Leaking Valve covers!

[72superBB]

Anyone have any suggestions on how to stop leaking valve covers?

I have used rubber and cork. The bolts seems to always be loose. I thought I had them tight enough. I am getting oil collecting in the pocket of the heads and the header gasket. THe picture shows how they are bolted on now. I have not used a torque wrench to get the correct pressure, but they were not tight and not even loose when I was done. I have cleaned the cover up since this pic was taken, so it is not from the grommit area that looks dirty.

thanks

Thanks for your input.

Ron