9. Lashing the valves isn’t as tedious a process as you might think. For hydraulic roller setups like this 396, each poly lock requires a zero lash. This means tightening the poly lock down with a 5/8-inch open wrench until the pushrod stops spinning in the rocker arm pocket. Then, preloading the lifter requires an additional 1/4 to 1/2 turn. Next, throw on the valve coverswe’re done!