Thoughts on "Valve Cover Breathers" & "Location"

Discussion in 'Big Block Cadillacs' started by bugzaper, May 24, 2018.

  1. bugzaper

    bugzaper Well-Known Member

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    Since I've pretty much decided to go with the after-market rocker systems and scrap the stock and already have a set of aluminum tall valve covers, I now need to decide where to locate the breathers and what type to use.
    I really hate having to cut holes in them but, know an engine must breath.
    Thinking about "2" on each side equally spaced.
     

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  2. MIHELA

    MIHELA Active Member

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  3. 53 Studillac

    53 Studillac Active Member

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    I think on my next valve covers I am going to weld an "AN" bung and plumb hoses to a catch can with a breather on top. I've ran open K&N breathers before but seems to always be some oil mist on the valve covers or some seepage around the grommets even with baffles. The bung can be at the back or side to keep the top of the valve covers smooth. But you have to have a way to put oil in too.
     
  4. bugzaper

    bugzaper Well-Known Member

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    Oil seepage is something I'm concerned about also.
    I've looked at a few "Circle Track" cars and kind'a like how they attach the covers with a cross over tube and have duel breathers mounted in the center of the cross over tube.
    But, they do take up a lot of room and you have to alter the air filter size on some.
     

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  5. bugzaper

    bugzaper Well-Known Member

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  6. MIHELA

    MIHELA Active Member

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    We will see when I start it up.
     
  7. 48Austin

    48Austin Active Member

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    This is not new. Pontiac did this in the early '60's on the SD 389's and 421's. NASCAR and drag cars. It was an evacuation. pressure balance. Also to keep the oil in the pan where it belonged.
     
  8. El Diablo

    El Diablo Active Member

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    If you are running exhaust headers, could you use a "Pan e vac" setup? It will help with ring seal and probably free up a pony or two.
     
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  9. 48Austin

    48Austin Active Member

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    The panevac system has MAJOR drawbacks. One, it does nothing at idle. Two, it basicly does nothing at part throttle. Three, if the bungs are welded in wrong, it could suck the oil pan dry at WOT. I have seen that happen. I would run 2 PCV's at the front or middle of the valve covers to make sure the oil wouldn't get sucked out. But make sure to baffle them. The other thought is to run the balance tube with a PCV in the middle.
     
  10. bugzaper

    bugzaper Well-Known Member

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    Thinking about going with something along these lines.
    Run ports on the back side of each valve cover into the box and vent the box down the fire-wall.
    Will still have to figure out an inlet for oil.
     

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  11. 48Austin

    48Austin Active Member

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    If you are thinking of going with a German system. My advise would be to take a hard look at the system. Get valve covers and cut the baffle plates out. Then look at the rest of the plumbing. I know a lot is plastic and it breaks. BUT the Nazi's did these things for a reason. They knew how to circumvent the ECU's. Didn't they? But the best bet is to run a valve cover crossover and one PCV. Just like Pontiac did in the late '50's early "60's. Worked then, and still now with the roundy-round guys.
     
    Last edited: Jun 9, 2018
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  12. El Diablo

    El Diablo Active Member

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    Just another brainstorm idea. On my old Cadillac 390, the road draft tube was plumbed into the valley cover.
    Would it be possible or practical to bore a hole in the back of your intake manifold for a grommet for a breather, PCV valve or road draft tube? This may assist in pulling oil from the top of the heads back down into the valley without the worry of sucking the oil out. Plus you can have smoother looking valve covers as well.
     

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