47-55.1 oil seperator

[dsraven]

the original system used the oil filler cap as the fresh air in, if it needed any fresh air to come in then there was an opportunity for that to happen. it was originally not a very large cap, as I remember anyway, and I think it used to have some course mesh screen inside it. maybe somebody can comment on that.
the draft tube was the exhaust port for internal engine pressure to escape and, by definition, it created some draw, or draft effect, when the vehicle was driving because air at road speed passed the end of the tube created a slight draw on the pipe. back in the day the tube was an actual pipe with a slash cut on the end and hung down at the level of the bottom of the engine, right in the wind.more modern cars upgraded to a rubber hose back there that lost the draft effect. on a 6cyl engine the baffle system was built into the tube up near the engine block insertion hole. on the sbc it was the canister inside the block lift valley. some of these were removed back in the day because some low intake manifolds would hit the baffle can. it was common for guys to use an inch and 1/4 plug in the block hole and then use the valve covers with holes to mount a pcv valve on one side and breather/filler cap on the other, then remove and plug the old oil filler tube at the front. some kits sold a rubber grommet that that fit into the draft tube hole and was fitted with a pcv valve that would connect to intake vacuum at the carb base or simply a fitting in the manifold. the inlet for that system to gather fresh air was the oil filler cap on the metal tube at the front of the intake and these often got an upgraded cap that would allow better air flow through the cap but were also larger in size. you could do this as well and if you are worried about drawing engine oil from the block at higher rpm an oil catch can could be placed up high in the pcv valve line. if you look at goggle you will likely find all sorts of oil catch can set ups and descriptions of how they work and how they can be remotely mounted so draining the can is made easier. the elaborate ones would be for the higher rpm race style engines that would produce more internal pressures. engines with turbo chargers or blowers also have some elaborate breather systems due to their increased pressures and their large fluctuations in intake vacuum and pressure as they go from vacuum to boost pressure.
anyway, a little research can go a long way here but I'm sure you will find that a normally operated small block with fairly stock internals could get away with a fairly simple pcv sytem