The owner's manual of my 1963 Pontiac Tempest specifically mentioned its engine having the PCV valve vs road draft, noting that crankcase vapors are 50x more concentrated in pollution than exhaust fumes. Everybody running that Pontiac four banger does the factory PCV conversion, which consists of a rubber grommet for the valve in the rear of the camshaft cover, then the valve and hose going to manifold vacuum. All three years had the steel wool filled ventilated oil cap so that could stay the same. PCV also provides a negative pressure environment inside the crankcase, which aids piston ring sealing. As well as greatly reducing hydrocarbons.. PCV was the cheapest, lowest hanging fruit that auto makers could pluck to begin compliance with US emissions laws. In addition to being a good idea in general.
