Product Information Hydraulic Roller - 4-Pattern: Recommended in larger c.i. and high compression applications. 3500+ stall.; Outboard Specs: 307/319 Advertised Duration, 255/265 Duration .050", .638"/.622" Lift, 108.5 Lobe Separation; Inboard Specs: 305/317 Advertised Duration, 253/263 Duration .050", .638"/.622" Lift, 107.5 Lobe Separation; 3300 to 7500 RPM range; Recommended use with 1.6 rocker arm ratio