High compression. Oil line installation kit required. No fuel system or ignition systems included. Special head machining fits stock length intake manifolds (S&S manifold size 410). Stock style breathing system; compatible with stock and most performance air cleaners. Includes Super Stock™ heads, crankcase, high flow oil pump, cam cover, and easy start 640 gear drive cams. Made in the USA. Cylinder heads on this engine are specially machined to compensate for the non-stock cylinder length. As a result, it is compatible with the manifold and the throttle body with stock length intake runners. In addition, the breather vent bolt location has been adjusted so it is in the stock location, so stock style air cleaner back plates will bolt up to this engine..