A valve cover assembly for sealed engagement with a cylinder block includes a cover portion, a rail and a molded-in-place elastomeric bridge molded to the cover portion and the rail maintaining the cover portion and the rail in spaced relation to one another. The rail has an outwardly extending mounting flange providing a hard mounting bottom surface that is coplanar with the rail sealing surface. A seal depends from the sealing surface of the rail when in an uninstalled, uncompressed state for compression against the cylinder block upon the sealing surface and the hard mounting bottom surface being brought into engagement with the cylinder block, thereby establishing fluid-tight seal between the valve cover assembly and the cylinder block.