Yeah, I hear that, but it doesn't take much for them to be too tight, you could try pulling the valve cover's and loosening them all up just a litlle and see if there is a change. People do this various different way's, but I will explain the way I do it, of course I am sure you followed what the book said about doing the first half off the valve's on TDC #1, and the other half 1 revolution around on TDC #6 and then do the other half, I hold the pushrod between my index finger and my thumb and rotate the pushrod as I tightening the nut down, just as soon as the pushrod has no up and down movement but it should still turn between your fingers with a slight drag tighten the nut 1/2 aturn more to preload the lifter and that's it.