Over tightened head studs

[ae86 slide]

So I replaced my pistons in my 4agze and put a new HKS 1.6mm metal HG on. I re-used my ARP head studs and torqued it all up on the weekend. I torqued them to ARP specs (60 foot pound) but felt suspicious about the amount of force I was putting on the torque wrench before hearing the 'click'.

On a hunch I went and bought a new torque wrench, set it to 60 ft pound and went over all the nuts, it clicked instantly. Set it to 65, clicked instantly. I have kept going up in increments of 5 ft pound all the way to 80 and it's still clicking straight away, after hitting 80 I threw a tantrum and came inside.

So I'm assuming the process I should take now is loosen the nuts in several sweeps. Remove studs and check for stretch (just measure the length of the stud?). Clean the head gasket, head and block (I used copper spray when installing).

If the studs are ok can I re-use them?
Is it possible to over compress a metal head gasket?

Cheers lads

[Skylar]

Just quickly, there's a difference between static coefficient of friction and kinetic coefficient of friction. It is normal that you will have to apply more than 60 lb.ft of torque to move it again. Whether that number is higher than 80lb.ft, I don't know.

Undoing would be the same as always. Undo from outside in, in several sweeps like you said. Yep. measure length of stud for stretch. Reused studs is fine as long as they're in spec. Hell, you can reuse head bolts even in performance applications.

Why are you going to lift the head off the block? Just remove the studs to check for stretch and torque it back down. You can just loosen it to where clamped down but not pulling down and it'll keep the seal intact. Would rather do that than break the seal and have to clean all the cool stuff off the head gasket and apply the copper spray (which you didn't need to with a coated MHG).

It's a metal headgasket. You are trying to crush solid metal with other much smaller metal. I really doubt it. The head bolts will stretch before that considering the stress applied through the 10 head bolts at ~1cm diam vs like 400cm2 or whatever surface area of the head gasket.

Also, I have 2 torque wrenches. I put a 10mm in-hex drive socket on one torque wrench and a 6 point 10mm socket on the other. Set them to the same setting and have them fight each other. They normally click off at pretty much the same force. I'm satisfied to use them then. Sometimes I'll try another setting too if it's something real sensitive. It's not exactly calibrating but it's better than nothing, and snapping bolts!

[ae86 slide]

Thanks for the reply Ken. The reason I was going to pull the head off and clean everything was I thought that when I released the pressure on the head it may crack the seal of the HG. Thanks for steering me straight. I'll wind them off and re-torque to the desired setting.

Cheers, Jase

[anastasios]

I use one of these torque wrenches (not sure if its the exact model) but i paid about $400

[Skylar]

Yo, before you undo them, do a test on the old torque wrench like I said in my post and see what the "60" really clicks off at. It might be correct for all we know.

[Skylar]

Also, now that I think about it, that stuff on the MHG might not have bonded to the contact surfaces because it hasn't been heat-cycled yet. I dunno for sure but just suggesting. Normal headgaskets however will stick as soon as you apply the slightest amount of bolt tension.

[4A-GE Power]

What sort of metal gasket is it?? You can squash multi-layered steel gaskets a little . You probably already know this but make sure you put a small amount of oil, not too much, on the threads and under the washers, so as to keep it from binding as you are tensioning, as that obviously requires more force to overcome. Head studs are high tensile so they don't tend to stretch unless they are designed to do so, they often just snap instead!! So they will be fine to reuse, and just clean all the surfaces before assembling again with an alcohol of some sort and reapply your copper gasket spray if you want to remove the head.

[4A-GE Power]

Oh and spend the money on a Warren and Brown deflection torque wrench!!! They the shit!!!