a few questions on bearings

Discussion in 'Oil and Lube Systems' started by Grumpy, Mar 26, 2018.

  1. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member


    90% or more of the pictures were and are posted by other people on the internet , and merely used to illustrate, yes ideally a finish journal should be as close to mirror finished and glass smooth as you can get it, but level, from end to end except for the curved machined bevel,on each end ,its diameter concentric and even in its dimensions its intended and ideally standard size or standard under size, is critical


    its always a good idea to verify machine work, theres always some machine shops that either do low quality or shoddy work, and you can,t expect an engine to operate correctly if the clearances or consistency of the bearing and lubrication surfaces are not correctly set, you would not bet the first or last guy to be told a crank was cut to a size that was not the true size or sold the wrong bearings for an application, you should always verify machine work, with both a precision measuring tool and plasti-gauge
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    MEASURE CAREFULLY
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    http://garage.grumpysperformance.com/index.php?threads/can-i-get-it-polished.9214/

    http://garage.grumpysperformance.co...guess-on-clearances-and-journal-surface.9955/

    http://garage.grumpysperformance.com/index.php?threads/bearing-clearances.2726/

    http://garage.grumpysperformance.co...tion-of-crank-durring-short-blk-assembly.852/

    http://garage.grumpysperformance.com/index.php?threads/rotating-assembly-bearings.9527/



    no I have always found it best too assemble an engine after placing it on a decent engine stand
    if your going to assemble an engine you should buy or rent a decent engine stand, and a few basic tools

    http://garage.grumpysperformance.co...g-with-a-local-machine-shop.14419/#post-74383

    http://garage.grumpysperformance.co...haft-journal-surface-finnish.2728/#post-72043


    http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-68850
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    the oil groove terminates before it gets to the bearing parting line. This style of main bearing has accounted for a 15 percent or more increase in hot idle oil pressure. So if you're looking to eliminate some of those unexplained low oil pressure gremlins contact your bearing manufacturer and ask about this style bearing and availability for the engine applications that you are building.

    keep in mind only the upper main bearing shell should have an oil groove, having a 360 degree oil groove lowers the bearing ability to handle high rpm loads

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    THESE BEARINGS PICTURED ABOVE, with the full 360 degree grooves,LOOK GREAT BUT HAVE LOWER LOAD CAPACITY
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    a 180 degree bearing has only the upper in the block grooved to improve oil flow,a 270 degree has the oil feed groove extend further 45 degrees on each lower bearing shell

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    MAIN BEARINGS WITH 360 degree oil grooves
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  2. Loves302Chevy

    Loves302Chevy "One test is worth a thousand expert opinions."

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    the oil groove terminates before it gets to the bearing parting line. This style of main
    bearing has accounted for a 15 percent or more increase in hot idle oil pressure.

    I really like this idea.
     
  3. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    I am set in my ways Like Grumpy is in his own ways.

    He Like s Clevite H Bearings.
    I Like The Clevite P Bearings or Better Yet Vintage Vandervell Bearings.

    No one in the Pontiac World ever reports How Long their engines last like they used to.
    The Federal Mogul 3/4 Groove Bearings were used by many for a while.

    All Large Journal Pontiacs 421, 428, & 455 used 1/2 Main Bearings.
    Factory Cross drilled Cranks.

    The Low Po Pontiac V8's used fully Grooved mains & non cross drilled cranks.

    I have torn apart 389's & they used 1/2 Grooved Bearings with a Non cross drilled crank.
    The opposite of what your supposed to do.
    But apperantley Pontiac deemed it a non issue.
    Crank Journals Mint like new 40+ years later.

    #5 main is always fully grooved in all Pontiacs.

    I like 1/2 grooved bearings myself.
     
  4. Loves302Chevy

    Loves302Chevy "One test is worth a thousand expert opinions."

    I wonder if that design would not throw enough oil on the cylinder walls at idle?
     
  5. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    the oil flow from the upper engine,heads, valve train flowing down and being constantly thrown around,
    by a spinning rotating crank,rod, pistons along with the oil spraying from the edges of the rod and main bearings,
    assure the lower cylinder walls are constantly bathed in a monsoon of oil mist.
    as rpms increase so dose the oil pressure and as a result the volume of oil flowing past the bearing clearances.
    thats enough oil that there are separate lower oil scraper rings on all pistons to limit the oil reaching the upper compression rings.


    http://garage.grumpysperformance.com/index.php?threads/basic-info-on-your-v8-lube-system.52/

    http://garage.grumpysperformance.com/index.php?threads/bearings-and-oil-flow.150/



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  6. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    The connecting Rod side clearance plays a large roll in lubricating the cylinder walls & wrist pins.
    The SD421 Pontiac used the most connecting rod side clearance per pair of rods on each crank throw.

    The early 1959 Pontiac 389 I have has the Forged Rods.
    Also has machined in oil spurt holes.
    Seen that when I had the oil pan down.

    Connecting rod material is large factor in what the engineers decided to use for Rod side clearance per pair.

    The more side clearance the more oil throwoff to the cylinder walls & wrist pins.

    Interesting trying to figure out why the engineers chose what they did.
     

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