Oil Pressure Equalization line

Discussion in 'Race 400/430/455' started by Jim Weise, Feb 24, 2015.

  1. gymracer01

    gymracer01 Well-Known Member

    J.W. thanks again for taking time to respond to my post. I guess the thing has me puzzled about this is that the last 3 or 4 engines I have ran in my 2 cars have had stock oiling with some clean up of passages but a stock pump and the pressure when hot is 60 to 65 psi. I run the engines 6000 each shift and 6350 across the line at the 1/4 mile. The current engine in the red car has ran 11 seasons this way on the same set of bearings and rings with stock rods. That is why I upset to lose this engine with all these high dollar mods. But thanks again.

    Jim N.
  2. Jim Weise

    Jim Weise EFI/DIS 482

    Yup, keep the rpm there and the stock oiling with a few mods typically does just fine. Built dozens and dozens of 500-600 HP engines over the years that have just that..

    Good luck with it.
  3. Jim Weise

    Jim Weise EFI/DIS 482

    Very relevant Randal.. I had actually sat in on a discussion about that, back when I as contemplating doing this mod.

    Then TA came out with the lifter bore girdle, and we decided to go that way.

  4. 71GS455N25

    71GS455N25 Silver Level contributor


    Have you ever heard of a case where installing a Oil Pressure Equalization line would damage your front cam bearing? What is your take on the oil pump booster plate (or wear plate as I call it)?
  5. LARRY70GS

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

    Which rod bearings were damaged? If they were at the rear of the block maybe you had a lot of drop off of oil pressure from front to rear. You didn't have a HV/HP oil pump did you? They can hurt the front cam bearing.
  6. Jim Weise

    Jim Weise EFI/DIS 482


    No, I could not see how adding that line would impact the front cam bearing at all.. if anything, reduction in pressure would be easier on it.

    But I don't suspect that 10psi would make that much impact on the forces the front cam bearing is seeing.

  7. 71GS455N25

    71GS455N25 Silver Level contributor

    All rod bearings were worn except the back two but, #7 and #8 got really hot and destroyed the rods! then bearing sparkles got into the dual groove cam bearings and smoked them but did not hurt the lobes! we destroyed the KB C107 cam getting it out :mad:

    It was a oiling issue but i cant figure it out, it made 65lbs of oil pressure.

    Got new eagle rods, new TA C107 cam and back to the drawing board!

    the joys of making hp
  8. 71GS455N25

    71GS455N25 Silver Level contributor

    i used stock oil pump melling gears with a ta modified cover and wear plate
  9. buicksstage1

    buicksstage1 Well-Known Member

    How do I post this as pic?

    Attached Files:

  10. LARRY70GS

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

    I printed it out and scanned it as a jpeg. Then hosted it on photobucket. I'm sure there are other ways, but I'd have to research it.:grin:

  11. Jim Weise

    Jim Weise EFI/DIS 482

  12. Jim Weise

    Jim Weise EFI/DIS 482

    With the snag it grab, it shows up like this


  13. LARRY70GS

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

  14. buicksstage1

    buicksstage1 Well-Known Member

    • I am trying to wrap my head around this statement Jim. The idea that Pressure and volume work hand in hand covers a lot of ground and that is where you can have less pressure and more volume. It takes more pressure on a smaller restriction to get the same volume.

      My Idea and what I can put together on all this oil pressure vs volume stuff it is like the finger over the garden hose theory. If you restrict the hose end the fluid shoots further but if you did a test and filled a bucket with the fluid in a timed event ie: say 30 seconds restricting the fluid by covering 50% of the hole with your finger vs a open uncovered hose the open hose end would fill the bucket faster.

      In order for the restricted hose end to keep up and fill the bucket with the same amount fluid in the same amount of time you would have to increase the feed press over the line that is uncovered so that means the problem we are faced is a balancing act between to much oil pressure to keep up the supply which robs HP, kills distributor gears, cam gears etc etc etc. So we increase the oil P/U size to help eliminate pump cavitation, smooth all turns, then enlarge the oil feed side and remove restrictions in turn making the oil system more efficient by raising the volume but lowering the pressure.

      Oil wants to travel the path of least resistance.

      I found this on a Science web site and was trying to figure out how much of this is the same between oil and gas: Pressure and volume are inversely proportional to each other. This means that as the pressure decreases, the volume increases, and as the pressure increases, the volume decreases. One way to think of this is if you push on a gas by decreasing its volume, it pushes back by increasing its pressure. This relationship is called Boyle’s Law and makes up part of the ideal gas law.
  15. buicksstage1

    buicksstage1 Well-Known Member

  16. Jim Weise

    Jim Weise EFI/DIS 482


    Boyle's law deals strictly with pressure in a vessel/closed system .. and is stated this way:

    The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of gas remain unchanged within a closed system.

    Simply put

    With a given mass of an ideal gas, with constant temps, the bigger vessel you put it in, will decrease the pressure proportionally.

    10lbs of Argon in a 125 Cubic Foot tank , will be twice the pressure of that same 10lbs of Argon, in a 250CF tank.

    Not sure how your relating this to gas, or liquid, flow rates.

    Your correct in your previous statement that with a given orifice size, (your thumb over the hose) to increase flow rates, you have to increase pressure, which is what I stated previously.

    You seem to agree with that, so I am not sure what your confused about.

  17. buicksstage1

    buicksstage1 Well-Known Member

    Hence why I said" I found this on a Science web site and was trying to figure out how much of this is the same between oil and gas"
  18. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Liquids and gases are both fluids and follow fluid dynamic laws/theories. Liquids tend to 'react and normalize' quicker because they are mostly incompressible, and they behave slightly differently because of density, liquids obviously being more dense and have more inertia and no open space, etc.

    You want an volume versus pressure cluster F in an engine oiling system, go look at one of these Pontiac OHC L6 engines I'm using. The lash adjuster was a re-engineered flat tappet lifter, which had too large a surface area so standard oil pressure's ran would put tremendous pressure on the cam follower and eat the cam**. So a restrictor tube, with an orifice hole was used to reduce the pressure to stay below ~15psi, however over the range of oil pressure from idle to ~6,500rpm, it would still over pressure, so the Pontiac engineers stuck at 30psi relief spring in oil pump. They were balancing having enough pressure to keep the lash adjusters pressured up versus the volume needed to keep them full, and I'm guessing above ~30psi there was no happy medium to balance pressure and flow. During rebuilds, people would remove them, or stick a higher relief pressure spring in the pump and promptly destroy the cam. I guess at "only" ~205-230HP running 30psi oil pressure at 6,500rpm was acceptable.


    The restrictor tube.

    The lash adjuster.


    **Modern OHC engines that use the same lash design have "lifter" bodies that are half the size of these Pontiac ones, so can run full "normal" engine oil pressures without putting excess pressure on the cam.

    [/Non-Buick Hi-jack]
  19. Dave Mongeon

    Dave Mongeon Well-Known Member

    from our experience the oil system problems/ solutions came in rpm steps
    others may or may not agree with the solutions but this is how we saw it and dealt with it.
    1st problem we had was from idle on up! Cam bearings! We would kill them in 5 minutes. cam bearing changes , front cover and block mods along with not using the HV pump have pretty much eliminated this problem.
    2nd std oil system to 6500 RPM problems usually showed up in #7 rod first all std block and front cover mods make this quite reliable up to 6500 without balance tube. 75-80psi
    3rd step around 7000rpm std system started to show problems again added balance tube and scavenger type cover opened up clearances 100 psi (some cases hv pump again
    4th step around 7500rpm problem moved to #3 rod priority oil system (jim has good description of what was involved to prep stock block for this in old post thank god/Mike for
    aluminum!) , dry sump all made 75-7600rpm quite reliable.
    5th step 7800 up 135 PSI prey to Buick Gods (or dial it back to 7500 and just watch Scotty run lol)

  20. 71GS455N25

    71GS455N25 Silver Level contributor

    Great advise Dave!

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