When I ran a shop in central California in the late 1970's, the Californicators in the state legislature decreed that all vehicles on the road, regardless of age, had to be retrofitted with a closed crankcase vent system. Several kits became available to block off the road draft tube, replace it with a PCV valve, and install an air inlet into the engine coming from the "clean" side of the air filter. For several years afterward, I installed many of those kits. Some were pretty generic, involving a lot of fabrication and adapting to individual vehicles, while others were either engine-specific, or at least they fit a particular general design of engine. The ones for stovebolt engines used a rubber 90-degree elbow that was attached to the road draft tube after it was cut off just above the oil pan rail, and a PCV valve was inserted into the elbow with a vacuum line running to the intake manifold. Fresh air was introduced into the engine by installing a 90 degree elbow over a hole drilled in the valve cover with sheet metal screws, and another nipple that was attached to the "clean" side of the air filter by cutting a hole under the nipple and attaching it with sheet metal screws. A piece of 5/8" heater hose connected the two nipples. If the engine had a vented oil filler cap, it was replaced with a sealed type. Any other vents, such as slots in the valve cover, had to be brazed or welded shut. At the time this was happening, cars had to be "smog checked" every year before license plates were renewed. Roadside emission testing was also done, similar to DUI checkpoints. When those procedures got too expensive to continue, the smog check was required only when a vehicle changed ownership, or a car was ticketed for emitting visual smoke. I haven't seen PCV conversion kits for sale anywhere in the past 25 years, and even back then, it was mostly a California thing, not nationwide.
Jerry
