My solution was to purchased one of the vintage C.A.W. cast aluminum valve covers and a vented oil fill cap. The valve cover is bath tub. no water or crud can get in it. The cost was worth the $. There always is one on Ebay. The Wayne, Offenhauser, Fenton.etc valve covers are cheaper but at the moment not in production. I made some inquires and Offenhauser broke their mold and MAYBE be back up in 2017. The caw looks more original not too flashy, with a little history.
