Question about headbolts

[notmymk3]

Well I was a dumass and used the same headbolts when I put the head back on after a BHG job

Question: Can I replace the original headbolts with ARP headbolts fair and simple ?

 

[supramacist]

Yes and the sooner the better.

 

[jdub]

The problem is when you take the old head bolts out, the clamping force is released and that can affect the HG seal.

Before you removed your old HG, what torque was on the head bolts?

 

[supramacist]

Sorry guys. I just assumed he would know to do them 1 at a time.

 

[Sl1dewaysSupra]

I also have a quick question. I know that with head studs you have to re-torque them after a few heat cycles, is it the same with head bolts?

 

[jdub]

Sorry guys. I just assumed he would know to do them 1 at a time.

Yeah, if he wants to replace them, one at a time is about the only way to go. Might not have to though...depends on the previous torque on the bolts. Toyota bolts don't tolerate stretch in terms of retaining bolt strength as well as ARP.

I also have a quick question. I know that with head studs you have to re-torque them after a few heat cycles, is it the same with head bolts?

It's actually the opposite...you always want to re-torque ARP bolts, new or used. With studs, you only have to re-torque if they are new. Once studs go through a few heat cycles during a 1st time use and are reused on a later HG install, a re-torque is not required.

I always re-torque (even with studs) for the peace of mind. Having said that, I've never seen studs that loosened up...bolts yes...studs never.

 

[supramacist]

very interesting

 

[Finnon]

i was always taught to never remove 1 stud at a time as it was very bad.

 

[lazarous]

So it is actually recommended that you replace them one at a time?
I thought that this would warp things, even if you replace them in the torquing sequence.
I heard that to make it so you don't have to retighten the studs you can install them, torque them down to a spec 10lbs more than what you need, wait a little while, loosen them, and then retorque them down. This effectively streches them making them stronger.

 

[jdub]

That's actually that's the problem...neither way is good. Take all the bolts out and you risk compromising the HG seal. Do them one at a time and you risk warping the head. Of the two choices (on a cold head), the warpage issue is the least risk IMO...after all, guys have gone in to do a re-torque when they buy a Mk III and discover a bolt is loose. Tighten it up and have no problem...at least for a while.

What you're referring to is the stretch method vs. the torque method of tightening head bolts. The stretch method requires a stretch measurement tool or gauge...something very few people have. The correct way to get accurate torque readings is to use lube and make multiple series of torque to spec, loosen, torque to spec...ARP recommends five passes. Using moly lube drops the torque required because moly is more "slippery" and is much better at overcoming the friction coefficient of the threads. For ARP head bolts the torque spec is 75 ft/lbs due to the heat expansion properties of the aluminum head on a steel block. Take a look at this:
http://www.arp-bolts.com/Tech/TechInstall.html

What I'm hoping is the Toyota bolts he used were previously torqued to stock specs. On this installation, he should have went no more than 75 ft/lbs. If this is the case, the Toyota bolts were stretched a bit more than previous and should have sufficient strength/clamping force to hold. A re-torque is all that is necessary.

 

[supramacist]

Alright there Jdub. I thought all I needed was a torqe wrench for this and run it and park it. Check it the next morning, and retourqe. Run it fairly again and retorque. Again I think the retorque should be done when everything is cold but I'm also an idiot about some of this stuff and need guidance. I should have went to the motor pool instead of supply and accounting. So how far off am I really. Thanks guys.

 

[jdub]

You're not that far off

What you are doing by torquing to spec, loosening, torquing, etc for the five passes is overcoming the friction coefficient of the threads for the most accurate torque reading. There is no need to heat cycle the engine in between passes...this is just to get the most accurate torque. Actually using a stretch gauge is the most accurate, but I hate to think about how much one of those cost

Don't confuse this with a re-torque of the bolts done later after 5 or so engine heat cycles. The thermal expansion of the aluminum head on a steel block can loosen the bolts a tiny amount...hence the need for a re-torque.

The moly allows you to use the lower of ARP's spec for the bolts...it's better at overcoming thread friction. Keep in mind the spec is for 75 ft/lbs for an aluminum head using moly. ARP does not publish a head bolt spec for using motor oil on aluminum and does not have a spec at all for the use of studs on aluminum either. In the case of studs, I use the 81 ft/lb spec with moly and call it a day.

 

[supramacist]

I'm sorry but it sounds like all I need to is a torque wrench for the first five day's of driving with repetetive oil changes.

I'm switching from pennzoil 10w40 to castrol 10w40
It seems like blasphemy to not run castrol. But maybe that's my gran turismo talking.

 

[jdub]

I'm sorry but it sounds like all I need to is a torque wrench for the first five day's of driving with repetetive oil changes.

Hey...I'm sure that will work just as well. The only thing is the hassle pulling the valve covers off every day

To me, the five passes is over kill. When I built my new motor I did 3 passes to torque the studs, let the car get about 500 miles on it, changed the oil and re-torqued the head studs. Just technique...there's more than one way to skin a cat.

I'm switching from pennzoil 10w40 to castrol 10w40
It seems like blasphemy to not run castrol. But maybe that's my gran turismo talking.

If this is a new motor, run straight Valvoline 30W in it for the 1st 500 miles, change oil & filter (Wix is good), put the same 30W in it for another 1500 miles, change oil & filter again, and switch to synthetic. This way your rings will seat properly. A lot of guys will do a couple of fairly short, hard runs (> 4000 rpm) right off the bat to help the rings seat. During break-in vary the rpm...don't go long periods at steady rpm.

Might want to think about the oil...10W-40 is a bit heavy for a new motor. The German Castrol 0W-30 is very good (a true synthetic)...you can get it at Autozone. It says "European Formula" on the front and "Made in Germany" on the back. Without going into it, this weight oil flows very well...getting good oil flow on engine start is what keeps the wear down. It's a bit "thick" for a 30W...at operating temp it's actually closer to a 40W viscosity wise. You want oil flow, not necessarily pressure to keep your motor happy.

JetJock did this write-up on MkIII Tech:
http://www.mkiiitech.com/forums/viewtopic.php?t=898

 

[notmymk3]

aww crap yeah I dont remember the torque it was at before i removed them but when i reused the headbolts i torqued them down to 65ft lbs

So I take it I should just retorque the original bolts to 75ft lbs and not bother replacing them with ARP bolts

 

[steven89]

aww crap yeah I dont remember the torque it was at before i removed them but when i reused the headbolts i torqued them down to 65ft lbs

So I take it I should just retorque the original bolts to 75ft lbs and not bother replacing them with ARP bolts

Wondering the same thing on what to retorque em to, might be buying a turbo supra that just had a HG change with same old bolts.

 

[jdub]

aww crap yeah I dont remember the torque it was at before i removed them but when i reused the headbolts i torqued them down to 65ft lbs

So I take it I should just retorque the original bolts to 75ft lbs and not bother replacing them with ARP bolts

Probably at 58 ft/lbs (stock) unless you re-torqued before you changed the HG. Yeah...I'd keep them on. Torque to 75 ft/lbs (that's max) and check again after 500 miles or so. Should be fine...use ARP from the start next time though

 

[supramike7m]

jdub is the man. good to have knowledge like yours around here, steppin up in jet jocks place. :bowdown:

 

[87nasupra]

Just did a compression test on my JDM engine :wiggle: i've put 3,000 miles on since my swap......it has the stock HG, and bolts ( i think ) but i checked the torque and it was almost 75 all around.

 

[Figit090]

i didnt read it all...but...why not leave them in? did one break?

i used them over again...and i believe this is the 2nd time its been done. they're reusable even as per-TSRM. they arent the best, but if you aren't going big HP or metal HG...they're fine.