Adjusting Roller Lifter Valve Lash Big Block Chevy

There are a couple of ways to adjust valves on engines that have solid or roller lifters. The first way is to bump the engine over preferably with a remote starter switch so you can be under the hood watching the movement of the valvetrain. The idea is to SET THE INTAKE VALVE LASH when the exhaust valve just starts to open. SET THE EXHAUST VALVE LASH when the intake valve is MID-WAY to closing. That's it!

This is the simplest and fastest way for the beginner. There are even faster ways by doing multiple cylinders at a time but I won't go into that right now.You also need to understand that cams are not perfect, and although lobe base circles should not have any runout, they often do. Not only that but some cams can have relatively long tappet ramps which can cause problems when setting the lash as I stated above. If you really want a perfect setting you need to make sure the lifter is positioned perfectly on the base circle before any adjustments are made.

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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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