Lunati offers super strong, heat treated, machined steel valve spring retainers and spring locators plus super lightweight titanium alloy retainers for Harley-Davidson® Evolution Big-Twin® and Twin-Cam Evolution® V-twin engines plus “Evo clone” engines found in aftermarket bikes. Lunati steel retainers are made from premium quality, 4140 steel alloy bar stock, precision machined on high-speed, automated lathes. They are then heat treat hardened to exact metallurgical standards for hardness and depth penetration, to increase strength and wear prevention. After heat treating and inspection they are black oxide coated, to prevent corrosion. For serious performance bike engines, or all-out race engines, Lunati also offers precision machined, titanium alloy spring retainers. These ultra-light, super strong retainers are made from premium 6AL4V titanium alloy, precision machined and dimensionally inspected. Lunati titanium retainers offer superior strength and amazing lightness. Both are available for Harley-Davidson® Evolution Big-Twin® and Twin-Cam Evolution® V-twin engines plus “Evo clone” engines found in aftermarket bikes. Lunati steel and titanium retainers can also be obtained in complete Valve Spring Kits. Contact Lunati’s tech staff for the specific application for your Harley-Davidson® or Evo-clone big-twin engine.