Designed for more power. Stiffer and stronger than original, increased material permits porting for improved airflow. Features the same outward appearance as the original 1966-1971 heads, except for shape of alternator boss. All components attach the same as original (intake and exhaust valves, valve guides, seats, rocker gear, etc.). Features 170 cc combustion chamber and 2.25" intake and 1.94" exhaust valve machining.