Positve Pressure Where it Ain't
Bob Ford, in reading your remarks, and what you think it ain't let's think of what it is. Have you removed the filler cap in an attempt to releave this high pressure? Can you hear any pumping sounds from the crankcase when the filler cap is off? Does the exhaust sound normal? How about the cooling system level and collor(any oil there?)? If it were me I would drive with the filler cap removed and a piece of cheese cloth afixed at the opening, this will stop any oil from being blown out from the overhead oiling system and crankcase pressure. You have a regular Hitchcock so stick to it and maybe others will be able to had to your help wanted. Happy Trails Beep Beep from Houston.
somemore blow hard whoops I'm meant Blow-by