OIL PUMP....high volume, high pressure?
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OIL PUMP....high volume, high pressure?

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    Member DOZZR's Avatar
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    Default OIL PUMP....high volume, high pressure?

    I just had the bottom end of my olds redone (twice), I am pretty sure the machinest didnt allow for "looser" clearances, and I spun a bearing 5 minutes into the test run. The pressure never dropped (40-75)until I idled it down to do a basic check for leaks ect. (up to this point I was jazzed !!!!, all the vitals were perfect and it ran GREAT! ) when I shut it down, I smelled burnt oil and the pressure dropped to almost zero. I towed it in and tore it down, all but a few of the rods and mains were toast
    So i didn't go back to the same builder, The shop I went to this time has alot of experience with the marine olds motors, lucky for me I shut it down before any damage was seriously done, he ended up mic'ing it/polished the crank, straightlined it, and re-size the rods, I took It out sunday and it ran and did great, but when I shut it down the oil pressure at idle dropped from 40 psi (cold) to 20 (warmed up) at idle, and would jump right back up to 50-60 psi when I accelerated.
    I have a standard oil pump in it, and now rather than see what happens I am going to change it out. Mellings has two different pumps one is high "volume", the other high "pressure". Summits description of the "pressure" pump mentions for looser tollerences, but the "volume" pump, would have been my logical choice. I have already installed 2 drainback lines one each side for the oil return from the heads to the pan (hardlined),enlarged and matched the oil drainback passages from the heads into the block, polished the valley, de-burred any obstructions so hopefully the oil can get back to the pan quick enough.
    So my question is ......wich pump should I go with, the high pressure or high volume ?
    Thanks,
    John

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    ... Some Kind Of Monster's Avatar
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    Quote Originally Posted by DOZZR View Post
    I just had the bottom end of my olds redone (twice), I am pretty sure the machinest didnt allow for "looser" clearances, and I spun a bearing 5 minutes into the test run. The pressure never dropped (40-75)until I idled it down to do a basic check for leaks ect. (up to this point I was jazzed !!!!, all the vitals were perfect and it ran GREAT! ) when I shut it down, I smelled burnt oil and the pressure dropped to almost zero. I towed it in and tore it down, all but a few of the rods and mains were toast
    So i didn't go back to the same builder, The shop I went to this time has alot of experience with the marine olds motors, lucky for me I shut it down before any damage was seriously done, he ended up mic'ing it/polished the crank, straightlined it, and re-size the rods, I took It out sunday and it ran and did great, but when I shut it down the oil pressure at idle dropped from 40 psi (cold) to 20 (warmed up) at idle, and would jump right back up to 50-60 psi when I accelerated.
    I have a standard oil pump in it, and now rather than see what happens I am going to change it out. Mellings has two different pumps one is high "volume", the other high "pressure". Summits description of the "pressure" pump mentions for looser tollerences, but the "volume" pump, would have been my logical choice. I have already installed 2 drainback lines one each side for the oil return from the heads to the pan (hardlined),enlarged and matched the oil drainback passages from the heads into the block, polished the valley, de-burred any obstructions so hopefully the oil can get back to the pan quick enough.
    So my question is ......wich pump should I go with, the high pressure or high volume ?
    Thanks,
    John
    Never never never never go with a high volume pump in an Olds for a marine application. The deal with Olds is they pump all the oil to the top end too quickly and run out of oil in the pan and it runs out of pressure. There are a few mods you can do to an Olds that are almost necessary to make them work right in a boat. The drainback lines are a good first step. Do a search, I’m sure someone will post a link soon.
    Last edited by Some Kind Of Monster; 06-17-2008 at 02:41 PM.

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    mo balls than $cents$ IMPATIENT 1's Avatar
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    mondello(sp?) restricted pushrods would be a smart upgrade bout now pull the pump back off the motor and shim the bypass spring till you have a oil pressure you're comfortable with

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    I'm No Expert Shaun's Avatar
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    Unless you where standing on it and drained the pan in that 5 minute test you where going to have problems regardless if it was in a boat or car.

    Hi vol pumps i always read were for motors setup with larger clearances, with the extra clearance the motors flows more oil, the hi vol pump keeps the system full/pressurized.

    Hi Pres pumps i dont really know anything about, i would like to learn more about them though. In my head right now i'm thinking maybe hi pres pumps are really for motors cranking out serious amounts of hp to help keep the rod and crank from tagging the bearings? This is my THEORY

    How big is your pan btw?

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    B.A.M aka "Black Azz Mike 396_Ways_To_Spit's Avatar
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    High pressure is needed BUT high volume is NOT needed in an olds application. Get a set of restricted pushrods or just install pipe cleaners(chep fix) in your old ones.
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    www.highflowdynamics.com LakesOnly's Avatar
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    Every Olds 455 engine that comes through the shop with a rod kicked out of the pan has at least one thing in common: half-grooved main bearings. Every time.

    Every Olds 455 engine that leaves the shop as a fresh rebuild has at least one thing in common: fully-grooved main bearings. We have zero Olds 455 come backs and we contribute this to the the fully-grooved main bearings.

    LO
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    This post © Copyright 2007-2020 Paul Kane. No copying, linking, printing or otherwise without express written permission.

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    Quote Originally Posted by LakesOnly View Post
    Every Olds 455 engine that leaves the shop as a fresh rebuild has at least one thing in common: fully-grooved main bearings. We have zero Olds 455 come backs and we contribute this to the the fully-grooved main bearings.

    LO



    Band Aid!!

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    Member DOZZR's Avatar
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    I will give yo a quick rundown on what I have done to date, first I detailed the valley and opened up the drainback holes in the heads and if you look right under the top right head bolt hole, a section af the block is ground back (follow the head gasket line, where the hump is, that actually used to be just a hole for the oil drainback)

    Here is how it normally looks

    Then the return lines


    I also had the guys drill smaller holes in the cam bearings prior to installation as my oil restrictors (sorry didnt get a chance to get pics of them.
    I am not sure what other mods I can do but I thank you all for the input, I am going to pickup a new high pressure pump, and take it from there.
    Thanks again for the tips.

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    Quote Originally Posted by DOZZR View Post
    I am not sure what other mods I can do but I thank you all for the input, I am going to pickup a new high pressure pump, and take it from there.
    Thanks again for the tips.
    Just to give you a hard time bud...... YOU CAN BUY A CHEVY MOTOR!
    Sure does look pretty on the stand. I'll have my old cell phone back tomorrow night...I'll call you.

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    Quote Originally Posted by Some Kind Of Monster View Post
    Never never never never go with a high volume pump in an Olds for a marine application.
    Smart advice.

    There is nothing wrong with 20PSI hot idle oil pressure and 50-60PSI revved oil pressure.
    Stock oil pump here too.

    My 454 runs that going on 4 years now.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
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    The rest of us are being dragged along kicking and screaming.

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    Quote Originally Posted by DOZZR View Post
    I took It out sunday and it ran and did great, but when I shut it down the oil pressure at idle dropped from 40 psi (cold) to 20 (warmed up) at idle, and would jump right back up to 50-60 psi when I accelerated.

    So my question is ......wich pump should I go with, the high pressure or high volume ?
    Thanks,
    John
    First of all, the pressures you quote sound pretty normal, the warm oil will flow better than the cold and therefore the lower pressure at idle. I believe the rule of thumb is 10 psi for every thousand RPM.

    If you put in a high pressure pump and run the same type oil, you will likely see the same pressure at idle, and a higher pressure at speed. Basically a high pressure pump has a stiffer regulator spring so the pressure bypass in the pump won't open until the higher pressure. At idle, the pressure bypass in the pump is closed and you pressure is a result of wt and type of oil, the bearing clearances and engine speed.

    If you want to boost the idle oil pressure, try different wt oil, try synthetic oil, etc.

    Just my $.o2

    Doug

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    I just bought a Melling oil pump (M-77) and I believe it to be a standard pressure and volume pump. It did come with a spring that you could use to increase pressure if you desire. I stayed with the stock spring. I believe less is more when it comes to oil pumps. Why have the extra strain on the cam gear when it is not necessary?

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    Quote Originally Posted by Warp Speed View Post


    Band Aid!!
    Since when is running a much better designed part in place of a poorly designed one considered a band aid?

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    Nice looking engine. I think I would change that Fram oil filter to a NAPA Gold. Just my .02 worth.

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