Valve operating system in internal combustion engine

In a valve operating system for a multicylinder overhead cam type internal combustion engine having

• first, second and third intake-side cams and first and second exhaust-side cams all provided on a single cam shaft positioned above at least one cylinder,
• first and second intake-side rocker arms operatively connected independently to a pair of intake valves for the cylinder and a third intake-side rocker arm disposed between the first and second intake-side rocker arms, which arms are swingably carried on an intake-side rocker shaft for engagement with said first, second and third intake-side cams, respectively,
• first and second exhaust-side rocker arms operatively connected independently to a pair of exhaust valves for the cylinder and swingably carried on an exhaust-side rocker shaft for engagement with said first and second exhaust-side cams, respectively,
• a connection switchover mechanism provided on the intake-side rocker arms and capable of switching-over the connection and disconnection of the adjacent intake-side rocker arms,
• said first to third intake-side cams are provided adjacent one another in an axial direction on said cam shaft, said first, second and third intake-side rocker arms are disposed between said first and second exhaust-side rocker arms, and
• at least two of said first, second and third intake-side rocker arms, as well as said first and second exhaust-side rocker arms are provided with rollers for rolling contact with the corresponding cams, and improvement comprising,
• said first and second exhaust-side rocker arms being provided with axial notches reducing their width in the axial direction of the camshaft near the camshaft for accommodating portions of said first and second intake-side rocker arms, respectively, near the camshaft and reducing the overall width of the combined rocker arms in said axial direction.