An internal combustion engine having a valve lifter assembly is disclosed. The internal combustion engine comprising an engine head having at least two wells adapted to receive at least one valve lifter, the at least one valve lifter includes a flat surface, at least one spacer installed within the engine head having a first surface, a hollow portion, and a second surface, the first surface is tapered with respect to a vertical axis of the at least one spacer, and a tie-bar plate for coupling the at least one spacer using head bolts. The at least one spacer and the at least one valve lifter are operatively arranged during operation in such a way that the flat surface of the at least one valve lifter faces the first surface of the at least one spacer to prevent rotation of the at least one valve lifter.