Sidewinder® .650″ Valve Spring Kits for Twin Cam 88® big twins w/ stock heads (both 7mm and 5/16” valve stems) and all S&S Super Stock® heads (5/16” valve stems). Works well with cams up to .650″ lift. Manufactured from ultra clean high silicon Kobe alloy wire then micro shot peened and nitrided. CNC machined 9˚ locks. High performance conical single wire spring. Chromoly forged retainers. Kit contains: Valve keepers, Top & Bottom collars, Springs, Shims.