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Hot Rods Help with 327 breather

Discussion in 'The Hokey Ass Message Board' started by Grm5959, Jul 27, 2018.

  1. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

    So I'm running a 327 and I have the separator under the intake. I'm running a manafre intake with 4 2bbl carbs. What's the best thing to do with the hole in the back of the 327? This is something new tome as all my other cars had breathers in the valve covers. I'm running old cal custom covers with no holes. Thanks
     
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  2. Deuces
    Joined: Nov 3, 2009
    Posts: 21,954

    Deuces
    Member
    from Michigan

    I wonder if a freeze plug could be installed with a hole drilled through it for a grommet and pvc hooked up....???? Yes???? No????:confused:
     
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  3. You need to figure out your PCV system. It needs fresh air in (Breather on VC or fill tube) and a vacuum source hooked into that hole, usually the back of the carb
     
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  4. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

    I will be running a breather on oil filler use in front of I take.
     
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  5. DDDenny
    Joined: Feb 6, 2015
    Posts: 16,059

    DDDenny
    Member
    from oregon

    GM had a couple different pcv systems over the years. 20170630_143459.jpg
    This is a fresh air tube circa 64-68, used on most of the higher hp small blocks, it connects the port adjacent to the distributor to the air cleaner base, pc valve threads into oil fill tube in intake manifold with hose going to carb baseplate.
    The style of air cleaner(s) will generally dictate the system used.

    [​IMG]

    [​IMG]

    [​IMG]


    [​IMG]


     
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  6. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 9,098

    mgtstumpy
    Member

  7. speedshifter
    Joined: Mar 3, 2008
    Posts: 312

    speedshifter
    Member

    On an early 327 I believe a road draft tube was connected to the hole in the back of the block. A filler pipe with a breather cap went into a hole in the front of the intake manifold. Valve covers were not vented. Not the most efficient design but correct for an early small block.
     
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  8. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

    With 4 2bbl carbs and mini air cleaners there is no option to go yo air cleaner. Not sure if a man a fre I take has a port. Will have to look.
     
  9. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

  10. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 9,098

    mgtstumpy
    Member

    I feel that you wouldn't want to however there are those two(2) casting bosses visible on the upper side of the intake, they could be drilled and tapped for an NPT thread and a barbed fitting? You'd most likely have better (Consistent) vacuum from there compared to the other ports that can be seen under the carbs on your intake which have not been drilled and tapped as per my earlier post. I've a 6x2 X1 and am reluctant to alter it being an original intake. Last thing I want to do is drill any holes however I require a vacuum source so I'm drilling at the very back and hiding vacuum so it's out of sight and what can be seen will look OEM when finished.
    upload_2018-7-28_8-39-31.png

    upload_2018-7-28_8-37-20.png
     
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  11. Oilguy
    Joined: Jun 28, 2011
    Posts: 632

    Oilguy
    Member

    DSC07982.JPG Get the 90 degree adapter for the road draft port and run a hose to a PCV valve at the carburetor. Use the filler/breather tube as GM did. This is a factory method used in lieu of the draft tube.
     
  12. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

    4 2bbl carbs.
     
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  13. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

    Thanks but I hate to modify an original intake that is pretty rare. I truly appreciate the pics and the input.
     
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  14. Deuces
    Joined: Nov 3, 2009
    Posts: 21,954

    Deuces
    Member
    from Michigan

    You could always use 1" tall risers for the carbs with holes drilled and tapped on the side for a vacuum fitting....
     
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  15. Moriarity
    Joined: Apr 11, 2001
    Posts: 23,061

    Moriarity
    SUPER MODERATOR
    Staff Member

    Are you cloning the AG Milner coupe? If so the answer is simple . Look at pics of the real car and do exactly what they did. I have a man a fre on my 61 vette. My car has a 350 so I had to run pvc. Because the man a fre is effectively an IR manifold I had to put a fitting in each carb and t them together for the pvc .If I had a 327 and a man a fre I would absolutely run a road draft tube.

    Here is a question, if you are cloning Milners car, do you have enough guts to put the correct tires on it? I don’t think anyone has done it correctly yet.....


    Sent from my iPhone using The H.A.M.B. mobile app
     
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  16. joel
    Joined: Oct 10, 2009
    Posts: 2,122

    joel
    ALLIANCE MEMBER

    You should have pipe plugs in the base of your carbs. I would make a manifold for vacuum with 2 90 deg hose fittings where the pipe plugs are and 2 lengths of hose into both legs of a T fitting, then to the draft tube fitting like shown in post #11. In fact that's exactly how I'm going to do it when I get there on mine
    IMG_1008.JPG IMG_1009.JPG
     
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  17. tinkirk
    Joined: Jan 16, 2017
    Posts: 111

    tinkirk

    My thoughts are go for it and see what happens
    I think u are on the right track


    Sent from my iPhone using Tapatalk
     
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  18. Blues4U
    Joined: Oct 1, 2015
    Posts: 6,465

    Blues4U
    Member
    from So Cal

    You could use a kit that adapts a PCV into the road draft tube, then plumb that to the carburetors. However, it would be best to share the duties across all 4 carbs so that the mixture to each cylinder is equalized. For that, there are brass pipe plugs in the base of the carbs (visible in your picture above). Plumb a series of fittings and piping so that all are connected and then connect the pcv to that. But I would do as Moriarity said and just use a road draft tube & breather cap on an oil fill tube. That would be period correct. It isn't the best way to ventilate an engine, but it will do. You will likely get some fumes emanating from the breather when stopped at a light, or when cruising slow enough that a draft is not created at the draft tube, but that's how all the early Chevy V8's worked.
     
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  19. Blues4U
    Joined: Oct 1, 2015
    Posts: 6,465

    Blues4U
    Member
    from So Cal

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  20. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

    I can't tell from all the pics what they did there. A clone? Well not really as I'm doing some things differently and tires??? You got me there. Bias ply tires on my sc rambler. Not on this car.
     
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  21. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

    Thanks very much
     
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  22. Moriarity
    Joined: Apr 11, 2001
    Posts: 23,061

    Moriarity
    SUPER MODERATOR
    Staff Member


    if you are not cloning the car it is no big deal. I would run a road draft tube on a 327 with a man a fre.
     
  23. Grm5959
    Joined: Dec 22, 2015
    Posts: 63

    Grm5959

    Thanks agin very much
     
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  24. Mike VV
    Joined: Sep 28, 2010
    Posts: 2,581

    Mike VV
    Member
    from SoCal

    Don't see a problem...

    You have two places to release vacuum from, the front tube and the rear breather. You don't say if you are installing a PCV system, thought...others do..!

    You can always do what I did when I had a Man-a- Fre in my 56 Chevy... I built my own air filter. Used a BIG Chrysler filter (don't recall what it was originally for), two sheets of aluminum, four of the short Man-a Fre velocity stacks (yes he sold short ones and long ones). Screwed the lower alum sheet to the velocity stacks and used three studs to hold the top to the bottom. Not pretty, but very effective.

    I didn't run a PVC system in my car. Just breathers on the rocker covers and the tube in the front of the manifold. And yes, a freeze plug in the back of the block.

    If you want vacuum, drill into the connector passage between the carburetor pads. If you want to keep it clean, you can always open a hole...underneath the Man-a-Fre " plate" is it was called (it's not...a manifold as the term implys). I would not go into just one, of the "injector" locations, as you see little volume of vacuum, and it will pulse from just being connected to two cylinders.

    Mike
     
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