Valve cover O rings

[khales]

I can not for the life of me find the specs for what size o ring should go under the valve stem cover. Does anyone know what the stock spec is for a 1977? I've got a slow peak coming from there and I'm getting tired of feeding the thing oil.

 

[Scorpio1963]

Take one of yours off and go to the local hardware store.I have had good luck matching up rubber orings that way.