Proper Engine Valvetrain Alignment

The correct lifter bore alignment is normally found with a B-H-J fixture, which works in much the same manner as the one that centers the cylinder bores. If a lifter bore is out of alignment, many engine builders can ream it out, insert a bushing, and then re-cut the lifter bore in the correct location. This can help in a couple of areas. First, an improved alignment between the lifter and the cam lobes helps ensure that both wear properly, which is a concern with the high spring rates being used today. Second, when a cam is designed, it is assumed that the lifters are in the correct locations. If they are off by a degree or two, they will contact the camshaft at a different point from where the designer intended and make the valve opening and closing events happen either earlier or later than intended. This, of course, is going to cost you power.

This actually involves two steps-properly locating the cam bores and the lifter bores-but they work hand-in-hand. Earlier, we mentioned boring and honing the cam tunnel, which is done to ensure the bores are the correct size and in alignment with each other. Valvetrain alignment takes it a step further by ensuring that the camshaft centerline is the correct distance from the crank centerline. This can be off slightly on mass-produced blocks and can affect cam timing.

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