Need advice!!! My 1980 4x4 pickup has, I believe a hybrid 20/22R - and a noisy rocker has recently gotten worse - it now sounds like a little fella its a machine gun hiding under the rocker cover. From 0.008 (Int) and 0.012 (Ex) gapped down to 0.006/010 cold. This just made to worse, louder with a very real metal on metal ringing noise. I haven't removed the cam/valve train from the head yet. But on closer inspection, the valve adjustment screws are all in good shape with no pitting and the little polished hourglass shape is plainly clear on the valve stem end. The cam followers and valve screws are all nicely lined up. The cam lobes are all discolored (burnt?). Oddly the TDC mark on the cam sprocket is about 1/2 a link off - not sure what that means. So all you 20/20R geeks - do I renew the lot, change the cam, what? I REALLY need the help!