pitted bearings... why?

Discussion in 'PSI Superchargers Tech Questions' started by wildman, Feb 22, 2011.

  1. wildman

    wildman Member

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    I tore down my blown BBC yesterday for the standard bearing check. Once again, my bearings are pitted like someone took a screwdriver to them. Why is this happening? I have a system 1 filter and I see no trace of any material at all in filter.
     
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  2. nmro2114

    nmro2114 Member

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    what type of ignition system do you have? What bearing are you using?
     
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  3. SoDak

    SoDak Active Member

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    Explain your engine, how much boost, RPM, are you drag racing, how many runs on bearings, etc?
     
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  4. Mike Canter

    Mike Canter Top Dragster
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    Wjat bearings are you using? Are they triple layer bearings or solid babbit like a Clevite V or M?

    Do you have an oil filter? If so what kind and where in the oil loop is it located?
     
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  5. ITS IN MY BLOOD

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    This is assuming you run Alcohol,....
    Either its residule alcohol that sits on the bearings for periods of time between running your car from the diluted oil in the motor, and you run it that way all year,..???? Its always best for diagnosing the problem,so..how often did you actually change the oil,..no insinuation, just the facts. almost a delimanition, spotting ptted look to it.

    Or maybe you got the bad batch of bearings from,.what was it 97 or 99..???
    Whats the numbers on the bearings...????


    :(
     
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  6. SoDak

    SoDak Active Member

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    pictures would be helpful
     
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  7. Mike Canter

    Mike Canter Top Dragster
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    As said pictures would be great but what would be better if the person that put the original post would answer the questions. Why make a post if you are not going to follow up on it:mad:.
     
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  8. Scouder

    Scouder New Member

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    I know in my case sometimes my day doesn't follow a real convenient schedule. Maybe the guy is stuck at work or something. (Kinda like I am right now) :p

    -Brian
     
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  9. wildman

    wildman Member

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    Stuck at work... yes.... stuck working at home.... yes... :) Anyway here are some answers:

    Ignition: msd 7al
    King race bearings
    filter: system 1 in stock location using wet sump pump
    fuel: methanol
    boost: 25#
    rpm: 8k (or 9400 when I forgot to put in the rev chip)
    #of runs on bearings: 70? I don't have my records in front of me
    #of oil changes: every other outing... or so. Oil looked good so I did not change it a lot.
    more info: Oil. Lucas 70.
    0.005 clearance
    80 to 100 psi pressure
     
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  10. SoDak

    SoDak Active Member

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    Are these rod or main bearings? Which ones, IE #2 main?

    Do the main caps show frett marks indicating they are walking?
     
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  11. Mike Canter

    Mike Canter Top Dragster
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    Wait a minute. You are saying you have about 70 runs on those bearings?????????:confused:

    If then you have nothing wrong with those bearings;). Just check them and change them more often. What worries me even more is that you are saying you have about 70 runs on your rod as well:(.

    If so you are living on borrowed time. Even on a nitrous car we only went 50 runs on the rods and changed pr checked the bearings after every race weekend.

    Lets put it in perspective here. Most alcohol FCs check the bearings after each run and get anywhere from 15-20 runs out of the rods. A promod will check the bearings at the end of each race day and will get 15-20 runs out of the rods. You should be at least checking your bearings a lot more often and when you see them starting to go then change them right away.
     
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  12. Comax Racing

    Comax Racing Member

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    Bearings

    I was also concerned about the 70 weight oil, seems a little heavy for a Chevy on the milder side. Plus the 7AL ignition, could it be detonating and pounding on the bearings?
    I think Mike hit it on the head though, 70 is lots of runs on a single set of bearings.


    My 2 cents
    Corey
     
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  13. SoDak

    SoDak Active Member

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    I'll agree with Mike on the fact that you should be happy with 70 runs on your bearings.
    I was laughed at also when I was talking about 70+ runs on some of my stuff. There are some real differences and I find it very important to clarify when giving opinions, such as, are you running 8000 RPM like Wildman or 10,000 like others. Since what the rod feels is not linear, but yet squared, it makes a difference. Also is it a heavy hemi piston or a light chevy piston, also makes a difference. Is the guy running max on the edge or low boost, low RPM and its pig rich, it makes a difference.

    I feel keeping this type of info in context while we write our opinion answers is important.
     
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  14. Nathan Sitko - 625 TAD/TAFC

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    I would agree with Corey, straight 70 oil is too heavy in my opinion. We were running straight 70 with our TAFC, and it made the bearings look TERRIBLE, even after one or two runs. Switched to a mixture of 70 and 50, problem went away. If Lucas had a 60 weight oil I would have been running that instead, although we did not have any issues running the 50/70 mixture.
     
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  15. ITS IN MY BLOOD

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    I can undertstand the 70 runs,..its a chevy, and no fun to drop the pan.

    And I run Royale purple nitro 60 wt BBC .
     
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  16. secondwindracing

    secondwindracing top alcohol

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    get a hemi then....:p
     
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  17. Dave Germain

    Dave Germain New Member

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    yep

    I second Dave's idea. Get a hemi. Or take it to jiffy lube. I take my Honda there and get a coupon for a free carwash. Dave Germain
     
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  18. smblkbob

    smblkbob Member

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    I run 70 wt with small block chevy. King Bearings, .0055 on mains, fully grooved mains and big side clearance on rods. Works perfect for me running blown nitro. 120lb pressure using Titan Pro pump.

    However, at the end of each race we ALWAYS find 1 or 2 bearings that just don't look quite right and changing them just makes sense. Cheap insurance.

    King bearings seem to have a different look when wearing than I've seen with Clevite. Like acid spots for lack of a better description. Never any debris type marks.

    70 runs? No way. lol

    Bob
     
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  19. SoDak

    SoDak Active Member

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    How much HP do you think you're making and fast do you turn it?
     
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  20. Relentless

    Relentless www.bretitanium.com

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    70 is very brave.

    We might do 20 tops in a season but change rods every season

    As for bearings, depending on how hard we run, either every other run or after every event.

    Just see no point in not changing them for the cost of an engine
     
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