Every fraction of a second, the cam lobe comes around and slaps the valve open, which means that it's impossible to get a true "zero lash" starting point on a running engine. The lifter is going to be operating in a partially-compressed situation all the time, plus it's going to be virtually impossible to get a true adjustment with the lifter moving. Compressing the lifter while it's stopped on the base circle of the cam lobe, and measuring the exact amount of bleed-down between the lifter body and the plunger is the only accurate way to get an adjustment, but a stopped-engine adjustment without waiting for the lifter to bleed down is usually suitable for street use. I'm accustomed to adjusting race engine hydraulic lifters that operate in the 7,000+ RPM range, and a running adjustment is definitely out of the question in that case.
Jerry
Last edited by Hotrod Lincoln; 12/27/2007 9:31 PM.
