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Discussion Starter · #1 ·
Hello, iam in need of ideas on how to vent my crankcase.
My set up is a 355 with a 6-71 blower, and dual holley 600's. It pushing around 600hp. The engine has breathers in both valve covers.
My problem is it is pushing oil out of the breathers, and making a mess under the hood, plus burning onto my headers. Also pushing out the valve cover gaskets.
I would like to run a pcv valve, as i have been reading alot about it on here, and seems the best way to go.
My question is, do they make a pcv valve that fits the grommet size of the breathers, or do i need to drill another hole in one of my valve covers?
Also if i do need to drill for the pcv valve, do i need to block off the hole, and not use the breather on that valve cover?
Do i just run the vacuum to one of my carbs, or do i need to (T) the line to both the carbs?
Will this be enough to give me proper ventilation?
The car is a street car, (just a weekend cruiser) but sees alot of high rpms, 3000-7000+ rpms quite often. It has 456 gears, so rpms are always high.
I have read about the catch cans off the breathers also, is this an option i should look into, if the pcv valve is out of the question.
I have mufflers, and pipes back to the rear axle, so i don't think running it into the exhuast will work do to backpressure issues.
Any advice on the best way to set this up would be greatly appreciated.
Thanks,
Daryl
 

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A PCV valve will not work with two breathers! PCV/Fittings are available to put PCV valve in existing grommet or in a line from non vented valve cover to vac port on carb base.

PCV has to draw air from the vent on one side thru the engine to the unvented cover. Then thru the valve to vacuum source.

Works fine on my daily driven blown SBC
 

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AKA Lee in KC
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Here is my PCV set-up. There is a breather on the other side...



This set-up works fine for normal driving, but when I stick my foot in it and get into boost (I have a gauge), I blow oil out the breather. I tried removing the PCV valve (inside that billet piece) and just running a straight -6 line to the carb. This cured the oil-out-the-breather problem, but I was sucking a lot of oil into the induction system and was fouling plugs. Also this had the effect of a big vacuum leak and really leaned out the mixture. Fortunately I am intentionally running pretty rich so I didn't get into detonation. I only ran the set-up without the valve for a short time.

There are air/oil separators and catch-cans available. I have decided to just live with the oil blowing out, since I rarely get on it. I put a wrist sweat band on the breather and it catches most of the oil.
 

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Discussion Starter · #6 ·
Thanks for the help guys. I have heard that the moroso evac kit only works with open headers. I have exhaust out to the axle with mufflers. Is this true? or can it be used in my situation also.
Thanks again for all your help.
 

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http://www.warsprints.com
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uplateagain said:
Thanks for the help guys. I have heard that the moroso evac kit only works with open headers. I have exhaust out to the axle with mufflers. Is this true? or can it be used in my situation also.
Thanks again for all your help.
I have seen pics of these evac systems with mufflers. The kit should come with a 1 way valve to prevent any backpressure from re-entering the crankcase. You have to install the fittings in the exhaust at an angle (not straight in) toward the exhaust flow. I made my system on my son's 461 BBC S10 and it seems to work great but then again, it has open headers as it is just a drag truck. I think a better solution would be a vacuum pump.
 

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The Smell of Nitro in the morn
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Like I said before the system does work, Im running 3" exhaust all the way back.
It works open header or full length exhaust.
I do have a vacuum pump for sale, been there done that, big waste of $$$.
 

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My pipes are my music
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Or, you can get a set of valve covers that have dual 5" tall breather's. That will keep the oil from splashing on the underside of the breather cap's and being forced out under crankcase pressure.
 

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same set up

uplateagain said:
Thanks for the help guys. I have heard that the moroso evac kit only works with open headers. I have exhaust out to the axle with mufflers. Is this true? or can it be used in my situation also.
Thanks again for all your help.
I have the same set up as you, headers, closed exhaust past the axle and out by the bumper. I have had this system on for 18 years without a problem. Used to blow oil all over the place before I instaled a Moroso evac kit. I don't drive mine easy either! :D ........CR
 
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