This starter shim is 3/8 inch thick 6061 lightweight aluminum and the starter cam bushing is zinc coated steel. To install the starter cam bushing a 9/16 hole must be drilled into the bottom starter hole. Rotation of the cam bushing allows ring gear end gap to be set correctly to prevent starter and flywheel damage. Not to be used with Stock Starters. A MUST FOR HIGH COMPRESSION ENGINES
