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Thread: Main bearings small block chevy,rocket block

  1. #1

    Main bearings small block chevy,rocket block

    Hi I have a 427 olds rocket block chevy engine that keeps tearing up #2& 4 main bearings after 2 burnouts. I have had the block line honed,a callies crank at first, had it turn twice due to bearing failure & just put a eagle crank in it with the same results. New four stage drysump oil pump & line also.All the rest of the bearings are ok. Any ideas would be great.

  2. #2
    Senior Member EXPERT BUILDER
    Join Date
    Jul 2005
    Location
    Wylie,Texas
    Posts
    276
    How long have you had this engine? What is the stroke, bore and deck height, fuel system and fuel, and any other info you have. I had a 463 with a olds rocket block, dry sump, injected on alcohol and also had main bearing problems. Mine was a 4.250 stroke with a 6.030 aluminum rod. top side of rod bearings would be a little hammered but never into the copper. Tell me what you can and we will go from there! Thanks,Don

  3. #3
    Hi It has a 4.125 bore, 4 inch stroke,6.125 GRP alum rods,9.325 deck. It is alchol injected. I have a 5 spd lenco trans. The rod bearing seem to be ok but not much run time to tell. Rons twin terminators.New motor never made to the track. Made ten dyno pulls with no problems.
    Thanks Mike

  4. #4
    Senior Member EXPERT BUILDER
    Join Date
    Jul 2005
    Location
    Wylie,Texas
    Posts
    276
    What is the new motor and how much power dit it make? Mine only had 1 Terminator on it and could not get the egts above 1000 degrees. What are your incremential times. I bet with a 5 speed its realy fast!

  5. #5
    427 small block ,it made 750 hp @ 7500 .It is in a2800 pound 69 camaro 8.90@ 160.Had same combination in my last motor with no main bearing problems but kept losing #3 rod so i got a new block.I shift it at 8000 rpm.Would like to get it back on the track this year.

  6. #6
    Senior Member EXPERT BUILDER
    Join Date
    Jul 2005
    Location
    Wylie,Texas
    Posts
    276
    200 runs is the most i ever got before i lost #4 main bearing. I always managed to catch it by looking at the screen filters in the oil pan. Bad thing about a dry sump you lose a main bearing but oil pressure still at 80 lbs. Good luck with the new block!

  7. #7
    Senior Member MASTER BUILDER
    Join Date
    Jul 2006
    Posts
    184
    Could be lack of oil return holes to the bottom. Those blocks don't have much for oil drain back holes. Could be pumping the oil pan dry, with not enough time to drain back. I have seen this before with those blocks. Otherwise, there should be no issue. Those are a dry sump or wet sump block, so, if you run it wet, you need to add some extra drain back holes in the lifter valley. They do that, so, when you dry sump it, you can keep the oil where you want it.


    Frank
    Advanced Performance
    www.get-ap.com

  8. #8
    Junior Member SHOW GUEST
    Join Date
    Jun 2005
    Location
    Minnesota
    Posts
    4
    How many oil resrictors? On my wet sump setup I needed to put four total in the galleys to control oil flow to the lifters and such. If you want more details I can provide them.

    Dart has since updated the new Iron Eagle blocks to easily restrict the hole.

  9. #9
    Member MASTER JOURNEYMAN
    Join Date
    Mar 2006
    Posts
    37
    pwmax is correct..i have a rocket block and the oil drain back holes are way to small...i lost some bearing in 2 passes so we put screens in between the cam bearings in the lifter galley...problem solved

  10. #10
    My block is a dry sump


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