The S&S 560S cam is for 1948-1969 Harley-Davidson big twin models with 88 to 103 inch engines between 9:1 to 10:1 CR - excellent power across the rpm range. 3,500 - 6,000 rpm. Not recommended for stock displacement or lower compression engines. High lift valve springs and normal clearance checks required. Solid lifters or aftermarket hydraulic tappets recommended. S&S Part #: 33-5059