I posted several days ago about oil leaking from oil filler cap on top of valve cover. My fears were that excessive crankcase pressure was causing problem even though I had cleaned flame trap, etc. Thanks to several respondants, I changed gasket on filler cap and it seems to work well. Although the old gasket looked pretty good, when you take it out and hold it next to new gasket its evident age and heat have done some damage. Thanks to all.