S&S Cycle 74" Top End Kit For Harley Shovelhead 1966-1978

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Fitment Notes & Exceptions

• 74" engines have a stroke of 3-31/32" and 80" engines have a 4-1/4" stroke but the cylinder length for both engines is the same. The 74" piston is taller than the 80" piston, which results in the same piston-to-head clearance for both engines. While it is possible to install an 80" top end on a 74" engine, this will result in very low compression and poor performance. A 74" top end will bolt to an 80" crankcase but the pistons will contact the cylinder head due to the combination of the taller 74" pistons and the longer stroke of the 80" flywheels. Therefore, it is important to correctly identify the stroke of the engine before ordering a top end kit.