I'm switching to cork gaskets on my 440 with stock heads and stock stamped steel valve covers. Silicone kept loosening up, right up to the point where they popped out altogether.

Based on what I've read here, I'm thinking of using RTV between the new cork gaskets and covers, and a thin film of grease of some sort between the gasket and the head, probably Sil Glide. Would most of you agree this is the way to go?

After3styles of gaskets tried with numerous methods I have found to make sure the cover fits flat and even with the edges of the head. Then I use cork gaskets with the retaining tabs. I then put indian head gasket shellac on the valve cover to keep it from moving and causing leaks. A little grease on the head flange, and don't overtighten.My problem was the gasket kept slipping off of the head flange a fter a while and causing a leak

yup, i use permatex ultra copper to seal the gasket to the vc and good ol' white grease between the head and gasket. then you can re-use the gasket many times.

I use the black ultra permatex to the valve cover. The key as stated is not to overtighten.

I don't know what I could have done with the silicone gaskets. Maybe it's just too smooth with stamped steel covers, and the silicone gasket is too tall. I tightened them up a couple times after heat cycles, they were always loose and leaking anyway, and apparently the multiple tightenings cause them to walk right out. Fel-Pro cork, here I come...