FE Cylinder Bore

Discussion in 'Engine & Performance' started by davbell22602, Jun 6, 2012.

  1. davbell22602

    davbell22602 67-79 Ford Trucks #1

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    Does anybody know how far out round can FE engine be before it has to bored out? i have 390 thats 3-5 thousands out of round when checking it with a bore gauge. Its currently bored out to 30 over.
     
  2. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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  3. davbell22602

    davbell22602 67-79 Ford Trucks #1

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    That is interesting article. That there block that they are working already 30 over and they honed out to 40 over. I just need to know how out of round can Ford Fe 390 have before having it bored out.
     
  4. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    Sorry still looking for exact specs.
    I'm not much help yet but still looking.

    I'll put in my two cents.

    Well .005 is half way to a .040 from a .030 bored over.
    Consider how much wear has occurred from the original .030 -
    you said like .003 to .005

    Now is that .003 - .005 consistent all the way around or is it
    at the top and bottom of the cylinder? Like an egg shape
    looking down from above.

    If they drove it 100,000 miles and what was worn was .003 - .005
    Seems like a lot of wear to me.

    Still depends of how much oversize from a .030 bored over piston rings
    can fit on a .030 piston. Cast rings vs Moly rings.

    If .035 rings are out there you could hone it to .035
    that would leave .00250 play all the way around the .030 piston.

    I think with the limited new FE parts available you may be stuck with the standard .030
    piston size you already have and new matched rings for .030 or the next step would be a .040 bore and hone then matched piston and ring set in .040.
    There may not be a "half size" ring set @ .035

    I've seen some egg shaped cylinders before and I've seen huge ridges at the top before. Considering those types of wear what kind of wear have the pistons seen?
    Like a measurement of the circumference of all the pistons taken at several points.
     
    Last edited: Jun 6, 2012
  5. ksingltn

    ksingltn Full Access Member

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    I've got a book with the specs in it, however, its a hundred miles away and I won't be home until friday at the earliest. If you still need it then, I'll post what I can find.
     
  6. davbell22602

    davbell22602 67-79 Ford Trucks #1

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    Go by measurements on reading a camping compass.

    N to S and E to W is 5 thousands out. NW to SE and NE to SW is 3-4 thousands out. Its mainly in the middle of the cylinder.
     

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