Valve train noise

Preload is measure by the position of the lifter piston position. While the lifter is at the bottom of the lobe the piston should be at half its travel down maximum when empty. For example If the travel is 1/4 the preload should be 1/8 maximum. Those numbers may not be accurate they are just an example of where to set the preload. no matter the full travel divide it by 2. Less is OK but never go more or the piston may close off the feed hole and the lifters may never fill with oil if they collapse a bit.