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Technical 327 with no oil filler and breather

Discussion in 'The Hokey Ass Message Board' started by jugheadjones, May 29, 2022.

  1. jugheadjones
    Joined: Jun 6, 2011
    Posts: 182


    I have found a lot of threads that have ALMOST answered my question.

    I have a 327 with the original oil separator canister removed which I have replaced with a PCV valve plumbed to the back of the intake.

    1. I have an intake without the original oil filler neck (I don't want to install an oil filler neck)
    2. My valve covers don't have breathers nor do I want to drill holes in them (original corvette ones)
    3. I am happy to add oil via removing a valve cover (super simple in my situation)

    My question is: I'm assuming I need an "air in" somewhere? If so, is there something simple I can install into the intake manifold to get around this? The intake isn't installed yet so I can modify what I need.

    Many thanks.
    knotheads likes this.
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 54,493


    yes, you can install an oil filler tube.

    Or you can remove the plug from the back of the block, and install an oil separator canister under the intake.

    Or you can put a breather or two in the valve cover(s).

    Maybe you could put a breather in the intake manifold, somewhere where there isn't an intake port in the way.

    Amazing how folks make life hard for themselves, by not using the original design, which actually works.

    (also...the reason you need an air "inlet" is really so the blowby has somewhere to go when it is greater than what the PCV valve can handle. Or it will blow gaskets out, or whatever else is handy)
    Last edited: May 29, 2022
  3. Sage advice as always,,,,from Jim .

    427 sleeper likes this.
  4. The factory knew a lot when they designed venting that engine.Really good venting prevents moisture sludge from gumming up the inside of your engine.I would cut down a filler tube so it doesnt stand out so much,and call it good.The only other thought is vent the tin timing cover some how.You would be reinventing the wheel so your on your own there.It would prevent blowing seals,but would it move the volume of air needed to correctly scavenge the inside of the engine? You would need to change oil a lot more often just to try,and keep it clean inside.

  5. sunbeam
    Joined: Oct 22, 2010
    Posts: 6,127


    Like Jim said blow by increases under full throttle and PVC uses vacuum and it goes away under full throttle.
    jugheadjones likes this.
  6. I personally like the oil fill tube on the intake. Gives your sbc a vintage look.
    But it's whatever floats your boat...
  7. goldmountain
    Joined: Jun 12, 2016
    Posts: 4,253


    Years ago, when I worked at a garage, a guy came in with a truck that he had just put a crate engine in. The valve cover still had a plastic plug in it where the filler hole was. The engine made a really strange screaming noise. We managed to fix it by removing the plug. The engine needs to be vented somehow.
    jugheadjones and Tman like this.
  8. DDDenny
    Joined: Feb 6, 2015
    Posts: 17,884

    from oregon

  9. Unless you're only expecting to run the engine long enough to load and unload the vehicle from a trailer, I suppose.
    jugheadjones likes this.
  10. 1971BB427
    Joined: Mar 6, 2010
    Posts: 8,431

    from Oregon

    Using an intake with the fill tube up front will work as a place to fill oil, and also can be equipped with a breather cap too. That's all you need with your PCV valve at the rear. Even if it's easy to pull valve covers to dump in oil, it's a poor choice if you happen to stop somewhere and check oil level, and it needs a quart. Will you carry a set of valve cover gaskets too? Seems illogical to me when it could be done much easier with a breather tube up on the intake.
  11. MCjim
    Joined: Jun 4, 2006
    Posts: 799

    from soCal

    What are you thinking?! An oil fill tube on a SBC is so "traditional and period correct" !
    guthriesmith, ottoman and Tman like this.
  12. jaracer
    Joined: Oct 4, 2008
    Posts: 2,192


    When I worked for the Dodge Dealership, we would get cars in with milky looking oil and oil leaks everywhere. About 99% of the time it was caused by the valve cover vent cap being plugged. Replacing it solved not only the milky looking oil; the oil leaks also stopped. In order to properly vent the crankcase you have to have a path for air to get in as well as out.
  13. Fogger
    Joined: Aug 18, 2007
    Posts: 1,779


    I have three running cars with early sbc engines, each has the oil separation canister and a pcv valve connected to the carburetor base. Each has a intake manifold with the front fill tube and a breather cap. My suggestion is remove and replace the intake manifold with one that has a oil fill tube and while you have the manifold off replace the oil separation can. All my cars run the aluminum Corvette valve covers. Be aware that GM had two canisters, a short one for the 4-barrel manifold and a longer one for the 2-barrel. Without the canister you may have excessive oil fed into the intake.
  14. NoelC
    Joined: Mar 21, 2018
    Posts: 668


    I can speak with experience, if you don't listen to what Jim has said in post #2, you will very quickly discover your mistake in not following his sage advice.
  15. Oilguy
    Joined: Jun 28, 2011
    Posts: 663


    Sounds like an intake for a large journal block on a small journal block. Don't know how you can make that work without a breather tube. How do you replace an oil separator with a PCV valve? What about the port in the back of the block; did you plug it? Many of the large journal motors used a breather on one valve cover and a PCV in the other. The port at the rear was eliminated as was the breather tube.
    Are you saying you installed a PCV in the large hole for the baffle under the intake? I am confused but then I am also kind of slow.
  16. I have seen mini breathers mounted in various places 20220529_114238.jpg 20220529_114247.jpg
  17. blowby
    Joined: Dec 27, 2012
    Posts: 8,656

    from Nicasio Ca

    I was thinking the same thing. If you absolutely weren't going to use the intake of valve covers, maybe drill the block in front of the intake manifold, a head or maybe the top of the timing cover, and finagle something in there. Not saying it would work, or even possible..
    jugheadjones likes this.
  18. jugheadjones
    Joined: Jun 6, 2011
    Posts: 182


    Thanks for all your responses.

    1. If I was to install an oil filler tube on my new manifold can the tube and breather sit low? Essentially sitting in the valley?

    2. And does it need to be up front on the manifold? I have room to install it on the back of the manifold?
  19. To work most effectively, if the PCV valve is at the back of the engine the vent should be at the front. Or the valve should be in the valve cover on one side with the vent on the opposite side cover, at least on a V-style engine.
    jaracer, jimmy six and brEad like this.
  20. gimpyshotrods
    Joined: May 20, 2009
    Posts: 22,926


    What manifold are you working with here?
  21. @jugheadjones it would help if we knew why you want to do this.
  22. jugheadjones
    Joined: Jun 6, 2011
    Posts: 182


    It's a hi rise style.

    Baumi likes this.
  23. jugheadjones
    Joined: Jun 6, 2011
    Posts: 182


    Thank you.
  24. jugheadjones
    Joined: Jun 6, 2011
    Posts: 182


    Thanks for the info.

    If I was to put the oil separator canister back on and run a remote style breather? My thoughts - drill and tap the valley, run a fitting with a flexible hose to which a breather is fitted to the end? Here's a pic of the engine.

    Tickety Boo and Desoto291Hemi like this.
  25. Sometimes you gotta do what you gotta do not what you wanna do. Those vette valve covers turn all the time already drilled for breathers.
    SS327 and jugheadjones like this.
  26. jugheadjones
    Joined: Jun 6, 2011
    Posts: 182


    Not ideal removing a valve cover to add oil but I'm happy to do this if I need to. I use phillip head bolts for the valve covers. Super easy to remove in my case. The cork gaskets given they're not crusty and dry have lasted me years off and on so far.

    I was thinking of putting the oil separator canister back on and build a remote style breather? Drill and tap the manifold, run a flexile hose to a breather?
  27. jugheadjones
    Joined: Jun 6, 2011
    Posts: 182


    I've posted something similar to your idea in the comments below.
  28. jugheadjones
    Joined: Jun 6, 2011
    Posts: 182


  29. TA DAD
    Joined: Mar 2, 2014
    Posts: 1,004

    TA DAD
    from NC

    Team G manifold ?
  30. Mr48chev
    Joined: Dec 28, 2007
    Posts: 33,066


    It looks like there is plenty of room between the water crossover and where the front runners V to put a filler tube and discrete breather. With those runners I am thinking Race only with no or very limited street use? 327 big intake (2).jpg

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