Some Twin Cam heads using 7.0mm valves may crack in the port end of the valve guide boss. These valves have .005" oversize stems to re-establish the correct valve stem to valve guide clearance if the head has cracked. Valve guides must be reamed/honed to set correct clearance, the a valve job performed to ensure proper sealing. Oversize portion of the valve stem does not extend into the keeper groove area; OEM valve keepers can be used.
