Either put a grommet into the other valve cover and run a fresh air tube to the "clean" side of that Cadillac air cleaner, or put a ventilated cap on the oil filler (wherever that happens to be). Crankcase ventilation has to have an air inlet somewhere to avoid creating a big vacuum in the crankcase and sucking up oil.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!