Headbolts

Discussion in 'Heads and Cylinders' started by Flathead, Dec 29, 2015.

  1. Flathead

    Flathead New Member

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    If I have no tools with gauges is oversnugg OK for head bolts?
     
  2. 2door

    2door Moderator

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    That all depends on your experience with fasteners. "Snug" to you might mean one thing and something different to someone else. As I've said here many times, over tightening fasteners has caused more problems than any other one thing with these kits. In the case of the cylinder head too loose or too tight can cause you further problems.

    Trying to 'guess' about proper torque is not a good idea. I'd check around and try to find someone who will either loan you a torque wrench or tighten the fasteners for you. The problem with having someone do it for you is you'll need to go back to them after a few heat/cool cycles and have the torque 'checked' a couple of times after the initial tightening.

    Save a few bucks and buy a torque wrench. It'll be cheaper than the repairs you might have to make by not using one.

    Tom
     
  3. ZipTie

    ZipTie New Member

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    I'm a newbie to these engine kits also, but common sense says...Better to be bit too loose than too tight. If you don't get the torque wrench then air on safety and hold the wrench near the bolt so you have less leverage and snug them up that way.
     
  4. sbest

    sbest New Member

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    Too loose ends up like this:
    [​IMG]
    Blown head gasket.

    Too tight means head studs stripped out of the case. ARGH!

    A torque wrench is a great investment, much cheaper than broken stuff.

    Steve
     
  5. allen standley

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  6. crassius

    crassius Active Member

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    failure in the head studs most often is caused by the acorn nut binding on the threads - if you are using open nuts, then you will be a bit safer if you can't get a torque wrench to do it right

    less common, is the threads of the stud pulling out of the cylinder, I always loosen the studs a bit & reseat them to be sure the threads seem to be performing correctly and weren't left loose or cross threaded at the factory
     
  7. buba

    buba New Member

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    Cylinder stud -case metal sucks what is a non helicoil fix when a head gets lose and compression firing causes a stud to strip in case???--Anyone??? success stories???
     
  8. crassius

    crassius Active Member

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    haven't done it on HTs, but always used to drill large to put in brass bolt - cut it flat to the surface & file area smooth - drill it to take proper size threads

    was successful on motorcycle cases, heads, & cylinders all thru the 50s & 60s, as brass has very similar expansion to aluminum

    amount of hand work makes replacement cheaper tho if you're paying for that labor
     
  9. ezrider

    ezrider New Member

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    [​IMG]

    What kind of specific socket size....and length does one use to get at these piston head bolt caps ??


    _
     
  10. mogollonmonster

    mogollonmonster New Member

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    Either 12-14mm, I believe the Dax motor I'm running is 14mm. Standard sockets are deep enough, although an extension might be necessary to clear the cooling fins. I always use 1/4 inch drive, to keep me from being over zealous. I don't own a torque wrench, but I'm one of them who can "feel" torque, I've been turning wrenches a long time, and I'm familiar with the sensations of steel preparing to give. There is no fastener on these engines that needs to be that tight. I do not always torque wrench, but when I do, I use the needle type.

    Buy one, it'll save your bacon. Most of my repairs are done on the roadside, well away from anyone and anything, crosslegged on the shoulder of some lonely highway. Those situations are rarely conducive to proper equipment usage. After making a head gasket out of a bud lite can with a razor knife, just get the thing tight and get it home. That is not the proper way of things, buy a torque wrench.
     
  11. Slogger

    Slogger New Member

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    I tighten them to a half a tug past snug. <about 15 foot pounds>
    I don't even have a head gasket, never did.


    I never mess with them til the engine is cool. The aluminum threads will strip easier when hot.
     
  12. ezrider

    ezrider New Member

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    I'll just have to specify a 'deep socket' which should work. Supposedly, the head bolts are already factory tightened, and you don't have to fool with them. However, its never a bad idea to check those head bolts along with all the other fasteners just to play it safe.
     
  13. sbest

    sbest New Member

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    Compression firing never strips the threads on these engines. It is always human error. If it was running well while you had it, it wasn't likely the previous owner. The case metal on these is not so bad either, but some of the owners....

    If you have a 48cc motor with M6 studs, you can always drill and tap them out to M8. Room for the nuts will be a bit tight but 12mm x M8 nuts are available. If you have the 66cc with the M8 studs I don't think you are going to get M10 in there. Not a lot of metal around the stud for an insert nut. Pretty much gotta use a helicoil.

    As for what tool to use, the M6 nuts are pretty much always 10mm and due to the depth you have to use a socket. The M8 studs have 12, 13 and 14 nuts available. 13mm is ISO standard, 12mm is Japan standard and my Grubee came with 14mm, go figure. I carry a short "tube wrench" for on the road repairs:
    [​IMG]

    Stripped threads on these motors are pretty much always operator error. You have to use a torque wrench at least for the first 5 years of your motor mechanic existence. I use one in all the critical areas still.

    Steve
     
  14. mogollonmonster

    mogollonmonster New Member

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    Compression stripping at less than 180psi... Nope. Operator error. It might be aluminum but it ain't a pie tin. Blame the dog, but not compression.
     

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