Cylinder head and internal combustion engine having the same

An internal combustion engine comprising:

• a camshaft configured and arranged to rotate in accordance with a rotation of a crankshaft;
• a cam coupled to the camshaft to rotate in accordance with the rotation of the camshaft;
• a valve lifter operatively coupled to the cam such that the valve lifter is periodically pushed down by the cam as the cam rotates;
• and
• a cylinder head rotatably supporting the camshaft and the cam, the cylinder head including
• a lifter guide boss part defining a lifter bore that slidably supports the valve lifter,
• a concave relief groove portion having a predetermined width and a predetermined depth formed on the lifter guide boss part in a position corresponding to a rotation direction of the cam to avoid an interference between the cam and the lifter guide boss part due to a rotation of the cam, the relief groove portion including a pair of groove side surfaces and a groove bottom surface with a pair of corner sections being formed between the groove bottom surface and the groove side surfaces, and
• a guide portion protruding from the groove bottom surface of the relief groove portion in a sliding direction of the valve lifter to slidably guide the valve lifter, the guide portion being spaced apart from the corner sections of the relief groove portion.