The disclosure relates to fuel pump housings and fuel pump systems incorporating the same. The fuel pump housing includes at least one tappet housing portion configured to receive at least one tappet assembly and a main bore portion fluidly coupled with the at least one tappet housing portion such that the main bore receives a camshaft. The main bore includes an uncut portion and at least one relief cut portion proximal to the at least one tappet housing portion. The uncut portion defines a first centerline, and the relief cut portion defines a second centerline offset from the first centerline.