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Technical Flathead Internal Breather Tube details?

Discussion in 'Traditional Hot Rods' started by Dad Was A Racer, Jan 4, 2018.

  1. Dad Was A Racer
    Joined: Oct 7, 2014
    Posts: 138

    Dad Was A Racer
    ALLIANCE MEMBER

    My 8BA block is missing the internal crankcase breather tube. This is the standpipe that fits in the floor of the lifter valley (1-5/16" hole) and runs up to somewhere about the level of the intake. Since I don't have one to measure, I'm looking for dimensions that it needs to be so that I can fab one up. There doesn't seem to be a source for a replacement, so necessity being the mother of invention, etc. I know it's supposed to be there because my "build books" show installing it back in the motor. Any help?
     
  2. Vanness
    Joined: Aug 5, 2017
    Posts: 410

    Vanness
    Member

    I’d like to know as well I had some bare 8ba blocks I tried to removed them and they were froze worse than the pistons and crank :(
     
  3. Dad Was A Racer
    Joined: Oct 7, 2014
    Posts: 138

    Dad Was A Racer
    ALLIANCE MEMBER

    Another source came to the rescue with 1.3" by 5.480" and it's apparently just a hollow tube with no special baffle inside, etc.
     
    dan c likes this.

  4. Vanness
    Joined: Aug 5, 2017
    Posts: 410

    Vanness
    Member

    Nice. Looks like you made one. I wonder if you could run without that inside portion?
     
  5. If you have the intake you can measure the depth to insert the tube and add that to the dimension from the block down to where it inserts. If I remember, it stuck up above the block about an eighth inch.
     
    ghector23 likes this.
  6. flathead4d
    Joined: Oct 24, 2005
    Posts: 897

    flathead4d
    Member

    Also, go to the fordbarn.com web site and click on the early V-8 32 to 53 section. Anything you want to know about a flathead is there.
     
  7. Dad Was A Racer
    Joined: Oct 7, 2014
    Posts: 138

    Dad Was A Racer
    ALLIANCE MEMBER

    Not yet.... Gotta locate some 1 5/16" tubing today (or close to it that can be honed to fit). I THINK the internal tube needs to be there to prevent oil from just running down the breather hole and preventing air flow.
     
  8. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,833

    V8 Bob
    ALLIANCE MEMBER

    The 8BA front stand pipe is 1 5/16" od by 5.5" long. It is a simple straight pipe with no shoulder, like the earlier 59A pipes have. This pipe channels fumes/vapors up from the crankcase, through the intake gasket and into the road draft port on the late intakes. (The earlier '35-'48 pipe leads down to the the oil pan vent/road draft)
     
  9. flatjack
    Joined: Feb 13, 2007
    Posts: 953

    flatjack
    Member

    I'll gladly send you a tube for the postage. Message me.
     
  10. Petejoe
    Joined: Nov 27, 2002
    Posts: 11,327

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    Good opportunity eliminate it all together and install a PCV.
     
    Darryl Deir likes this.
  11. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,833

    V8 Bob
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    You do not want to eliminate it if the pcv is located externally on the intake, in place of the 8BA road draft tube. If the pcv is going to be under the intake, a shortened pipe is used and capped off with the pcv.
     
    Petejoe likes this.
  12. Dad Was A Racer
    Joined: Oct 7, 2014
    Posts: 138

    Dad Was A Racer
    ALLIANCE MEMBER

    Bob, I've read a lot of the discussions here regarding PCV's on Flatheads, and I'm trying to convince myself it's necessary and practical to do, especially on a 3x2 intake set up.
     
    Last edited: Jan 5, 2018
  13. flatjack
    Joined: Feb 13, 2007
    Posts: 953

    flatjack
    Member

    definetly do not want to eliminate that internal tube.
     
  14. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,833

    V8 Bob
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    If you want cleaner oil, no visible blow-by, and a cleaned up engine by removing the road draft tubing, installing a pcv is the answer, and pretty simple on a late (8BA) flathead. The valve can be installed in place of the stock road draft tube on the intake, like on my 2-carb '51, or on the shortened and capped off vertical stand pipe under the 3-carb intake, like on my '32.
    IMO, a pcv is a necessary, practical and responsible addition to any pre-pcv engine. :)
     
  15. Petejoe
    Joined: Nov 27, 2002
    Posts: 11,327

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    Yes I installed mine under the intake by capping off the tube.
    I’ve seen first hand evidence of the positive effect when removing my intake and viewing the lifter valley after 10 yrs of operation.
    Clean as a pin.

    pcv 1.jpg pcv 2.jpg
     
    Last edited: Jan 6, 2018
    fabricator john likes this.
  16. Petejoe
    Joined: Nov 27, 2002
    Posts: 11,327

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    Sorry to confuse. Thanks flat jack.
    Meant to say eliminate the stock vent system. Definitely need the tube.
     
  17. Dad Was A Racer
    Joined: Oct 7, 2014
    Posts: 138

    Dad Was A Racer
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    Bob, Can you please clarify for me the where/how you mount the PCV on a 3x2 intake? I get the design on the standpipe (shorten and cap it). But I've seen one design that used a piece of tubing welded to the stand pipe with rubber hose running to a PCV, and another where the PCV was threaded or plugged into the pipe with a grommet. So from there, where does the hose go on the 3x intake? I know there are threads concerning this arrangement, but after reading them and all of the various opinions, I'm pretty confused.
     
  18. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,833

    V8 Bob
    ALLIANCE MEMBER

    The pcv has to go to a vacuum source, and since most flathead intakes are two plane, two (normally 1/4" pipe) holes are drilled into the bottom of the intake, one in each plane. This allows all 8 cylinders to act on the pcv. Fittings are installed with 3/8" hoses ( or solid tubing) which are teed together and then connected through hose to the pcv.
     
  19. acme30
    Joined: Jun 13, 2011
    Posts: 203

    acme30
    Member
    from Australia

    Lots of ways to add a hidden PCV - here is one way where the PCV is all within the engine and can't be seen.

    I pinched an idea of a hidden pcv valve from one of the build threads on the HAMB.

    Apologies for not acknowledging the originator of the idea (I can't recall who it was but not me). I followed the monkey see monkey do principle.

    I used a Toyota tarago PCV valve fitted into a core plug which is then fitted into what was previously the downdraft tube then hooked it up with flexible high temp line under the manifold so you won't see it. 8)

    Note you put the shortened downdraft tube back in the original hole in the front of the block. Air comes in the back of the engine via a breather.

    Also I am using an earlier (pre 8ba inlet) so it doesn't have an external downdraft tube

    [​IMG]
     
    Last edited: Apr 1, 2021
    fabricator john likes this.
  20. flatjack
    Joined: Feb 13, 2007
    Posts: 953

    flatjack
    Member

    I don't understand this method. PCV valves can require maintenance and under the intake seems to make that a hassle.
     
  21. the oil soup
    Joined: May 19, 2013
    Posts: 234

    the oil soup
    Member
    from Tucson,AZ

    IIRC some PCV valves must be mounted in a certain orientation to function properly.
     
  22. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,833

    V8 Bob
    ALLIANCE MEMBER

    A 3 (or 4) carb intake gets pretty "busy", and locating the pcv and plumbing under the intake can be a good option. I've never had to change my hidden pcv in 20,000 miles, and I know several others with similar experience.
     
  23. You can always weld a 45 degree bung in your exhaust pipe and run a hose from the breather and let the out flow of exhaust suck out all crankcase pressure. No pressure equals faster rotating mass. Higher rpms and more horse power. But what do I know!
     
  24. ado1930
    Joined: Apr 17, 2020
    Posts: 1

    ado1930

    Hey flatjack, I see it’s been a while since your post but I was wondering if you still have or know where to get one of those vertical breather tubes?
    Thanks
     
  25. solidaxle
    Joined: Jan 6, 2011
    Posts: 592

    solidaxle
    Member
    from Upstate,NY

    Your exhaust would be pushed back through the crankcase. If you have your hand over the end of your exhaust there is pressure. The crankcase pressure would need to be greater then the exhaust pressure to make that work.
     
  26. This method has been used on race cars for many years. You can buy 45 degree bung kits from suppliers like summit and jegs for this exact reason. The bung and nipple are welded pointing towards rear of car not towards engine. The exhaust pressure passing over the nipple creates a vacuum. I believe this method is banned in nascar.
     

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