Start of fuel delivery for a fuel-injected engine having separate unit injectors is adjusted by effecting a positional adjustment of camshaft lobes on a camshaft. The camshaft is used to operate the unit injectors, as well as control exhaust valve operations. By separately controlling the position of the cam lobes which operate the unit fuel injectors, a change it start of fuel delivery is effected. A change in relative position of the cam lobes is accomplished by shifting a guide rod within a hollow body of the camshaft. The change in position of the guide rod, in turn, effects a change in position of the cam lobes which are connected to the guide rod.