Free Adjustment Guide Chevrolet Valve Lash

Free Adjustment Guide Chevrolet Valve Lash

Without the use of hydraulic lifters (mechanical lifters), the valve train must be adjusted with a certain amount of “slop” in it (“lash”). This lash is necessary, since the various components in the valve train tend to “grow” and expand as they heat up from normal engine operation. As the components “grow,” they take up a large portion of the lash, but some lash must still be retained as a safety margin. If there were no lash, there would be a risk of the valves not closing fully, resulting in poor engine performance and burnt valves.

This lash, however, results in a bit of valve train noise as parts “clank” together, and this clanking induces wear of the valvetrain components. When the hydraulic lifter is at the “low” point in its bore (the valve is closed), the body of the lifter is exposed to pressurized oil in the lifter oil galley. The lifter body has a little hole in it, and this hole allows oil to enter and/or exit the lifter body. The pressurized oil in the galley thus enters the body of the lifter, and pushes lightly on a plunger in the roof of the lifter body. This plunger is about a half inch in diameter, giving it a total area of approximately 0.12 square inches.