Right. But how often is a vehicle sitting still and running? For all practical purposes, does a pcv system really matter on a 74 year old truck? Will the advantages be noticeable? If it's only being driven a few thousand miles a year and/or gets it's oil changed every 3000 miles, will there be any real difference that should be considered?
Probably the best answer to your questions is for you to decide. In California, my 70 year old truck is now exempt from emission control compliance. The PCV system was left on the truck after exemption and the engine still runs well with no ill effects, perhaps extending the life of the engine too. The closed PCV system is doing its small part to protect the environment.
