EngValve Spring Seat, ID Locators 1.50" OD .570" ID .060 Thick, ID Spring Locator Set of 16 - 1.500" OD, .570" ID, .060" Thickness, None, Made from hardened steel, these locators use an inboard locating shoulder to center the seat and hold the spring in place. The 4783 features a 1.540" OD and a .640" ID., Engine Valve Spring Seat.