So I evenly overtorqued the head bolts..questions?

[InFrnt0fU]

So after learning that the torque wrench I was using was older and probably out of calibration, I'm quite sure that I overtorqued(80+ft'lbs) but did so evenly. I'm very sure they are even cause I stopped after each bolt made a bit of a squeak sound(I know thats odd and probably not great). Sorry for the newbie questions, theres just so many little things to worry about.


""Should I just leave it be and go ahead with reassembly and just make sure when I do the retorque after 500 miles I have an accurate torque wrench?""

thx for your time.
x ryan

 

[Piratetip]

What type of lubrication?
Stock head bolts, ARP head bolts or head studs?

 

[InFrnt0fU]

Arps with moly.

What type of lubrication?
Stock head bolts, ARP head bolts or head studs?

 

[jdub]

<Sigh>...Bolts or studs?
And how do you know if it's an over torque or under torque?

 

[Dirgle]

There should be a paper that came with your ARP's that tells you what those bolts are rated for. ARP has been changing the specs on the bolts, so you would need to see what that paper says.

 

[jdub]

Yeah, but the spec is different for bolts vs studs...that's why Piratetip asked. He didn't answer the question. Plus a torque wrench that is out of calibration can under torque just as easy as over.

It doesn't matter I guess...I would re-torque the hardware. ARP recommends that 5 tightening/loosing cycles be done on bolts or studs to get an accurate torque. Backing the hardware off will be doing the same thing.

 

[Dirgle]

Yep, that is why I said he needs to look at the paper, studs or bolts he would at least know what they need to be tightened to. But your right, it wouldn't matter unless he had an accurate torque wrench to use.

Answer: Find out what your hardware recommends for torque, get an accurate torque wrench and re-torque them. That is you best option for peace of mind. Do it right do it once.

 

[ATL88Supra]

mine are 80 may 82 pounds gor 20k miles on it no problems, have not needed to re torq



edit.... ARP bolts stock head gasket

 

[jdub]

Read the thread man...we're not talking about the usual re-torque after 500 miles or so.

And for the record, you might get away with not re-torquing studs after several heat cycles, but you darn sure want to do it with bolts.

 

[Dirgle]

Agreed

 

[Frank Rizzo]

Guys read the 2nd sentence, he said bolt not stud or nut.

That squeak he heard was the ARP washer grinding into the aluminum head. They can only be torqued MAX 75ft/lbs on an aluminum head such as a 7M.

 

[jdub]

Yeah, he did say bolt...I can't count the number of times posters have said the same thing and call a "nut" a "bolt". Just wanted to confirm so the correct spec gets posted....but, like I said, it really doesn't matter...he needs to back them off and torque to the correct spec for either bolts or studs.

The 75 ft/lb limit for ARP bolts is due to the different heat expansion of aluminum vs the steel block. The greater expansion of aluminum when it gets hot puts a "stretch" stress on the bolt. That plus when bolts are torqued, puts a "twist" stress on the bolt shaft....the combination can put the bolt inside the safety margin ARP designed for the yield strength of the bolt.

 

[Frank Rizzo]

Shhhhh!! You are giving away trade secrets.

 

[InFrnt0fU]

Thanks for letting me know what the squeaking was. I'll make sure to evenly back them out today and go get a good torque wrench. Thanks guys.

Shhhhh!! You are giving away trade secrets.

 

[tekdeus]

Hmm, the previous owner of my car said the head bolts/studs have been torqued to 100 ft/lbs.

 

[Shima]

thats a wholeeeee lot a torque

 

[jdub]

Depends on if moly or oil was used and which hardware it was...bolts OR studs (you don't have both).

If moly was used, his hardware was over torqued (a lot!)...ARP torque values are based on 75% of the yield strength. That means there is little left to accommodate the greater expansion of the aluminum head...it's worse for bolts due to what I posted above. If motor oil was used as lube, it's a under torque...the current spec for studs is 120 ft/lbs (was 105 ft/lbs), for bolts its 110 ft/lbs.

This is why guys should read the spec sheet instead of making it up as they go or listening to what their buddies say.