Speedmaster Stainless Rocker Arm Issues

What am I doing wrong??? Got new H&S full roller arms. I have already reduced the thickness of the shims from the ones supplied by H&S to about half the size. I had a solid .015-.020 clearance. But when I tighten the rocker shaft down with the push rods installed every thing tightens up and I lose the clearance. I tried positioning the hold down blocks. It worked great. It has the proper clearance but tighten it down with the push rods installed it all goes tight. These are on Eddy RPM heads.