The COMP Cams ID locator spring seat replaces older shims with a thin, hardened steel alloy seat that both protects the head and shim and locates the spring using an inboard locating shoulder. That shoulder centers the seat and secures the spring while avoiding the extensive head machining cups once required. The 4777 size lists a 1.540" OD and .640" ID for compatible dual-spring applications.
COMP Cams ID Spring Seats 1.55 X 630 X