John,

I'm going through a simular noise issue with my 68 solid lifter hemi. I pulled the valve covers and went through the lifter adjust procedure only to find that they were pretty close to being correct. In the process of cleaning up the valve covers for new gaskets I noticed that the drivers side (the side that had the noise) valve cover had very slight cut marks on the covers made from two of the valve retainers. I decided to make some small dimples in the side of the covers to see if that would make any difference...motor sounds much better now - like a sewing machine on steroids...

Good luck, I hope you find the cause.

Jim
68 Hemi Road Runner