Stock cam 360 idles bad, dies in gear, fixed!

Can't say that I have had a lot of experience playing with preload on hydraulic lifters but but back in my younger days working on SBC engines I never noticed an change in the idle quality or manifold vacuum level with a change in preload and most recently on the magnum headed 360 I am running I went from 0.025 to 0.055 preload on the lifters and didn't see any change in the idle quality or manifold vacuum. If there was a change in power it wasn't enough for me to notice.

I have experienced lifter pump up at high rpms from too much preload but that is not the issue being discussed.