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Max 392 Bore size

Discussion in 'The Hokey Ass Message Board' started by sgunlock, Oct 17, 2010.

  1. the SCROUNGER
    Joined: Nov 17, 2005
    Posts: 518

    the SCROUNGER
    Member
    from USA

    there's a big difference in structure layout design, between a block designed for sleeves, and an old V8 like most of us run that had no sleeves. In an old V8, the original cylinder wall had 2 purposes, it was what the piston ran up and down on, but also held the deck down solid, so heads can be bolted to it. When that original cylinder is cracked, holed, or gets too thin, the heads start to pull up. Look at this repair using sleeve. Look at the head bolt holes in the deck, the one under his thumb. the only thing holding that firm, is the cylinders. Remove the cylinder like that big hole there, and guess what, that deck no longer is solid enough to torque a head down on and hold the gasket. Do this to 2 cylinders side by side, and a large area of deck is weakened. Put 8 sleeves in, you have an expensive boat anchor. There is nothing under those tapped bolt holes but air i.e. water jacket area. The threaded head bolt holes are not part of the block wall casting, but are only part of the deck, being held down by the original cylinder walls.

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    Last edited: May 21, 2012
  2. the SCROUNGER
    Joined: Nov 17, 2005
    Posts: 518

    the SCROUNGER
    Member
    from USA

    when you get done boring a thin wall block for a sleeve, there's almost nothing left of the original cylinder. For all effects and purposes, the only thing holding the sleeve, is the top/bottom of block. Deck integrity is greatly reduced.

    get a couple cylinders sleeved next to each other like this, and when you try to torque down the heads, what it does is pull the deck up at the threaded head bolt hole area of the deck, while the deck between the cylinders stays down- everything starts to flex because the cylinder is not there to hold it in place. Instant blown head gasket, or maybe after a few weeks running it. White smoke out the exhaust. Ooops what happened to my high dollar rebuild/sleeve job ?

    anyone with a lot of sleeving experience will advise, sleeve ever other hole, not next to each other, they know better

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    Last edited: May 21, 2012
  3. the SCROUNGER
    Joined: Nov 17, 2005
    Posts: 518

    the SCROUNGER
    Member
    from USA

    now a block that was designed for sleeves from day one, notice how the meat that contains the head bolt holes, is cast right in to the block not in a thin deck like our old V8's. You can change sleeves on this engine 100 times and it won't affect its integrity.

    it has to be designed for sleeves, otherwise it's a band aid fix

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    Last edited: May 21, 2012
  4. the SCROUNGER
    Joined: Nov 17, 2005
    Posts: 518

    the SCROUNGER
    Member
    from USA

    designed for sleeves from day one, look where the head bolt holes are, and how they are part of the block casting, not part of a thin deck that can move. The bolt holes don't rely on the cylinder walls for support, they are cast into the block wall itself.

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  5. Atwater Mike
    Joined: May 31, 2002
    Posts: 11,625

    Atwater Mike
    Member

    We used to have a 'portable' machine shop service come to our BMW dealership and install sleeves (after a 'Kwik-Way' bore IN THE CAR!) on some 2002s. (that's a 2-door car with a 2-liter 4 banger): quite a few got this 'fix', some of them all 4 cylinders, head removed and crank still in!

    I shuddered every time the tech next to me started tearing a head off. The metal dust would be flying in two hours! LOL
    A BMW store! Outrageous!
     
  6. khead47
    Joined: Mar 29, 2010
    Posts: 1,789

    khead47
    Member

    I have seen some early flathead Ford engines with sleeves in all 8 holes- from the factory.
     
  7. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    I have no problem with sleeves either, and have made SERIOUS power with several holes sleeved. If I wanted to take an engine out to a larger overbore for whatever reason (piston/ring availability for one) if I sonic tested it, and one or two holes were on the thin side and the rest looked good, i wouldn't think twice about sleeving it. I have also been in the situation of scattering an engine and damaging a couple holes in an otherwise good race engine, punched sleeves in those cylinders and put it back together. never had any problems, and if anything, the holes with the sleeves probably sealed better.
     
  8. moparmonkey
    Joined: Aug 14, 2009
    Posts: 565

    moparmonkey
    Member
    from NorCal

    Just to add fuel to the fire...

    I have a 392 block that currently has a bore of ~4.125". Some spots are a bit more with wear, but I suspect its last finished bore was 4.125". It has a ridge at the top of the cylinder, and was owned and run by an old drag racer.

    To be sure, I have NO idea how thick the walls are now other than to know that it will probably need multiple sleeves to continue. But it apparently had no issues running down the 1/4 at .125 over, and the block wasn't filled. Obviously, I don't think that all 392's can do that (the 392 shown below from another thread couldn't), and I'd sonic check before I got anywhere near that much of an overbore. But it can, and has, been done before. Only way to know for sure is to have it sonic checked.

    As far as sleeves are concerned, I'd probably look for a new block before I sleeved all 8, at least right now. I'm holding on to my 4.1" 392, eventually I suspect it will be worth the extra machining costs to fix it. I wouldn't hesitate to sleeve a couple cylinders. But sleeving all 8 has been done before, with a nice build thread right here on the HAMB...

    Whole thread is here-http://www.jalopyjournal.com/forum/showthread.php?t=292239

    But here's the interesting part-

     
    Last edited: May 22, 2012
  9. Dan Timberlake
    Joined: Apr 28, 2010
    Posts: 1,530

    Dan Timberlake
    Member

    Not all engines' head bolts are threaded into bosses that are part of the cylinder wall.
    Figure 25 here
    http://www.studebaker-info.org/SAE/TSVE/tsve.html

    Yes, that detail puts a limit on maximum possible bore size, but probably reduces the need to finish cylinders with a torque plate somewhat.

    It's an SAE paper co-authored by the interesting Studebaker Engineer S Sparrow, from back in the days when the papers were as likely to talk about the problems and mistakes as the glowing successes.
     
  10. TR Waters
    Joined: Nov 18, 2006
    Posts: 1,439

    TR Waters
    Member
    from Vermont
    1. Early Hemi Tech

    "these are highly competent machine shops better than any machine shop you probably ever walked in to up in VERMONT. They own their own dynos, flow benches, sonic testers, shot peeners, etc. One has been in the business around 40 years now."

    all I can say is....... WOW :)
     

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