Main Bearing Feed Passage Oil Restrictions

Discussion in 'Street/strip 400/430/455' started by Bluzilla, Oct 16, 2016.

  1. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    No, all the mains are fed off the passenger side lifter galley. The line feeds oil to the rear of the galley but the galley is fed from the front as well. Once pressure comes up, it equalizes along the entire galley. Without the line, you would see a difference of pressure at the front and rear of the engine, the line equalizes the two. That is my understanding of it.
     
  2. Bluzilla

    Bluzilla a.k.a. "THE DOCTOR"

    Larry's explanation is correct. It's the same principle as using a fuel log to supply a stable amount of pressure and volume of fuel to dual feed or multiple carburetors. If you look a few posts back at the photo of my old engine you will see that I probably should have been using a log to my Dominator, ....especially since my system incorporates a return line at the regulator.

    Larry
     
  3. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    Ahhh yeah me comprende now. Since the port or sending unit tap is on the supply side the pump just fills the void (balance line), the oil meets ware it meets along the passenger side lifter galley , and on down the mains.

    Can we go over the distributer gear oiler , or composite dist gear next
     
  4. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    And the 1/2 inch balance line is the size to provide enough oil to create the balance.
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Anson, read Jim's description of the Bypass line from his oil mods thread. Obviously, there are different ways to accomplish this.



    Bypass line


    Bypass line

    Purpose: To equalize the pressure at the front and rear of the main galley.

    Background: Back in the late 80's, when Mike Bucy and I first got together on to go drag racing, we were sitting around in his garage one winter day, and examining the oil system of our 455.. we had problems with hurting the number 7 rod bearing, it always looked more worn than the other ones. I surmised that it may be due to oil pressure dropping off at the end of the block. Now the factory combated this problem, by necking down the passenger side main galley, to maintain pressure at the rear of the block, but in applications where the engine regularly sees rpm in excess of 6000, and additional oil feed to the rear of the passenger galley, is beneficial.

    When to do: Any engine that will see serious duty, above 6000 rpm. Those are serious street/strip /drag race only motors, that produce their power up at those levels.

    Tools required :

    • 1/4" NPT tap
    • 7/8 drill bit

    Supplies required:

    Various -6 A/N stainless fittings, brass street elbow, as pictured.

    While I did not make this modification in our subject block here, I do have pictures that I will show, of previous motors done this way. The trick here is to keep the line in the bell housing, below the plane of the casting, to insure adequate line to flex plate/flywheel clearance. You typically must re-tap the hole in the block to allow your street elbow to be fully seated, for the best clearance.

    While there are a few different ways to do this, I prefer this line routing, as it allows for the use of any Starter Motor, and well as provides a balanced oil pressure gauge pickup point, at the back of the engine.

    Here are some pictures.

    [​IMG]

    You pick your oil up at the factory sender hole.. in this case it was tee'ed to allow for the feed for the Vortec Supercharger oil feed. The line then runs down the passenger valve cover, to the rear.

    [​IMG]

    We then turn it at the back of the engine, with a 90* hose end, and use a pressure adapter there, for the connection to the second line, that leads to the rear of the block.. I drill a hole the LH bell housing, and feed the completed line thru that hole.

    This is the fitting you will use at the rear of the passenger side galley.

    [​IMG]
     
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Now that mod can bleed off some oil pressure. It isn't needed unless you are running the bigger oil pump gears, which most know is a no-no, and unnecessary.
     
  7. Jim Weise

    Jim Weise EFI/DIS 482

    We actually did do that testing Anson, and the results were similar to what your talking about.

    We found that with the bypass line, the entire system pressure dropped slightly, about 9psi as I recall. This is due to a removal of the restriction of just the front feed, and a sure indicator that we are actually flowing oil thru the line and feeding the rear of the engine.

    We monitored oil pressure front and rear, with the dyno's pressure sensors.. with no balance line, the rear oil pressure was 9 psi lower on average than the front, thru the pull..

    When we added the balance line, I suspected it would bring the oil pressure up to the front reading, but it actually dropped it to the rear one.. and once I thought about it, it makes sense. We are near the limits of the output of the stock pump, a lesson that hit home when I started building the Tomahawks. To maintain or increase pressure, we must have sufficient volume to supply to it. Now the difference was like 80psi to 72 or something like that at 6000 rpm, so it was not a real worry, but it was an indicator that the stock geared pump was near it's limit.

    This was on a street strip motor similar to Larry's.

    Oil systems is general are a balance of restriction vs flow, the trick is to strike the right balance between the two.


    I think even -6 line is overkill when used as a balance line, if one really wanted to hide it, I believe you could use a 5/16 steel line, and achieve the same results. No data to support that, just a gut feeling.

    JW
     
  8. Bluzilla

    Bluzilla a.k.a. "THE DOCTOR"

    Balance lines are nothing new, ... the high rpm Ford Cleveland guys have been using that line system since the early 70's. Though I believe that they feel installing restricted lifter bore bushings and cam bearings is more effective for their engines (which oil the lifters and cam bearings first also). Too bad the BBB's lifter bores are so thin walled to begin with.
    Once again I feel maintaining as close to an equal ID of 1/2" throughout the balance line and lifter galley (opening the rear galley from 7/16" to 1/2") can only help maintain a closer "balance" of pressure and volume to the main feeds.
    Looks as though my original post has gone off into a different direction.
    Maybe a separate post/thread pertaining to the seemingly controversial balance line as well as it's orchestration would be useful, ..... then again there may already be one started. :cool:

    Larry
     
    Last edited: Aug 5, 2017
  9. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    Also we need to look at ware we are taking the pressure for the rear. From what i see its being tee'ed off the balance line before the entrance to the rear galley. To be accurate you would need to first tap the plug with a sensor, record your psi. then do the balance line with the tee reading, pressure should be someware between the two. With a 1/2 in line volume increased to the rear but at an overall loss in psi. 72psi at 6000 rpm is fine, As long as you can have 15 to 20 psi at idle your fine. I would be willing to bet that with a 1/2 inch balance line your actually lowering pressure to the driver side somewhat. A 3/8 id. line would seem a better balance between the pumps limits and psi, and necessary volume. 5/16 id line looks good too. Probably just going by the size of the rear main feed in the block is all that is necessary, which is the main target of the whole deal.
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Anson, I believe you are so over thinking this.

    Larry, I remembered that thread and looked it up,

    http://www.v8buick.com/index.php?threads/oil-pressure-equalization-line.293955/

    I bring it back up to the 1st page. It is in the Race 400-430-455 Forum
     
  11. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    i have printed out the JW oil mod threads. Geting the size of the balance line rite the first time , thats my goal.
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  13. Bluzilla

    Bluzilla a.k.a. "THE DOCTOR"

    Ok, ..... I'll try to explain this one last time to make it easier to understand. Once the restrictions are relieved behind the cam bearings as in my original start of this thread, what you end up with is #2,3,4, & 5, main feeds all 5/16" each. That's 5/16" X 4. Now add #1 main feed and tell me that "1" 5/16" line to the rear is going to supply the volume of roughly half the total main feeds, .... I don't think so.

    There should be no pressure loss at all with a 1/2" line running to rear VS a -6 or 5/16" line ... as that size dictates more available volume and is sized accordingly to the front modifications done.

    What should be looked into also is the restrictions behind the lifters in the right galley, ... especially in the necked down area starting just behind #3 main bulkhead and running to the rear of the block.

    Larry
     
    Last edited: Aug 5, 2017
  14. Bluzilla

    Bluzilla a.k.a. "THE DOCTOR"

  15. I have the oil balance line assy from this supercharged motor if somebody wants it cheap.

     
  16. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    Thanks Larry"s
    I went to all the links and read all the posts, JW dyno info showed that the psi dropped 6 psi with the 6 or 1/2 in balance line. But it was still at a livable psi. The final thing to do would be to tear apart bottom end after however long you want to run it, and see how #5 compares. Which is totally impractical to most of us. So which is better a higher volume at a lower pressure, or s higher pressure at a lower volume. The only wAy to increase volume and pressure is the longer oil pump gears,which is problematic. For a motor that would rarely see 6000 rpm it's probably not necessary. A 1/2 in balance line is diverting more oil than is needed .
     
  17. Bluzilla

    Bluzilla a.k.a. "THE DOCTOR"

    Bottom Line: My engines will all run 1/2" lines, though my RPM will be higher than yours. I'm sure if you decide to use a balance line for your application a small line will be fine.

    Good Luck!

    Larry
     
  18. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    Hey Doc, and Wizard,
    and others,
    I appreciate all your input and time you put into it.
    regards
     

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