HEADBOLTS...at what point do they give?

[suprabad]

Anybody ever strip a headbolt or the threads on the block? I haven't yet but I have to retorque my headbolts (stock toyota) after changing my headgasket (so far so good) and I'm wondering how tight I can torque them. Right now (or at least when I put the motor together) they are at 82lbs. How tight can I go? I have heard alot of people trash talk the stock bolts but mine have held together and I read a metalurgy report that was quite favorable. According to what I read they're not the trash that everyone says they are. Can I replace the headbolts now or would that f-up the new headgasket I just put in? If I can replace them...how is it done and is it worth doing?

 

[RacerXJ220]

Must be that "aight peace" california pride.

 

[mkIIIman089]

So, you reused the stock bolts?

 

[Boostedstr8six]

You won't strip the block or the bolts. Yes the factory headbolts are of good quality. However, the material they are made of has a relatively low yield value. I am quite sure your headbolts are stretched pretty badly since you have them at 82 lbs/ft. :aigo: Your new HG won't last long.

 

[boost fiend]

your best bet is to just order new arp bolts or head stud kit.
worked for me(3 hg in 3 yrs.)

 

[GrimJack]

Stock headbolts are good to at least 72 foot pounds. 82 might be a bit much, but then, I haven't heard of anyone who has had the stock *bolts* fail - it's always a lack of torque making the head gasket fail, not broken or stretched bolts.

That said, ARP hardware is a great idea, they can be torqued to over 100 if you wish.

 

[mkIIIman089]

http://www.ma70.com/bishop92t/destruction.html

Bishop has rounded off a headbolt... however this is one of the very few incidents that I have ever seen a headbolt ever actually fail.

 

[Boostedstr8six]

Overtorqued stock headbolts = bolt deformation(stretch) = less clamping force = BHG

 

[suprabad]

Yes, I reused the stock headbolts. Every one can laugh now. (At least I'm honest.) I wanted to see first hand what the deal with them is. I just retorqued them and they seem to have held pretty well. To me, putting on a new head gasket is not the end of the world. If you know what your doing it can be accomplished in a day. Besides which I like wrenching on the Supra. But I definitely respect your guys imput and experience. I'm sure you guys are right about the ARP bolts and I probably would have used them if I could have got them right away. I'm building a ground up 7mgte and it's gonna be bad-ass (trick crank and rods, forged pistons, monster turbo. huge intercooler, sodium filled valves, fully balanced and blue printed, etc...) and I'll definitely be using ARP fasteners throughout. I was hoping to have it together for Vegas but It doesn't look like it's possible because I'll running a built automatic w/ new electronics and paddle shifters that won't be done in time. I guess I'll have to wait till next year to show it off. I will post pic's as I get ready to put it together.