Reading 1512m Bearings

Discussion in 'PSI Superchargers Tech Questions' started by Force Fed, Sep 30, 2007.

  1. Force Fed

    Force Fed Member

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    How much upper bearing squash is acceptable on 1512m shells?
    After 15 1/4mile runs Iam seeing the upper bearings squashing .018"-.022" on all rods. (KB OLDS whipple combo.)
    I was thinking of putting 1512v shells in it, and putting .002" more fuel in every port nozzel.

    Alan
     
    #1
    Force Fed, Sep 30, 2007
  2. ITS IN MY BLOOD

    ITS IN MY BLOOD TAFC

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    Those are definatly hammerd,..iF I WAS YOU
    I would put a new set in,..make a pass,..pull pan
    and bearings and remic them,..any sqaush more than
    say .002 on a single pass would dictate it needs more fuel
    or less timing.....
     
    #2
    ITS IN MY BLOOD, Sep 30, 2007
  3. Bob Meyer

    Bob Meyer Comp Eliminator

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    Alan; with that kind of luck going for you, run out and buy lotto tickets quick!
    (unless that's a typo, and you meant .0018- .0022):)
     
    #3
    Bob Meyer, Sep 30, 2007
  4. Randy G.

    Randy G. Top Alcohol

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    After 15 runs that's only .001 to .0015 per run. They should have been changed out 7-8 runs ago even so.
     
    #4
    Randy G., Sep 30, 2007
  5. nitrohawk

    nitrohawk New Member

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    Bearing Squash question???

    Is there anyone out there that scrapes the squashed material from the side of the bearing and atually uses a ball end mike and measures the thickness of the bearing to determine wear? It might supprise you to find how little actual wear there is to the bearing.
     
    #5
    nitrohawk, Oct 1, 2007
  6. Nathan Sitko - 625 TAD/TAFC

    Nathan Sitko - 625 TAD/TAFC TAD / TAFC

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    Back when we ran a whipple 2-3 thou was acceptable on the 'M' bearings per run if we were running it real hard. If it's more than 1 thou, we'd change it.

    That all being said, we haven't run the 'M' bearings for 4 or so years now, we went to the 'V' bearings and they have saved our butts a couple times.
     
    #6
    Nathan Sitko - 625 TAD/TAFC, Oct 1, 2007
  7. Nitro Madness

    Nitro Madness Super Comp

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    Hey Nitrohawk - we use a tubing mic - it's better than a ball end - has a barrel shaped anvil - does not dig into the soft bearing like the ball anvil - just a tip I got from Dave Hough - Nanook AA/FA
     
    #7
    Nitro Madness, Oct 1, 2007
  8. Force Fed

    Force Fed Member

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    I measured the thickness of the shell and found it was .001" under in the load area.

    When measuring the bearings, I measured the rolled out part on the shell.
    Is this the correct way to measure them or do you remove the rolled part first?
     
    #8
    Force Fed, Oct 1, 2007
  9. ITS IN MY BLOOD

    ITS IN MY BLOOD TAFC

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    That would be called the babbit,.
    and yes, scrape the babbit and then mic them.
     
    #9
    ITS IN MY BLOOD, Oct 1, 2007
  10. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    8/2000

    NOTE TO ANYONE RUNNING M BEARINGS:

    make damn sure you check the date. any m bearing with a mfg date of 8/2000 will almost certainly lead to major problems.

    most of those are out of circulation by now, but it's important to know.

    the reason why most are going away from the m bearings is they are more likely to delaminate due to the softer material. with an extremely rich set up when i was getting my license, i had two rod bearings that nearly came apart. put v bearings in with the same nozzles, same rich setup and no problems.

    as noted in this thread, many people make the mistake of measuring the bearing before scraping the rolled babbit off the sides. the common standard in blown alky applications is no more than .005 squash after being scraped.

    another important measurement to watch is end to end clearance, especially with the harder v bearings. if you start to hit v bearings more than a few thousandths, you have problems. both types of bearings will show wear by measuring the end to end clearance. the end to end clearance should not be below 2.500. my standard is that if a bearing is any less than 2.497 or so, chunk it. 2.497 to 2.502 or so, placing two thumbs in the bottom of the bearing, applying slight pressure to the outsides, you can gain some more clearance. just a little bit of pressure will get the wanted gain. this measurement/methodology was taught to me by tom conway. if the bearing gets too small on the end to end clearance, it will be more prone to spin. this is a measurement of not only what the tuneup is doing, but on the lifespan of the bearing. even if you have a safe tuneup, after 'x' runs the bearing will lose it's end to end clearance, and it's time to pull it out of the rotation.

    an old bearing will also be overly black on the back. that's another visual check of how old a bearing is.
     
    #10
    Will Hanna, Oct 2, 2007
  11. sdpm

    sdpm New Member

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    What actually does cause the back side of the brg to turn black?
     
    #11
    sdpm, Oct 2, 2007
  12. oldskooldigger

    oldskooldigger Member

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    One cause is the galvanic reaction of dis-similar metals.....i.e. aluminum and steel. Add in some oil diluted with alky and nitro for an electrolyte and you've made yourself a nice little battery.
     
    #12
    oldskooldigger, Oct 3, 2007

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