What is the best valve cover material?

[Henrius]

These darn old V-8 engines (mine a 383) are always leaking oil. Most common place is out the valve covers. My valve cover gaskets were replaced not to long ago with cork gaskets. Do rubber gaskets seal appreciably better?

 

[AL_Brad]

I've always used the Felpro FEL-1612 (or the 50145) rubber coated fiber. Never had leaks - just don't over tighten.