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Flathead oil return line

Discussion in 'The Hokey Ass Message Board' started by 348_altered_bantam, Apr 16, 2013.

  1. 348_altered_bantam
    Joined: Jun 16, 2010
    Posts: 11

    348_altered_bantam
    Member
    from St-honoré

    Hi,

    there is no return line on my oilpan (flathead 1941) and it's all freshly painted! :(

    I want to know if I can drill my intake near the gaz pump to return the oil from my Beehive??

    I found a dipstick with the return oil but I prefer the first option if its works.

    Thank for your help.
     
  2. Hi mate, don't know how much this will help but its an old pic i saved a while back..
     

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  3. Dale Fairfax
    Joined: Jan 10, 2006
    Posts: 2,585

    Dale Fairfax
    Member Emeritus

    Your Beehive is a "byp***" filter where only a portion of the pressurized oil is fed thru the filter-in fact there must be a restriction at the inlet to maintain pressure. Once thru the filter, the oil drains by gravity back into the pan (or the valley if you wish.) The diagram posted by 28A is for a "partial full flow system" wherein the full output of the oil pump is filtered and fed back into the engine under pressure. This system requires modifications which should be done only when the engine is apart and can be thoroughly cleaned to remove any chips that might contaminate the oil p***ages.
     
  4. 348_altered_bantam
    Joined: Jun 16, 2010
    Posts: 11

    348_altered_bantam
    Member
    from St-honoré

    OK, so there is no problem to drill the intake to be "in the valley", but its by gravity so it needs to have a minimum slope I guess?

    For the restriction, I took the original fitting from a ford 1946 pan. It looks tho have a smaller hole than the other one...

    That restriction should be before or after the filter? the fitting I'm talking was mounted on the pan.

    28A thanks! but I dont have the "full flow" set up! I just dont have the return hole in my pan and wondering where can I reurn the oil!
     
  5. Dale Fairfax
    Joined: Jan 10, 2006
    Posts: 2,585

    Dale Fairfax
    Member Emeritus

    The restriction must be in the feed to the oil filter. I'm unaware of any restriction (nor of its value) in the gravity return line. I'm not reading your"original fitting from a 1946 pan". That should be the unrestricted return.
     
  6. flathead jack
    Joined: Aug 3, 2012
    Posts: 15

    flathead jack
    Member

    there should be a plug in the block a filter on a flathead is useless just change the oil alot all it is is a hole in the system
     
  7. alchemy
    Joined: Sep 27, 2002
    Posts: 22,782

    alchemy
    Member

    If you don't mind pulling the pan off the engine, that little dipstick tube mount with the oil return boss built in is an easy fix. I used it on a '40 Merc engine.
     
  8. hotrodderhaag
    Joined: Jan 22, 2007
    Posts: 2,146

    hotrodderhaag
    Member

    i looked into doing this with my 37' flathead, but im runnign a supercharger that requires an oil supply and gravity return,, i just dont fell comfortable with the stock pump being able to handle the volume ti the charger, the bee hive filter, and the rest of the engine. correct me if i am wrong.
    thanks!
     
  9. Andy
    Joined: Nov 17, 2002
    Posts: 5,391

    Andy
    Member

    Drilling the intake would work just fine.
     
    Last edited: Apr 16, 2013
  10. 348_altered_bantam
    Joined: Jun 16, 2010
    Posts: 11

    348_altered_bantam
    Member
    from St-honoré

    Thanks everyone,

    What about the orifice? 0.060"....I also saw 0.040" on another post.

    does the original FORD set up have one??
     
  11. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    Volume should be fine for that stack of parts unless bearings are shot...
    Restriction must be on the FEED side of the byp*** filter...OUT has to flow better than IN, or engine oil pressure will blow out the lid gasket!
    You can plug with drilled and tapped screw in your inlet fitting or just solder it up and drill a suitable hole if you don't have the right fitting...hole is somewhere around .060.
    Up into the early forties the filter was optional...dipstick boss with return hole I think there is indeed a fitting, just adapting the invert flare line to the boss) became standard when filters started going on all cars (there's a hint on their usefulness, by the way).
    Kits for the filter as an acessory came in tow flavors...they first sold a special bolt replacing one on fuel pump stand b*** with p***ge through and a fitting to adapt the line. This was dropped...flatheads do NOT like anything adding oil into valley, even in small amounts. They moved to a similar setup feeding into front cover at one of those bolts.
    Bolt with no real machine shop: Find a drill press. Clamp on a block of wood, drill a hole that is snug on your bolt. Drop bolt into hole (this puts it right in line with drill), prevent rotation with a vise grip, and bore right through the bolt endways. You want a cheap bolt for easy working...this is not a stressful location anyhow. Next, see if you can drill a larger divot into head of bolt deep enough to catch a thread or two of a 1/8 pip tap, tin your adaptor fitting, tin your bolt, gronk them together and apply heat and solder. Custom bolt!
    The byp*** is a significantly finer filter than a full flow...add in a PCV if you can to prevent sludge, let the filter chew on any grit.
    If starting from scratch I suspect ultimate filtering would be what they do on big, expensive engines...full flow supplemented by a byp***! Block can easily be drilled to copy the Ford full flow setup used in WWII.
     
  12. 348_altered_bantam
    Joined: Jun 16, 2010
    Posts: 11

    348_altered_bantam
    Member
    from St-honoré

    Thanks Bruce,

    I think I'll go with the dipstick boss with return hole in it (parts number 59A-6751)...that will be easier.

    I saw on Mcmaster-carr good NPT orifice fitting for around 9$.
     
  13. alchemy
    Joined: Sep 27, 2002
    Posts: 22,782

    alchemy
    Member

    Why? Wouldn't having an opportunity for oil to drip over the lifters and cam be a good thing?
     
  14. nutter_street_rodder
    Joined: Sep 16, 2011
    Posts: 107

    nutter_street_rodder
    Member
    from Nevis MN

    I have a Fram flexible tube ***embly on mine. It is marked part number L-26-F, for use on Ford oil & motor cleaner 01A-18658-A1.
    It uses a hollow bolt that replaces the left fuel pump mounting bolt. Also included was a flexible braided hose with a banjo fitting to go from the filter to the fule pump stand bolt. Similar to to how the new disc brake line stuff is made.

    Fram also sold a replacement for this to send the oil back by using the hollow bolt in the distributor mount. It was p/n 01A-18683. I don't know why they made a change? Maybe oil leakage at stand/intake gasket problems?
     
  15. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    I've never run into the problem myself, but anyone who has left out a baffle or vent tube in a flathead reports oil burning...apparently they do not like any extra oil introduced there, which is odd because the valley is an oil storm no matter what. I have heard, again not do***ented, that the change from the FP stand bolt to didtributor bolt for engines predating factory filter boss was made because of oil burning when oil was dumped into valley! Can't prove it and don't want to experiment...use all the baffles!
     

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