haha, I should just do a quick FEA of it next time I'm bored at work.

I'll be putting the head back on my car this weekend hopefully. I'm planning on torquing them to 65 ft lbs as well.

Found this today with some old papers in the garage. Installed mine before this thread started and probably followed the instructions. Guess I will just need to wait and see what happens.

Received an email from ARP after the floods destroyed all our build diarys,

Sorry to hear you lost some things in the flood! Here are the torque
numbers you need. They are the same for both the ARP Ultra Torque and
ARP Moly Lube.

Rod Bolts 118-6401 = 38 ft/lbs
Head Studs 218-4701 = 80 ft/lbs
Main Studs 218-5401 = 60 ft/lbs

Regards,

Alan Nichols
Sales & Technical

Automotive Racing Products
1863 Eastman Ave.
Ventura, CA 93003
Toll Free: 800-826-3045
Ph: 805-339-2200
Fax: 805-650-0742
Email: alann@arpfasteners.com
www.arp-bolts.com



So I think I follow Savs recommendations

Terry

I am pretty sure 80 is way too much for our aluminum heads. The original ARP engineer who set up the studs for the application said 48 I believe and the stock specs for the OE bolts which should provide a lot less clamp force per torque amount is 56-60.

Bob

So if the head bolt spec is off then what should the rod and main bolts be torque to? I am about to rebuild my engine.

Have a great day,
Jared

Would there be benefits to using oe sized washers with the head stud kit? Perhaps the higher torque numbers would not damage the head with more area under the washer for said tq to be exerted onto or would it be such a small increase in od that no difference would be realized?

I haven't seen the size difference but any time you can increase the area that will reduce the pressure/stress exerted on the face. Even small changes in area should produce a decently reduced stress. P=F/A

I can probably take some pictures tonight. I ditch the ARP washers and use OEM ones. They appear to be the same hardness but the OEM ones have a significantly bigger OD.

Bob

I torqued mine to 80ft/lbs a couple years ago, which seemed ridiculous when torquing them down at the time. I have, however, ran the engine without a belt on the water pump for 40 minutes in traffic (Had no water temperature gauge) before the upper radiator hose literally blew off the radiator. In normal cases with factory head studs, this would call for the head to be machined for sure. I just put the hose back on, threw a belt on, filled up, and I haven't lost coolant ever since.

Surprising that ARP would tell you this. The ARP2000 bolts that M-Tuned ships with their rods specify a stretch spec, not a torque spec. I've found that in order to get the ~.005-.006" stretch spec (IIRC), they wanted around 55-60ft.lbs of torque, not 38.

When I contacted m-tuned about torquing the rod bolts they specified 40-45ft lbs if not torquing to the stretch value.

Sorry to bring this back up. I just pulled the head, and plan on installing the new gasket this weekend. I originally torqued the nuts to 80 ft lbs per the instructions using the arp moly lube. After reading this thread it sounds like 65 lbs is a better option. Do I need to get more arp moly, is there a substitue, and do I need to measure the length of the threads for stretching with a micrometer? Keep in mind the threads had moly only when initially torqued, and now they will probably have a little oil on them. What is the recommendation for this scenario.

EDIT: It appears that ARP is now using the "ultratorque" lube which really minimizes the variance between torque stages. I think I screwed the pooch by tightening once, then immediately checking the torque again then buttoning everything up and never looking back. It appears that a person should probably use 8 separate torque cycles at the desired torque. How many cycles leading up to the desired torque before starting the 8 cycle retorque session? How long between cycles should a person wait before starting the next torque cycle???

Example: Pre torque 25%, 50%, 75%, 100% then 7 more cycles at 100% torque

+1

In for answer.

Just an FYI. This is why I said eight cycles to tighten. Then if you use assembly lube or motor oil you can be sure that you are getting the torque that you want. It also appears that a torque cycle is defined by tightening to spec, then loosening. I was unaware of this. I thought it meant tighten to spec, wait for any stretching then hit it with the torque wrench again to check. Using ARP assembly would clearly save a bit of time.

https://www.miataturbo.net/picture.p...pictureid=1840

That is very good info. Thanks for sharing.

I will say that the BP is not known for blowing head gaskets, and unless you are building a mega high horsepower motor, 8 torque cycles, tightening and loosening, and choice of lubircant is not overly important. Clamping a miata head to block is pretty forgiving of discrepencies in technique, with the exception of over torquing which has already been discussed.

There is no time component to fastener stretch. It stretches as soon as you preload it.

8 torque cycles is absolutely ridiculous. Use their recommended lubricant, torque it in 3 steps, and don't untorque it. All you are doing is uncompressing and recompressing the gasket, which is a bad idea.

Thanks Sav! :bigtu:

Back from the dead.

I just called FM and they say the 48lb ARP head stud number is not used by them anymore. They said 60-65lb for both the ARP head and main studs when using the ARP moly lube.

Why would we want to exceed the OE torque spec and thus clamping force if we know that the ARP studs are already stronger than OE bolts? Isn't the benefit in using the stronger studs? Or is there something to be gained by increasing the clamping force?

I'm reluctant to use ARP main studs at a higher torque if it forces a line bore since it adds $$$ to the build.

The increased yield of the material is of little use in stock preload applications. The modulus of elasticity which would determine the "clampyness factor" is pretty well absolutely constant for most steels. Unless you need a higher torque load on the bolt/stud the additional material strength isn't going to do you any good. In short... the studs should not apply any additional clamping force under stock pre-load. Higher then stock pre-load can cause problems as mentioned...

That being said, the tensioner bolt on my power steering pump broke today. I could just be bitter.