47-55.1 oil seperator

[nvrdone]

On my 327 I have the oil separator under the intake manifold. There is a firring on the back of the block where the road draft was. That leads to a hose with a pcv valve which leads to the base of the carb. There is also a vented oil fill cap.
If I remove the road oil separator will I have enough vacuum to work the system? I don't want to cut a hole in the valve covers

[mr48chev]

I'd clean it and leave it in place. You are more liable to have the PCV valve suck oil in without it than have any actual vacuum issue one way or the other. Same as the valve covers that don't have a deflector under the PCV valve

The positive crank case ventilation system works on air in, air flow through and being drawn out by the engine's vacuum

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That is one reason that V8 Chebbys with a breather in both valve covers and No PCV or draft tube always have oil on the valve covers and oil leaks. The pressure in the crankcase has to go somewhere. I got that education on the 283 that I had in my T bucket and then in the 48.

[nvrdone]

OK, so how do I clean the oil separator with out removing the intake manifold? Since the pcv is in the hose from the fitting where the road draft tube was up to the carb base will that give enough ventilation?

[dsraven]

there are a few threads on the pcv subject for sbc's. look for a
road draft tube conversion
thread on this site

the sbc's had a baffle inside the block at the rear, above the main oil gallery and lifters, that acted as an oil collector. does your engine have that? are you using the original oil filler tube at the front that had a push on oil cap with steel wool style screening inside it to act as a filter of sorts?

[dsraven]

today I am unable to attach a link to the thread, sorry.

[dsraven]

in the search box next to your log in box on this site, type in
road draft tube plumbing
click the dot that indicates web or 67-72 chev trucks so it says 67-72. then hit enter. it will come up with a few threads for you to see how others have done it.

the site does't let me copy and paste the links or i would have done that for you

[Rickysnickers]

Here's the link to all the threads Dennis mentioned.

https://67-72chevytrucks.com/vboard/...archid=7530635

[nvrdone]

Guys - thanks for the feedback.
I have a "can" in the rear of the valley under the intake. Then it connects to a hole where the road draft mounted. Along time ago I removed the road draft tube and pit a fitting in the hole, ran a hose with a pcv valve up to the base of the carb. This was to satisfy CA emissions back in the 70's. I didn't want to punch a hole in the valve cover because they are Corvette aluminum covers. Now I'm chasing oil leaks and I'm thinking that oil separator is plugged up causing too much internal pressure.

[nvrdone]

WOW !!! After reading all this info my head is about to explode !!!
So here's my thoughts -- can I remove the oil separator, run a hose with a pcv valve into i a vacuum port. And then use an oil fill cap that is vented with mesh in it? Would this give me proper venting with out sucking all the oil out of the crank case??
Any thoughts?
Thanks

[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