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Arrrrggggggh Cracks!

Discussion in 'The Hokey Ass Message Board' started by Merlin, Apr 19, 2005.

  1. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    I picked up a flatty 8 this weekend and upon tearing it down i noticed several cracks,They're from the stud bolt hole to the water jacket between the cylinders in three spots. A friend who helped me tear it down said this was normal with flatheads, Is it normal? Can these be fixed?
     
  2. Hotrob
    Joined: Mar 23, 2005
    Posts: 589

    Hotrob
    Member
    from DFW, TX

    I know that some can be fixed, but I think it depends on where they are.
    I am pretty sure that you are o.k. as long as they do not involve the valve seat.
    Don't quote me on that, but I think there is hope.
     
  3. TINGLER
    Joined: Nov 6, 2002
    Posts: 3,410

    TINGLER

    From what I understand, its a RARE flathead thats NOT cracked.
     
  4. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    All three are in between the cylinders from the stud bolt hole to the water passage just underneath. They don't come near the valves or the cylinders.
     
  5. Brooding Swede
    Joined: Feb 5, 2003
    Posts: 406

    Brooding Swede
    Member

    Just "about" every flathead has cracks.. it only matters how many and big they are. cracks are normal. if you do a good job with the rebuild you should be ok. also post some pics of the cracks. 3 out off the 4 flathead i had, had cracks. Have some who knows about them take a good look at them and then judge it..good luck.bs
     
  6. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    I'll try to get some pics of them this weekend(have to get batteries for camera) and post them. They're not big cracks but are noticable.
     
  7. Deuce Rails
    Joined: Feb 1, 2002
    Posts: 2,016

    Deuce Rails
    Member

    Definitely post some pics.

    If you have that many cracks, it may be cheaper to find a better block than to have the cracks repaired.
     
  8. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    Ok don't laugh at my rendering but since i don't have batteries for the camera yet here it goes.
     
  9. Petejoe
    Joined: Nov 27, 2002
    Posts: 12,539

    Petejoe
    Member
    from Zoar, Ohio

    You rendering did the job.
    Both of the flattys I have had and some others I have seen have these same cracks. No big deal. As long as the exhaust and intake areas dont have cracks running from one to another and there is no compromise in the valve and cylinder area your ok. Now hurry up and get that thing together so we can see it.:D
     
  10. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    Aye Aye Captain!:D
     
  11. Ichoptop
    Joined: Mar 5, 2001
    Posts: 721

    Ichoptop
    Member

    just use a good sealer when you put any head bolts in to the waterjackets and they will seal up fine, copper coating on the gaskets will do the rest.
     
  12. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    Will high temp gasket sealer do?
     
  13. BillyB
    Joined: Mar 11, 2004
    Posts: 35

    BillyB
    Member

    Mervin - Use aviation permatex on the head bolts. Stays soft and seals well.
    Bill
     
  14. hey magic boy [aka merlin] where in fla are you:? and welcome missed your intro.
     
  15. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    Thanks i'm in Tampa! Home of the crazy mixed up drivers.
     
  16. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    Those aren't cracks, they're stress relievers...
    Av Permatex or the gray non-hardening modern stuff Permatex has for fasteners into water--can't think of name. Forget smearing goo on antique gaskets, you can now get modern ones with the teflon or whatever mystery magic stuff, just like you'd use on a modern engine. Should help allow the heads and block to do their things as they expand and contract more happily.
    Studs: Do not tap holes, although it is quite likely they have been tapped by someone in the past 50 years--the block threads are extra-deep class three fit, and tapping with any normal tap or thread chaser will remove metal and leave studs very slightly wobbly--I always wondered about this as I happily ruined those holes in the past.
    Before final assembly, screw in studs just a little more than finger tight, mebbe 10 ftlbs, with your chosen goo on the threads, put on heads and gaskets, and tighten the nuts on to tight enough to force nuts square against heads but not enough to compress gasgets, and allow to set for a while. Assuming head surfaces and nut bearing surfaces are machined square to the world, this will help set the studs vertical so you don't have a struggle getting heads on and off.
     
  17. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    Thanks for the info Bruce! Glad ya posted that cause i was going to tap all the threads before it went to my machinist.
     
  18. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    Just cleanemout with gun cleaning brushes and carb spray, and tell the machinest to stay outta there too. Banjo rear axle bolts and holes are special, too--run a tap in there, and all the lube will soon be on the outside of the case.
     
  19. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    Got plenty of gun cleaning brushes! lol Thanks again for the info!
     
  20. Glad it is OK, I never really checked it before it went to One-eye.
     
  21. sonnyb
    Joined: Apr 6, 2005
    Posts: 18

    sonnyb
    Member
    from n.c.

    :) i ,ve heard the same as the other guys...as long as the crack does not run into the valve seat od down into the cylinders it will propably be ok.. you might want to put a stud in the particular hole and use sealer on it before installing the heads..
     
  22. Deuce Rails
    Joined: Feb 1, 2002
    Posts: 2,016

    Deuce Rails
    Member

    That's good! :)
     
  23. Oilcan Harry
    Joined: Mar 3, 2001
    Posts: 906

    Oilcan Harry
    Member
    from INDY

    Those cracks are so common they have a factory part number. Cracks from bolt holes to water holes can be ignored. Cracks down a cylinder can often be fixed and the cylinder sleeved. Cracks in the pan rail or main webs are terminal.
     
  24. 296 V8
    Joined: Sep 17, 2003
    Posts: 4,666

    296 V8
    BANNED
    from Nor~Cal

    One of the first thing you should do after its relatively clean is presser check the water jackets. Its kinda rare but there can be cracks in hard to see places, like the exhaust ports.

    On the last one I did I had about 8 or 10 studs leaking water with Teflon thread sealer:mad: . I tore it back down and used permatex right stuff and it sealed up perfect, zero leaks.:)
     
  25. FiddyFour
    Joined: Dec 31, 2004
    Posts: 9,024

    FiddyFour
    Member

    Oilcan Harry hit it on the head...

    here is what i get from my readin'

    the center main web between the babbit and the main bearing area is a common crack place... NO FIXUM for that. gotcha a boat anchor. same on the pan mating surface.

    cracks around the jackets are common and so are jug cracks and valve/cylinder cracks... those can all usually be fixed. worst case have it sleeved and haul ass :D
     
  26. 51 MERC-CT
    Joined: Apr 5, 2005
    Posts: 1,594

    51 MERC-CT
    Member

  27. Merlin
    Joined: Apr 9, 2005
    Posts: 2,545

    Merlin
    Member
    from Inman, SC

    So far those are the only cracks! I have to find the tool to get the valves out so i can get it cleaned and inspect it real good.
     

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