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Old 02-04-2006, 05:36 AM   #1
White 2.5rs
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Default Official Head Bolt/Stud Torque Specs for Various Motors

I'm running:

ej257
cometic SOHC gaskets
sohc heads
ARP sohc studs

what specs would you guys use on the studs, and have you had any problems running it like this.
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Old 02-04-2006, 11:57 AM   #2
CUNNINGHAM
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When using ARP head studs first you need to strech the studs you do this by installing all the studs finger tight, then use a old headgasket and tourqe the head down using the factory tourqe sequence and ARP spec's. The specs can be found on the box or on the web page. Do this five times this will put the studs at maximum strech. Should you skip this step the studs will loosen and a leak will occur. Someone I know made this mistake and within a day he had a leak. Once they are all streched loosen all the studs and install them finger tight again do not tighten them as this will cause them to pull more from the block than the head defeating the purpose of there design. Then tourqe them in sequence and to ARP's tourqe spec.

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Old 02-06-2006, 11:14 PM   #3
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thanks!
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Old 02-07-2006, 05:22 AM   #4
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Did this help you?
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Old 02-07-2006, 10:05 AM   #5
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yeah im stoppin by the dealership to get some crappy blown HGs because i threw mine away then im going to find out exactly which setup i have of ARPs and follow this diagram

alex
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Old 02-07-2006, 05:47 PM   #6
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You should have the 190,000 Tensile strength ones I am not sure what size. I would have to look at a set, the size may be on the top.
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Old 02-07-2006, 10:02 PM   #7
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Alex,
Do a search!
Cheers,
Tod
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Old 02-15-2006, 09:31 AM   #8
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Alright I got the lube, overnight from TWE, free of charge
anyways

I lubed the threads, inserted them by hand, some went in ALL the way, others only went in a little bit...

I took out the allan wrench and put them all to the bottom, backed them out, moved the lube back to the top of the threads because it got pushed backwards, and inserted them by hand....some bottomed out again by hand...I backed those out about 1.5 revolutions

I don't know what to think because it is weird that some were so easy and others were fairly hard to screw in

all of the threads were clean and unmarred <sp>

what do you think cunningham? anyone else?

thanks
alex
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Old 02-15-2006, 11:30 AM   #9
Matt Monson
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Sounds like there is some sort of muck in the block. I start by shooting brake cleaner into the holes and blowing it out with air until it is dry. Then, I always do a test feed with the head bolts. I grease them and thread them in by hand to get out any junk that may have been left in the threads. They usually come out with something on them and the grease less than clean. I then remove all the grease, re-grease them with fresh lube and do the head installation.

Now, I have never used the studs, but that's my approach with the factory bolts. But I don't see how that part of it would be different, other than you need to do the whole separate stud steps to stretch the studs...
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Old 02-15-2006, 11:40 AM   #10
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Mine did the same thing.
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Old 02-15-2006, 01:14 PM   #11
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Quote:
Originally Posted by White 2.5rs
Alright I got the lube, overnight from TWE, free of charge
anyways

I lubed the threads, inserted them by hand, some went in ALL the way, others only went in a little bit...

I took out the allan wrench and put them all to the bottom, backed them out, moved the lube back to the top of the threads because it got pushed backwards, and inserted them by hand....some bottomed out again by hand...I backed those out about 1.5 revolutions

I don't know what to think because it is weird that some were so easy and others were fairly hard to screw in

all of the threads were clean and unmarred <sp>

what do you think cunningham? anyone else?

thanks
alex
Ron at Axis told me to bottom them out. He also mentioned to do it dry. I guess his method is a bit different. Maybe give him a call and talk it over with him.

Then again some people re-use factory bolts, some use lube etc.

Louis
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Old 02-15-2006, 05:14 PM   #12
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Ok...I just talked to TWE and they said back them all the way down too...this would make the most sense

Alex
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Old 02-16-2006, 07:22 PM   #13
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All of this is normal. Just get them all seated down to the bottom. The most important thing is that you only put them in till the stop some you will have to install with a allen wrench and them back them off a bit. Once this is done you are ready to set the studs. The lube is very important, make sure you use it.
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Old 02-16-2006, 08:40 PM   #14
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hmm, well axis and twe have both told me to seat them to the bottom.

I just installed one side, i torqued them down 4 times, not 5 because i think 4 times is enough and then went around, did them in order to roughly 25 then to 65, then went around and held the torque wrench at 65 on them till they quit inching their way tighter

thanks for the chart and the hint about stretching them
alex
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Old 02-18-2006, 08:24 PM   #15
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Yes, they need to be installed all the way down but not tightened. The main reaseon is when you insall and tighten a bolt they pull from the threads up, causing a uneven clamping force. The reason we use studs is that it make for a clamping action, a even clamping. Take some time and research ARP head studs in there tech section. Acording to ARP the studs need to be streached a minimum of five to seven times. Full tourqe must be achived, if you don't further streach will occur when you don't want it too. Did you notice that when you peform the stud strech a few times it's hard to get the nuts back off. This is due to the strech.
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Old 02-18-2006, 10:04 PM   #16
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I'm not tryin to sound like a jackass but I noticed it was easier to get them off...which scared me...
I'm going to apply 65 lbs of torque to the studs daily for a few days, to make sure theyre not backing off or becoming loose
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Old 02-19-2006, 09:04 AM   #17
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Appropriate preloads are specified for each ARP bolt. These preloads can be attained in a bolt or stud by applying proper torque using a torque wrench or by measuring the amount of stretch in the bolt using a stretch gauge (it is known that a bolt stretches in proportion to the tension in it). The torque method is sometimes inaccurate because of the uncertainty in the coefficient of friction at the interface between the bolt and the rod. This inaccuracy can be minimized by using the lubricant supplied by ARP.

Other factors, equally as important as design, include material selection, verification testing, processing, and quality control. These aspects of bolt manufacturing are discussed elsewhere in this document.

The foregoing discussion concentrated on the design of bolts. The same considerations apply in the design of studs.

I would not just torque them to 65ft lbs. You need to apply the full load to get all the stud streach out of them and apply the proper pre load to the bolts as this will prevent bolt failer. Remember the bolts are only good as the installation. Do you have the instructions and the box that came with the bolts?

Read the Head bolt Vs. the Head stud section


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Old 06-15-2006, 10:08 PM   #18
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Is it bad to reuse stock head bolts?

If it is why don't they tell you in the service book.


Thanks
-Scott
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Old 06-16-2006, 11:53 PM   #19
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Stock head bolts are a different creature than the ARP fasteners. ARP's have a MUCH higher range of plastic deformation than OEM fasteners. They also hold a much a higher load than the OEM fasteners and hold it much more consistently. The OEM fasteners will specify a max. length they can be used. Anything longer and they need to be tossed. Usually the OEM fasteners will take 2-3 cycles before stretching too much. Unless you have an engineering degree and a notebook full of lab tests for your fasteners... read the bloody directions and follow them.
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Old 06-17-2006, 05:31 PM   #20
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I follow the instructions in the service manual very closely. I read them over many times and before I start I go to the Subaru service book corrections to make sure there isn't a mistake in the book. My first time putting the motor back together I broke a cam shaft bolt and the torque spec turned out to be wrong.

below a little more info on my car

I've had my wrx about 3 years now and its never run right. I've always had overheating issues and I have a bad feeling air is being forced into my coolant. I've replaced everything from thermostat to water pump to timing belt tensioner tried 3 rad caps. I've had the heads off the motor twice now. My car is back together and I've driven it a little and its acting up. Same thing all over again overheating filling the overflow tank dumping coolant on the ground and I can watch the overflow hose blowing bubbles into the tank.

Heads sent to head shop and checked, oem head gaskets used. I have pretty basic mods, big TMIC, TBE catless, TGV delete, STi injectors fuel pump, UTEC w/ TUNA I stay conservative on boost and haven't gone above 14psi since I put the motor back in a few days ago.

Here's the procedure I use for getting air out of the system.

I connect a mitivac to the top of the radiator to suck out air while I pour coolant it helps speed things up a little. When I can't add anymore coolant I turn the heater on high and start the car and take the rad cap off. I watch the bubbles come up and slowly add coolant until its full then put the cap on and go drive. I've done this twice to the motor I just put in my car and its still acting up.

In total I've had the motor out more than 5 times. I tried another motor but it gave me cylinder misfires codes like crazy but never overheated.

I plan on doing a leak down test and I would like to test coolant for trace of exhaust gas.

I believe I've been thru hell with this car. Countless missed & ruined track days. I still love my Subaru and plan to stick with it until it runs right.

Thanks

-Scott Amato
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Old 06-17-2006, 06:42 PM   #21
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what is the biggest reason people use ARP head studs over the factory ones? I would assume that my machine shop knows this 5 time procedure and will do it when installing my heads on my block...?

I didn't ask for ARP studs...should I? I'm running a cobb block on my DOHC heads...
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