Original Evolution engines have automatic valve lash adjustment, just like Shovelheads and Panheads. Unless they have been removed by the previous owner, all these engines have hydraulic units that eliminate valve lash as soon as oil pressure is applied. The Evolution also no longer has a basic setting like the Panhead or Shovelhead engines. The pushrods have a fixed length, the preload of the hydraulic units is determined when the pushrods are installed.