If I was guessing I'd say the pvc system was plugged. When I got back from over the pond in '64 my Dad had a '57 Ford Custom waiting for me. California was just starting their smog BS and the '57 had been converted. A couple of months later as I was driving down the street a hell of a noise erupted from under the hood. The dipstick was blown out and oil was all over the right side of the windshield, made a hell of a dent in the hood and for all pratical purposes wiped out the bearings. You should have seen the mess it made on my Dad's driveway when I pulled the rubber plug that had been shoved up the road draft tube.