An apparatus for assembling an overhead camshaft that comprises a hollow outer shaft having at least one slot formed, an inner shaft having at least one pin hole formed, at least one first cam lobe, and at least one second cam lobe. The apparatus comprises a first fixture having two journals, on which the outer shaft is disposed, formed at opposite ends thereof. A second fixture has a plurality of journals on which at least two of the at least one first cam lobe and the at least one second cam lobe are disposed. A third fixture restricts upward and downward and rotational movements of at least one of the outer shaft, the at least one first cam lobe, and the at least one second cam lobe.