On a hydraulic roller 351W I want to determine proper push rod length and piston to valve clearance. I was thinking about using checking springs but I'm concerned the force required to compress the clay could be sufficient to compress the spring in the lifter resulting in an inaccurate measurement. I could eliminate this possibility if I pumped up a couple of lifters for the test. I've read a lot of differing opinions on potential problems that could arise when starting a new engine with pumped up lifters so I'd like to avoid that. I could just use a dial indicator but I'd like to determine radial clearance between the piston and valve at the same time. If I did pump up a couple of lifters is it worth bothering with the checking springs or should I just go with the actual springs? I realize I can't use the dial indicator if I use the actual springs. Also, I don't have any old lifters to modify for this.