Von is correct that our current line of valve cover gaskets are not designed for OEM cylinder head surfaces. Only aftermarket heads that have been machined flat & true on the valve cover rail.
With that said..... our mopars are at a real disadvantage when it comes to sealing the valve cover because of how bad the casting is on the gasket rail of the cylinder head. Not to mention the close proximity of the exhaust manifold and the high heat generated from it so close to the gasket.
I recently spoke with an engine builder who had to remove .070" off the valve cover rail of the head just to get a flat surface
I'll assume not all heads need this large amount removed and sure some need minimal amounts of material removed.
The issue with cork & rubber gaskets is they take a set (compression set) and need constant re-torquing to maintain a load on the fastener.
Von if you have the heads off you can have the gasket rail milled flat. This will be an advantage with ANY gasket you may use.
I'm in the process of evaluating new materials to address this common problem and will be testing samples soon on my Charger. Once I have some initial testing done I may put some out in the field for testing to get a review of others results
