A head assembly for an internal combustion engine includes an electromagnetic valve actuation system. The head has an intake or exhaust passage defined therein. A valve is disposed in the passage and is operable to selectively open and close the passage. The head has a cooling passage defined therein for passage of a cooling fluid. An electromagnetic actuator has a piston in mechanical communication with the valve and a coil in fluid communication with the cooling passage. The electromagnetic actuator is operable to move the valve between a closed and an open position.

A valve timing control device of internal combustion engine comprises a chain case 6 that is fixed to a cylinder head 101 of the engine and has a circular opening 55 for receiving therein a cylindrical housing 5a of an electric motor 8, an annular seal member 58 that is operatively received in an annular clearance defined between an outer cylindrical wall of the cylindrical housing 5a and an inner cylindrical wall of the circular opening 55, and a cover member 4 that is connected to the chain case 6 to cover the circular opening thereby concealing the annular seal member from the outside, wherein when the cover member 4 is removed from the chain case 6, the annular seal member 58 becomes exposed to the outside through the circular opening 55 of the chain case 6 for a visual inspection of the annular seal member.