I ain't used em (yet). SCE with their dead soft copper gaskets, not these felpro shims, wanted me to use Indian Head cement in the shoe polish type brown bottle but ideally to O ring the block on their items. On these it says on the pkg to use a felpro blue gasket on one side which I dont quite get. they are .020" & iirc the ad says .030" EDIT I think I would get some thicker gaskets, even some Cometics if need be for the right thickness.