i know the pvc filter is in the rear of the valve cover with the rubber hose that connects from it to under the carb, i have a oil fill cap but there is a hose that goes from the valve cover to the air cleaner, does anyone know what it is. its similar to a 69 amc rebel from my looks online

 

The crankcase is vented to the intake, therefore the crankcase does not build up pressure.