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Crankcase ventilation

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Old 04-18-2013, 04:01 PM
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Fredscott
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Default Crankcase ventilation

I have a 406 in my 82 and it runs great....very strong and very fast. My situation is this...when I run the car hard (80-120) i get oil dripping out of the breather on the driver side cover (ventilation intake). The passenger side breather is run to an oil capture tank that is under vacuum from the carb.
Is it normal to have some oil escape on the intake side of the ventilation system under extreme conditions? Is there anyway to correct this?
Thanks
Old 04-18-2013, 04:05 PM
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aaroncorvette
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Not sure, but I have mine the other way round to you it seems and mine is fine, Drivers side with PVC valve going to the carb and pass side open for drawing in air.

I have a hot 355 by the way, not stock at all.
Old 04-18-2013, 04:46 PM
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MelWff
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Does the valve cover with the leaking breather have any kind of baffle inside to prevent your problem.
Old 04-18-2013, 05:17 PM
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QIK59
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Originally Posted by Fredscott
I have a 406 in my 82 and it runs great....very strong and very fast. My situation is this...when I run the car hard (80-120) i get oil dripping out of the breather on the driver side cover (ventilation intake). The passenger side breather is run to an oil capture tank that is under vacuum from the carb.
Is it normal to have some oil escape on the intake side of the ventilation system under extreme conditions? Is there anyway to correct this?
Thanks
You're getting blow by under high load high rpm conditions - common occurence.

Now try and figure out a way to "separate and capture" the oil mist in the blow by air ?

Should get lots of suggestions to work with on here.
Old 04-19-2013, 12:15 PM
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aaroncorvette
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Change your set up so it's like mine and you should be fine, I don't need an oil catch tank so you shouldn't either, these aren't race cars, let the air draw in the pass side with a breather and put a PCV valve on the drivers side to the carb to burn the blowby
Old 04-19-2013, 12:23 PM
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aaroncorvette
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Old 04-19-2013, 05:26 PM
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gdh
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Maybe I'm confused, are you running 2 breathers or is the passenger side actually a pcv which you run into either an air/oil separator or a vacuum pump to the carb?
Old 04-19-2013, 11:57 PM
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TheSkunkWorks
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FWIW, if you end up going so far as to vent both valve covers to an oil breather tank (what I'm leaning towards doing) and that still doesn't solve it, IMHO you really need to look more carefully at the blow by end of the equation before considering further action on the ventalation end. My $.02
Old 04-20-2013, 10:08 AM
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chevymans 77
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Put it back like the general had it,

PCV on one valve cover and tube the other into the air filter base if your running an open element if not tube it into the snout of the air filter housing in between the smallest area of the housing and the filter.

When an engine is at WOT it will produce very little vacuum for the PCV but the air flow within the filter is tremendous and will provide the needed air movement to pull the vapors into the engine to be burnt.

Neal
Old 04-20-2013, 11:01 AM
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aaroncorvette
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Originally Posted by gdh
Maybe I'm confused, are you running 2 breathers or is the passenger side actually a pcv which you run into either an air/oil separator or a vacuum pump to the carb?
Hi, drivers side is a PCV valve going to the carb

And yes the picture looks a little confusing but the pass side is simply a breather with wire wool in which gets it's air from the base of the air cleaner.

No issues up to 7K
Old 04-20-2013, 01:43 PM
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gdh
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gkull posted a link to n informative article re: hipo engines and blowby. My engine was designed to run the 1/4 by MountainMotor whom some of you longtime C3ers may remember. He used to build NASCAR engines then 1/4 mile drag boat engines. He got me all the parts at his cost and race ported the heads for free and port matched the single plane intake. I had blowby from day 1, just the nature of the rings used as well.
I would keep your PVC in the passenger side as don't think it would have much difference unless for some reason you had cheap valve covers and the hole was located right above where oil enters your heads and there is no baffle in the cover either. You can always put an air/oil separator on the drivers side btn the tube coming out of your vc and the base of your air intake. I know gkull recommends using a vacuum pump for this.

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