52”.
21. No front suspension systems, including air bags, are allowed.
22. Front axles must remain rigid with no form of suspension.
23. Weight Class 1050 lbs.
24. 13” Max hitch height
25. A stock appearing in design, Kohler type/Carter boat carburetor must be used if other than stock for the model engine being used. Stand-off pipe or ram tubes are permitted. Choke may be removed. Single Carburetor only. Venturi is not to be larger than 1.000 in diameter and must be round in shape and smooth. Main jet to be on a parallel plane with mounting surface and center of fuel bowl. No slides, no injection, naturally aspirated only. Bowl should remain factory size (2.350) and appearance for Kohler type carburetors. Float, Needle and seat installed and working as intended. Overall length of the carb body is not to exceed 3.50 inches, and 6” in overall length. Top of carb to bottom of bowl max 4”. Max body width (fuel inlet to opposite side) 2.6”. Maximum of 1.8” width in front of carb flange. Velocity stack/intake horn must be a separate piece from the body of the carburetor. (The intent of this rule is to maintain a stock appearing carburetor including the fuel bowl. Billet carburetors are NOT PERMITTED. Any other configuration or newly designed carburetor must be submitted to PQS for review and approval prior to use.)
26. Wheelbase: 52 inches maximum
27. Top placing tractors will be checked for, but not limited to: Fuel, Bore, Stroke, Carb Size, Valve Lift & Valve Size and deck height. Cubic Inch: 36.500 Cu. In. No Tolerance. Formula for CU. IN. is Measured bore x measured bore x measured stroke x .785 = Cu. In. All bores measured 90 degrees from thrust side.
28. If running a factory Kohler produced block the maximum size bore will be 3.830" with a maximum cubic inch of 37.500.

Stock Altered RULE CLARIFICATION: We are asked many times what can and cannot be done to the outside of the engine in the port area. Below we have defined what we will allow and disallow. Any intake port that's been braced or repaired ONLY, will be checked for stock carb mounting stud locations, center to center distance, height, and port location. See the diagram in the original PDF.