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Thread: SBC Engine Bearing wear help.

  1. #1
    Senior Member RACING JUNKIE
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    SBC Engine Bearing wear help.

    Can someone help me figure out what happened here. Eagle rotating assembly, show 1.5 thou on all rods and mains. Engine has 500 miles on it. It showed great oil pressure until it got warm ,160* or after 20 mins of diving. Then oil pressure dropped to 10-20 lbs. THe bearings show to be starving for oil, correct, especially the three center main caps? I thought the front oil galley plugs could have been leaking, which would have blead off oil pressure as soon as the 20/50 got warm, but they look fine.

    383 sbc roller hyd cam.
    Wix oil filter
    Castroil 20-50
    Engine was built with assembly lube and i primed the engine before installation.

    The problem was not that the engine was dirty or contaminated.
    I cleaned the block flawlessly, installed cam bearings and re cleand. All oil plugs where removed.


    I tried it with a melling stock pump first, drove 100 miles and changed to hv pump, same problem?

    Thanks for any help!!!!!!





  2. #2
    Senior Member RACING JUNKIE
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    I found the problem, front center oil galley plug is leaking internally. I will post a video if i get time.

  3. #3

  4. #4
    Senior Member RACING JUNKIE
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    Glad you found the problem, screw in plugs are the way to go.

    My buddy had a similar issue with his BBC that he built, might have been the same problem plug leaking or something who knows it's gone now.
    But anyways, he had all new lunati H beams, Eagle forged crank, new pistons, pressure was low after warm up, around 15/20 idle, didnt last long 2 passes later it spun a couple rod bearings and snapped 2 of them H beam rods like they were tooth picks. :shock:


    I tried to check your video out, didnt work for me.


    Cp
    ***IN GOD WE TRUST***

  5. #5
    Senior Member RACING JUNKIE
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    Yes i agree, i knew all my clearances where good and i was loosing oil pressure some where. The three plugs went in nice and tight, i dissasembled the engine and taped them for 1/4 pipe plugs tonight. I imagine this problem happens to alot of people and never now the problem!!!

  6. #6
    Senior Member RACING JUNKIE
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    All the small blocks I've ever seen and or ran (not many) had threaded pipe plugs in that spot anyway, glad you caught before.....
    ***IN GOD WE TRUST***

  7. #7
    Senior Member RACING JUNKIE
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    Glad you figured it out. Have you measured that crank in the middle and the ends of each journal? It looks like the journals are hourglass shaped.....Just my opinion but I'd want closer to .003 on the rods and .0035 on the mains.

  8. #8
    Senior Member EXPERT BUILDER
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    Here is a good site for this...

    http://www.heavydutyenginekits.com/bearing/

  9. #9
    Senior Member RACING JUNKIE TheYellaBrick's Avatar
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    Now THAT is a 'teachable moment'
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    to those who
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  10. #10
    Senior Member RACING JUNKIE
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    Quote Originally Posted by DrivingMissDD
    Now THAT is a 'teachable moment'
    x2. Even if you primed the engine with the cover off, the timing gear and chain would hide the problem.
    Good catch!

    Dave
    Dave
    http://www.racingjunk.com/profile/343797
    "All that is necessary for the triump of evil is for good men to do nothing" Edmund Burke


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