TTY Head bolt final torque question
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TECH Junkie
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From: Minneapolis, MN
TTY Head bolt final torque question Ok, long story short I was putting a head on my LQ4 tonight and having the old man help me. I am using the factory head bolts and following the procedure properly when on a couple of the head bolts my dad let his hands slip on the angle guage while holding it for me and I am fearful that some bolts may be off. At any rate, I know the factory TTY specs, but what do those specs equate to be in final torque? 110 ft lbs? More less? Someone know what the factory head bolts finally end up being for total torque?
Thanks in advance-
Thanks in advance-
TECH Resident
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From: South Alabama
Because they are TTY bolts, its very difficult to define a torque, hence is why they give you a torque, then a degree. The operation is designed to take the bolt into the plastic range of deformation, just beyond the range of 0.2% elasticity. This causes the bolt to have a one time higher clamping force to hold the heads down. Its a one time deal as the next time (if you were to re-use the bolts) you tighten them down they will be further into the plastic range of deformation and have even less clamping force as the material at this point is approaching failure (Mechanics of Materials).
Cliff Notes: You cannot define this required force as a torque value, period.
If you want more than you'd ever want to read, put "0.2% elasticity" or
"plastic deformation" into google and read till yer hearts desire.
Cliff Notes: You cannot define this required force as a torque value, period.
If you want more than you'd ever want to read, put "0.2% elasticity" or
"plastic deformation" into google and read till yer hearts desire.
Last edited by Weezzer; Jul 31, 2008 at 11:30 PM.
As stated above, there is no clear answer. Your options are to leave it alone or re-do it. If you don't think the angle is off by much, leave it alone and keep an ey out for leaks, etc.. If you have no idea of the final angle, then buy a new bolt set and re-do the head.
Do you have a tq wrench? If so check on of the bolts that you KNOW that torqued correctly by seeing where it was torqued to. I always tq them to 75-80lbft. Most of the time we use ARP but there are a few that go back to factory. Never had any problems, I torque them to 30, 50, final 75
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TECH Junkie
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Do you have a tq wrench? If so check on of the bolts that you KNOW that torqued correctly by seeing where it was torqued to. I always tq them to 75-80lbft. Most of the time we use ARP but there are a few that go back to factory. Never had any problems, I torque them to 30, 50, final 75
What I was going to do is go to the first head bolt that I know is perfect and carefully keep adding torque to the wrench and let it click, then tighten the wrench some more, let it click and hopefully come to a point where once the bolt starts to barely move the wrench would "click" Meaning I would work my way up to a "click" that would make a perfectly good head bolt move like a 1/16 of a turn. Then apply that same clickable torque setting to the rest of the bolts as a last run
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Verdad Gallardo Don't use a torque wrench, either leave them alone or replace them. What you are measuring are two different things, static and dynamic friction, which will vary all over the place unless you lubed them when they went in which I doubt. TTY and torque are two completely different methods of setting bolt stretch and preload, don't mix them.
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TECH Junkie
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Don't use a torque wrench, either leave them alone or replace them. What you are measuring are two different things, static and dynamic friction, which will vary all over the place unless you lubed them when they went in which I doubt. TTY and torque are two completely different methods of setting bolt stretch and preload, don't mix them.
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From: Bergen County, NJ
If you are confident they are only off by about +- 10* then leave everything alone - they'll be fine and the less you muck with them the better. If you are not confident, take the time now to replace them all and do it over.
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TECH Junkie
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Eh I'll just leave the damn things alone then. I am probably just being overly ****. My dad only slipped his grip on the angle guage on 2 head bolts and I know whch ones they are. Also I doubt 10 degrees is enough error to cause a leak anyways. If it leaks a bit I'll just sinch 'em down. Thanks all for the info
Like already stated, I'd leave them alone if they are only off by a little bit. Unless you plan on spraying a large shot of nitrous or running boost, you should be fine.
