The PCV valve comes apart. There is a valve and a spring inside. The valve has a hole in it. Sucking on either end you are sucking air through the hole. Manifold vacuum should open the valve. Take it apart and clean it.
Somewhere in the mid '50s they were changed from an oil bath breather to a paper filter one. That may be the smaller/bigger you noticed. The one on my Suburban is the
paper filter one from a '59.
