You'll need to do some measuring of the travel of the lifter plunger to determine how far you need to set the preload. Start with a lifter out of the engine, and measure the distance from the top of the lifter body to the cup-shaped pushrod seat with something like the depth gauge end of a dial caliper. Record the measurement. Then compress the plunger to the bottom of its travel by gently squeezing it in a vise with a bolt or some other type of extension piece bearing against the plunger and measure again. The difference in the measurements is the total travel of the plunger. The preload on the lifter needs to put the plunger at the approximate midpoint of its travel. You'll need to figure how many turns of the adjusting screw will be required to accomplish this and adjust accordingly. Fortunately, most lifters will give you a little wiggle room, maybe half a turn +/- of the adjuster from the sweet spot. Good luck!
Jerry
