Single Engine Modified

 *** WILL FOLLOW ALL NORTHWEST MODIFIED RULES WITH THE FOLLOWING EXCEPTIONS: 

1. Weight Class: - 6200 and 7200 lbs. classes. 


2. Engine Limit: 

a. Automotive -type cast iron block. 

b. Cast iron or aluminum heads. One (1) spark plug per cylinder. Two (2) valves per cylinder. 

c. Eight (8) cylinder maximum. 

d. Any intakes allowed. 

e. Two (2) four-barrel carburetors maximum or fuel injection. Naturally aspirated; no blowers. 

f. 540 cubic inch. 

g. Spark plug shielding - must cover the plugs to deflect plugs with a minimum of .060 metals. 


3. Transmissions/Clutches. Clutches must meet minimum SFI Spec 1.1 or 1.2. Bell housing must meet minimum SFA Spec 6.1. Automatics must run a minimum SFI Spec. 4.1 blanket that extends from back of engine block to front of tail shaft. Blanket must have a minimum 6”overlap and must be tight to back of block. 


4. Any Single Engine Modified Tractor with a hood must have a firewall in place. 


5. Fuel: Gasoline or alcohol. No oxygen accelerators. 


6. Driver’s Safety a. Fire suit, leather boots, helmet and fire proof gloves are required. b. Head socks highly recommended. c. Roll bars required. 


7. All tractors not pre-pumped and sealed will be pumped at the completion of every event.  All competitors may be required at registration, to sign a transmission and clutch certificate waiver stating the competition vehicle meets all safety requirements 


*** Only class specific vehicles are permitted to compete in this class. No farm, antique, or other modified tractors are permitted.*** Any driver arguing with a track official is subject to immediate disqualification. All decisions of the track official will be final at each pull. Any protests will be settled at next club meeting.  All rules to be interpreted by officials. Any unforeseen problems or oversights will be ruled on by officials on sight. All general and safety rules apply. All rulings will be final. Officials reserve the right to allow or disallow a competition vehicle to compete on the basis of any safety concern or infraction.  


Northwest Modified Tractor WILL FOLLOW ALL NTPA SAFETY RULES 


1. Modified tractors are those using any combination of engine(s), transmission(s), and final drive. 


2. No portion of tractor may exceed 14’ forward of the center of the rear wheel. 


3. Chassis – Modified tractors that have the frame bolted to the transmission shall also have the frame bolted to the axle housing to prevent splitting of tractor. The frame must be of sufficient strength that even when the bolts from the plate of the transmission or rear end are removed, the frame still supports the weight of the tractor in the heaviest class being entered. 


4. Driveline/Driveline shielding: a. No shaft over 48” long allowed. No input or output shaft that attaches to drive shaft may extend more than 4’ beyond a bearing. b. A minimum of 1” material between bolt and end of drive shaft shield. A minimum of 1” material to be in pilot holder at each end of the drive shaft shield. A minimum of eight (8) 3/8” (grade #8) bolts to hold carrier-bearing assembly if attached to a vertical plate. 


5. Tires: a. Tires no more than 30.5” wide. b. Rim diameter limited to 32” on tire widths over 24.5””. Note: Width determined by manufacturer size. 


6. Engine Limit: 

a. Naturally aspirated automotive engines (must be carbureted) up to three engines, not to exceed 2000 cubic inches collectively. 

b. No more than two (2) pressurized automotive engines (blowers, turbos, or fuel injected) No cubic inch limit. 

c. Turbine limit – 1 at 2300 H.P.; 2 at 1300 H.P. government rating. 

d. Other – Truck, aircraft (diesel or Allison) pressurized limit one 

(1). 7. Modified Open Class: Northwest rules for Modified tractors apply. Pro-Stock, Super Stock, Mod-Stock can enter but must meet Northwest rules. 


8. Any driver arguing with a track official is subject to immediate disqualification. All decisions of the track official will be final at each pull. Any protests will be settled at next club meeting. 


9. All rules to be interpreted by officials. Any unforeseen problems or oversights will be ruled on by officials on sight. All general and safety rules apply. All rulings will be final. Officials reserve the right to allow or disallow a competition vehicle to compete on the basis of any safety concern or infraction. 

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