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Clone Limited – Age 15 years & up – 375 lbs. Methanol allowed for fuel. Approved Engines: Box Stock Project, Harbor Freight, Homier. Any style clutch allowed. Maxxis tires only, any compound allowed.
Block Requirements: Stock engine block as produced with no alterations or modifications other than what is specified here. Blocks may be welded for repairs as long as the repair does not constitute a functional modification to the block or the blocks function. No welding to block from cooling fins up. Governor stub hole may be tapped and plugged or siliconed. All bolt bosses in block must be stock size but may be Heli-coiled. Bore and Stroke: Stock bore is 2.768” and may be over bored to 2.718” (approximately .040” overbore). Stroke is 2.123” +/-.005”. Stock sheet metal components must be in place and secured. Blower housing must remain stock. Pull start is mandatory. Any size fastener is allowed to secure sheet metal.
Gaskets: Gaskets are a non-tech item. Maximum amount of side cover gaskets is 3. Maximum amount of head gaskets is 1. Minimum thickness on head gasket.
Piston Requirements: Piston can be stock or after market. Any OEM or after market or standard size pistons may be used including Honda. Over sized rings are allowed. Rings to be checked against know stock parts. Ring gap is a non-tech item.
Camshaft Requirements: After market cams are allowed but must not be over .308” lift at the valve. Stock cam core is mandatory. No grinding or lightning allowed on stock cam core. Stock cam core will be checked against sample stock cam.
Connecting Rod: After market aluminum rod of stock length allowed.
Crankshaft Requirements: Stock unaltered factory crankshaft only. Factory unaltered timing gear only. Timing gear must remain in factory location. No modifications to crankshaft allowed. Crankshaft Journal diameter is 1.180”, 1.175” minimum. Stock factory stroke +/- .010 is allowed.
Valve cover: Stock unaltered valve cover is mandatory. Valve cover will be compared to know stock part. Only alteration is pulse fitting for fuel pump.
Cylinder Head Requirements: Stock unaltered cylinder head only. Machining of gasket surface allowed. Porting allowed. Valve seats must remain stock and cannot be modified in anyway except for valve seal. Valve seats 45° only. Any style head bolts are allowed as long as stock size is maintained. Minimum head gasket thickness is .007”. Push rod guides and plate must remain stock. Push rods must remain stock and stock length. Head specs: Minimum depth from gasket mounting surface to top of combustion chamber surface .300. Minimum depth from gasket mounting surface to top of valve seat .280. Porting allowed. Intake valve seat Specs: Maximum inside diameter of .894. Exhaust seat Specs: Maximum inside diameter of .855. If lip of valve seat is not visible for checking depth, head is illegal.
Valve Train: Valve train must remain stock. Rockers, ball adjusters, rocker arm studs, lock nuts, pushrods and lifters must be stock and unaltered. Max lift at valve check will be enforced. Stock unaltered valves only. Valves must be one angle only, 45°. No polishing or lightening of valves. Valves may be reground but no knife edging of valves is allowed. Valve springs are not subject to tech. Any size valve lash allowed. Valve Specs: Intake valve minimum head diameter .977. Intake valve minimum length 2.499. Exhaust valve minimum head diameter .936. Exhaust valve minimum length 2.450. Minimum valve stem diameter on both valves is .210. Valve Guides: stock valve guides or after market valve guides are allowed. Lifter bore guides are also allowed.
Flywheel: ARC #6619 #6618 billet flywheel with cooling fins only. No machining or alteration of any kind allowed to flywheels. Flywheels will be checked to known stock part. Minimum weight for flywheel is 3.3 lbs. Timing key is not a tech item and can be removed.
Carburetor: Stock 348 E Tillotson carb is mandatory. No modifications allowed to carb bore and throttle shaft, butterfly or screw. Any filter adapter allowed except for off set adapters. Any after market Air Filter allowed. Return spring on throttle mandatory.
Intake Manifold: Any after market intake manifold is allowed as long as it isnot over 2”. Maximum bore diamter is .845. Fuel pump can be pulsed from the intake manifold.
Fuel Tank: Stock fuel tank must be removed. Floor pan mounted fuel tank is mandatory. After market fuel pump of any kind is allowed. Fuel line pulse hose length can be no longer than 14”.
Ignition system: Stock ignition system only. No modifications of any type allowed. Subject to known stock part on shape, looks, voltage and ohms. Sparkplug connector is a non-tech item. Spark plug is a non tech item.
Header and Muffler Requirements: Any header allowed. Header may be bent in any shape to keep it away from the driver. Muffler must not extend past rear bumper. Header must be securely wrapped. Header must be wired from one bolt to the other. Header straps are mandatory.
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