In an effort to perfect Milwaukee-Eight« engine valve train geometry, while improving durability, JIMS« has developed performance rocker shafts and proprietary hardware The rocker arm shafts are precision machined from a low alloy nickel, chromium, molybdenum case hardened steel. The hardware flats on the end of the shafts are held to a .0005ö parallel tolerance, assuring the rocker is seated in the correct position with the pushrod cup & valve stem tip when installed correctly. SHAFT ROCKER ARM KT M8