ARP Head Stud Torque specs??

[Dweezle]

HI Guys,

Helping the lil bro put his built 1.6 together.

About to install the ARP head studs.
The spec sheet that came with them says 80ft lb.

Sounds crazy high as stock is like 54ft lb.
I then came across this thread on MT.Net.
http://www.miataturbo.net/engine-performance-56/arp-head-stud-torque-miata-54746/

Alot of people with different opinions.
A fair few saying 55 ft lb is more like it.

So i asked Emilo at 949 and he replied with this.

Well if you read it on the internet by a bunch of strangers, it must be true ;)

Use ARP's specs.

I still feel that a final torque of 80ft lb is too high, but am prepared to be wrong before actually doing it!!

Can anyone help a fella out with the truth?

Would really appreciate it!!!

[MrRevhead]

PM wozzah1975, he will surely know from his experiences.

[hks_kansei]

I'd still go by ARPs suggestion.


If you buy a pie and want to know what's in it, do you phone Caltex and ask? or do you phone Four & Twenty?

(although, I'm guessing ARP don't make their products from offal and filler like a pie company.......)

[Dweezle]

HAHA, good point.
I have pmd the god like Wozzah!!


I am more than happy to use ARPs specs but i have read about peoples heads cracking at 71ft lb on their way to 80ft lb from following ARPS specs.
This head has work done to it and losing it to stupidity would leave me locked in a dark dungeon after the bro threw away the key !!

[gslender]

I followed the ARP recommendations and all is fine here.

G

[hks_kansei]

I am more than happy to use ARPs specs but i have read about peoples heads cracking at 71ft lb on their way to 80ft lb from following ARPS specs.

Curious, the ones who had heads crack, were they 100% certain that there wasn't any oil/water in the bottom of the threaded sections of the head?

I know that people often crack heads in that way after they've blown a head gasket (water everywhere, they forget to clean out the holes, tighten studs, studs attempt to compress water at the bottom, water just finds another way out)

[Dweezle]

Good point, though cant imagine how you could crack the head that way.
The block maybe but the head just has the studs through it.
80ft lb is almost double the stock amount on a engine that has no head gasket issues with standard head bolts.

Hmmm apparently Flyin Miata cross the 80 out and say 47 ft lb.

Ughh

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[hks_kansei]

Good point, though cant imagine how you could crack the head that way.
The block maybe but the head just has the studs through it.

You're right.

My mistake, block, not head.

[gslender]

Yikes! You've now got me thinking twice about that advice in the box... 80 ft/lbs!

http://revlimiter.net/blog/2011/06/miat ... ead-studs/



G

[Dweezle]

Yeah, Scary hey.

I have had the good word that 60lb ft is all that is required.
Thanks Woz and Tbro

Bad new is we just discovered the OEM head gasket bought from overseas is cracked around a coolant port!!!!!
MOTHER F**KER!!!!

[gslender]

Mmmm... So when I was discussing head bolts, nobody warned against the 80ft-lbs instructions then !?

viewtopic.php?t=56640

I even thought a few others had done the same thing and did them up "bat sh*t insane" tight!?

I wonder if I should loosen and re-torque to a slightly less value???

Engine has been started a few times, but really only 5 mins and barely up to running temp. I've yet to run it in correctly, and only changed the first oil.

[sailaholic]

I went with the arp recommendation. No issues so far. Did run a tap into the block and clean out the threads.

I phoned waz at the time to double check as well as it was his head I was putting on. He said arp specs should be fine. Don't remember if it was 60 or 80, but I remember it was fing tight.

I don't see the point of putting in high strength studs and not torquing them up higher.

[Dweezle]

Damn..
I don't not much but I would think loosening would be a bad idea.
The head gasket has now been compressed.
If you uncompress it you may have issues.

I have read off a lot of people running with the 80ft lbs.
So your prob fine.
Emilio at 949 said to use that.

I will go with woz and tbros suggestion as I trust those guys.

If you have no issues I would think you'd be right.
Hopefully someone more knowledgeable than me will speak up though!!

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[project.r.racing]

Dont forget Mazda bolts and ARP bolts/nuts are 2 different setups. They have different op specs for that reason.

Never loosen ARP bolts, they stretch when tightened up.

[Dweezle]

I don't see the point of putting in high strength studs and not torquing them up higher.

Doesn't the finer thread on the ARP studs increase the clamping load?
So even if you matched OEM with 56ft lbs you would actually have increased the clamping load substantially.
Going to 80ft lbs would have to be double oem spec.

Again I have no knowledge here.
Just trying to get a better understanding of why?

Some say 80 is good, others 48.

No one seems to say why though.

Wozzah suggested 60-65ft lbs.
We all know Woz knows all!!
I will go with that!!


Also I believe you can reuse ARP studs on mx5 engines.
I was told by 949 that the torque amounts will not cause any stretch to worry about and the main reason people use the ARP studs is the ease of pulling the head on race cars.
ARP also suggest you can use loctite to permanently mount the studs for ease of removing the head.
Again, please tell me if this is wrong!!

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