A cylinder head and valve train mechanism for an internal combustion engine having six valves per cylinder. There are provided four intake valves and two exhaust valves. In some embodiments, the size of the intake valves is varied because they are served by a common port so as to insure equal flow to the cylinder through all valves. In one embodiment, a single insert forms two of the valve seats. Also, two of the four valves are disposed at acute angles to both a plane containing the cylinder bore axis and a perpendicular plane passing through this axis in many embodiments. In these embodiments, the cam lobes that operate the angularly disposed valves have cam surfaces that are inclined relative to the axis of rotation of the camshaft. In some embodiments, all of the intake valves are operated by a single camshaft. In other embodiments, two camshafts operate different pairs of the intake valves. Various bearing arrangements for the camshafts are illustrated and described.