Unfortunately my bad luck, exactly the one's I have recently used on my BB Edy aluminum head, MOPAR performance aluminum valve covers.

Both sides at rear bottom bolt seep no manner how tightly I cinch them and how often. It does seem that I can always get another half turn of the bolts as it appears this gasket has infinite crush capabilities.

Had switched from cork for re-usuability which had only leaked a very modest amount on right rear cover,,,which was corrected with a dab of silicone black at that point.

Moroso's, I have never removed but about to give them the silicone treatment,,,,but am uncertain if will do any good as they are now oil soaked.

If this fails, back to cork I go. Yes I suspect that valve cover machining may be questionable too and in that is where my Moroso problems lie. Particularly as others are having success.