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Engine Specific Info and Questions => IDI Engine => Topic started by: overdrivegear on November 21, 2008, 09:04:07 am
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So what is the torquing procedure/values for using 11mm head studs? I understand that there is some grey area here and that some have used their own variations.
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i'm about to do a HG so i've been reading up, seems like most ppl use the value's from the manufacturer of the studs (arp, etc) instead of the bentley/oem values... but you're right, it kinda seems to be a gray area.
wait, are you using oem 11mm bolts or aftermarket studs?
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I used Raceware stubs (12mm) on my 1.9D engine and torqued them to the Raceware specs of 3 steps, 20-35-50 ft.lbs. then a retorque to 50 after running the engine to temperature.
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I have ARP's and used the normal pattern and torqued to 80 ft lbs. and then to 100 ft lbs. after a warm up.
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I have ARP's and used the normal pattern and torqued to 80 ft lbs. and then to 100 ft lbs. after a warm up.
you running the stock fiber gasket??
what kinda boost numbers are you pushing??
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I have ARP's and used the normal pattern and torqued to 80 ft lbs. and then to 100 ft lbs. after a warm up.
you running the stock fiber gasket??
what kinda boost numbers are you pushing??
Im wondering this too.
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I have some questions for you 'stud lovers'
1) Does ARP and Racewear use the same thread pitch on the nuts?
How does it compare with the block/bolt pitch?
2) Is it 25% or more finer? If so then can the heads be overtorqued? :shock:
3) When looking at a freshly removed head, I find that there are markings on the head from the gasket steel edges; so is that general abrading from heating and cooling of the head shuffling it around, or is it because the gasket has penetrated the head during the torquing process? :?
4) From my set of measured results when torquing stretch bolts recently. Initial plastic stage began at about 115 lb ft, then on the later retorque stage seemed less at a little under 100 lb ft. Why did the Germans settle on this peak? :?
5) After the 1000km run what has 'given' to allow bolt releasing at some 50 lb ft? head, bolt, or gasket?... Or has the bolt simply loosened? :?
[I know the releasing of the bolt was an old technique but I wanted the data, and I also wanted to avoid those gut wrenching snatches that some bolts undergo when overcoming their initial friction].
As I was retorquing to measured yield point only, be it 90 deg or as it happens around 45 deg; any further turning is a waste of stretch IMO :roll: :idea:
6000 miles on no leaks.
6) How much does a gasket give? Metric or imperial readings welcome. Does the quoted 1.4, 1.5 ,1.6 refer to the final settled thickness?
A 2 notch mech gasket I removed [blown] seemed to measure between 1.6 and 1.7mm at the rings some 30000 miles on... Seems like a spare replacement gasket I've bought is no thicker :?
Any thoughts anyone? :?:
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I have some questions for you 'stud lovers'
1) Does ARP and Racewear use the same thread pitch on the nuts?
How does it compare with the block/bolt pitch?
As I recall, the thread pitch on my ARP studs was the same on both ends.
3) When looking at a freshly removed head, I find that there are markings on the head from the gasket steel edges; so is that general abrading from heating and cooling of the head shuffling it around, or is it because the gasket has penetrated the head during the torquing process? :?
I'd say there would be an easy way to check this out. Clean up a head, clean up a block, throw a new gasket in there (Any size would do) and torque away.
Let it set for a bit, then take the head back off and check for your marks. For the record, when I redid the headgasket on the 1.5 in the Fox, and the 1.6TD I pulled a head from (Already studded :shock:), I didn't find ridges or marks beyond some discoloration from the gasket. I did, however, find a good amount of deposit on the 1.5 head in a ring that was just inside the fire rings in the headgasket.
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ARP studs are not the same thread pitch on both ends...one is definitely more course then the other..
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ARP studs are not the same thread pitch on both ends...one is definitely more course then the other..
Interesting, so if there is a minimum torque required, and a maximum to be avoided, then ARP's at least, require less torque for same clamping force; a 1/3 less or so, depending on the thread pitch...
I wonder if stretch bolts can actually stretch under load?
If pressure in a cylinder reaches 1000psi, then that's 6000lb thrust per cylinder :shock: or 1500 on each of 4 surrounding head bolts, or am I losing it :roll: ?
I guess it depends on the flexibility of a head :? so maybe it's 2/3 of that for the immediate bolts and a 1/3 of the force beyond.
What's the stretch force in a bolt? Are they1.5mm pitch?
Once stretched seem to carry on elongating @ or around 100lb ft.
I can't quite work it out in my head, but here's a guess; 305mm x 2PI /1.5... :oops: Heck that looks like nearly 1200lb to stretch. I guess I'll have to dig out my Victorian maths books :roll:
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I'm confused about all this head stud quandary. There should be no debate or variation - just follow the manufacturer's specification, e.g. 80 ft-lbs for ARP 12mm studs with ARP lube and a retorque after one heat/cool cycle.
Fastener torque is a function of material composition, diameter and thread pitch.
Chris
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Stretch bolts or studs can indeed stretch under load, causing sealing problems.
That's why I wasn't content with ARPs and instead went for custom studs.
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I'm confused about all this head stud quandary. There should be no debate or variation - just follow the manufacturer's specification, e.g. 80 ft-lbs for ARP 12mm studs with ARP lube and a retorque after one heat/cool cycle.
Fastener torque is a function of material composition, diameter and thread pitch.
Chris
Surely you mean fastner 'strength' is a function of your variables...
Torque is function of the job you wish to accomplish isn't it :?: ....
One of the aims of this thrashing out is to understand why head gaskets fail.
Also is warpage solely down to excessive heat and overloading, or also is actual distortion down to over zealous torquing.
I have a tendancy to under torque bolts, that is to say, do less than recomended, [where I think appropriate that is :oops: ]
Head gaskets deteriate,and fail after time too, but I'm wondering if extra care in attaching the head to the block increases the chance of reusing the head post gasket failure...
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I'm confused about all this head stud quandary. There should be no debate or variation - just follow the manufacturer's specification, e.g. 80 ft-lbs for ARP 12mm studs with ARP lube and a retorque after one heat/cool cycle.
Fastener torque is a function of material composition, diameter and thread pitch.
Chris
Surely you mean fastner 'strength' is a function of your variables...
Torque is function of the job you wish to accomplish isn't it :?: ....
One of the aims of this thrashing out is to understand why head gaskets fail.
Also is warpage solely down to excessive heat and overloading, or also is actual distortion down to over zealous torquing.
I have a tendancy to under torque bolts, that is to say, do less than recomended, [where I think appropriate that is :oops: ]
Head gaskets deteriate,and fail after time too, but I'm wondering if extra care in attaching the head to the block increases the chance of reusing the head post gasket failure...
they say to torque the head down in a sequence for a reason, as well as removing the bolts/studs in the same sequence. this is to reduce the likelyhood of 'warping' the head. the distortion of the head/block is directly related to the torque applied to them. this is why good engine rebuilders will use a torque plate to hone the cyl walls :wink: i would imagine that after heat failure, the head will require re-surfacing, or even be rendered non-repairable. the fiber gaskets must be prone to failure over time, but i would assume the 1.9 head gaskets to be a big improvement, and since made from 100% metal, should not fail under normal circumstances. but must be changed each time the head is removed, much like heat shields must be changed when pulling the injector.
now about the ARP studs vs Raceware - i believe that the raceware ones have much less of a thread pitch than ARP. they require about 50-60 ft/lbs whereas ARP require 80 ft/lbs with their lube. i would say that Raceware's 'unique' coating to be matched to ARP's moly lube. i had a very nice sheet with my racewares that i lost, but it described torquing in good detail. it talked about friction losses, etc. and about clicker torque wrenches vs beam, and another type i forget... thread pitch has a lot do with it as well. as you can imagine, it will be much easier to turn the nut that uses a very low thread pitch, and thus decreases the torque required to achieve the same clamping force. you can relate this to gearing.. 1st gear in the car requires lots of engine rpm's to achieve the same speed as the car in 5th gear, but the power output to the wheels is greatly reduced in 5th gear.
hope that helps!
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and a retorque after one heat/cool cycle.
Fastener torque is a function of material composition, diameter and thread pitch.
Chris
The ARP tech told me a retorque was not necessary on studs as they are not stretch fasteners.
A standard head bolt stretches thus the retorque needed but studs = no stretchy.
I'm not saying don't do it just repeating what i was told.
That being said when I get my G60 VC back from powder coating I'm going to add 1/8 or 1/4 turn to each stud while it's off.
Kinda scary though as I'm already @ 100 ft lbs.
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IMHO...if your using a fiber gasket you should retorque NO MATTER WHAT!! weather your using studs or bolts...
I think if your gonna run fiber gaskets then you should warm up the engine WITHOUT the cooling system cap on(no pressure) then let it cool and retorque to 80ftlbs....if your running MLS & studs then clamp the bugger and go...
my.02
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That's what I've done the last 2 times and been fine so far.
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What is the ARP torque spec for 11mm head studs? Is it the same for the 12mm at 80 ft.lb?
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I have ARP's and used the normal pattern and torqued to 80 ft lbs. and then to 100 ft lbs. after a warm up.
you running the stock fiber gasket??
what kinda boost numbers are you pushing??
I have the MLS gasket and am running stock boost - for now.
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Stretch bolts or studs can indeed stretch under load, causing sealing problems.
That's why I wasn't content with ARPs and instead went for custom studs.
ARPs are not "stretch" studs.
I'm confused about all this head stud quandary. There should be no debate or variation - just follow the manufacturer's specification, e.g. 80 ft-lbs for ARP 12mm studs with ARP lube and a retorque after one heat/cool cycle.
Fastener torque is a function of material composition, diameter and thread pitch.
Chris
Surely you mean fastner 'strength' is a function of your variables...
Torque is function of the job you wish to accomplish isn't it :?: ....
I meant what I said but could have elaborated a bit more. The engineered torque spec for a given piece of hardware is a function of the above properties - it's not a value or procedure than can be applied at random or on a whim to fasteners of varying design.
And yes, a re-torque is far more important with fiber gaskets after a heat/cool cycle since the gasket will compress as the block and head expand when heated, then retain the compressed state upon cooling. My steel gasket still allowed an additional 1/8 turn up to 80 ft-lbs after the first cool-down. Just standard procedure for the most part.
Chris
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"Fastener torque is a function of material composition, diameter and thread pitch.
Chris"
I guess you missed off the words 'spec' or 'max' and maybe 'applied' :wink:
Aren't these studs universal... in that I assume they might be used in other engines after all VW doesn't have a patent on 12mm studs; so that the same stud will likely have a slip of paper carrying different tightening spec, for a different engine or are all heads clamped the same?
So do you know how much a fibre gasket collapses under the specified torque? It clearly does because of the perimeter of the gasket shows a ridge , .I've tried measuring andn old gasket but I suspect the edge of the gasket exposed to the weather swells beyond it's original thickness.
Part of my research into this topic is because all the aftermarket gaskets I see on ebay seem to have different hole/notch arrangements depending on the manufacturer. I'm just not willing to pay for stealership prices, which would of couse [presumably] make life easier but means I pay the same for a gasket as I did for the car:roll:
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I need to double check, but the 11mm ARP studs I just installed in my 1.5 came with instructions that said to torque to 60 ft-lb. I only have ~60 miles on the rebuild, but it sounds like I could do an additional torque to 80 ft-lb after a couple hundred more miles and then call it good? Or should I do it sooner rather than later?
For what it's worth, I'm not losing any coolant or oil at all so far... but I'm seeing oil pressures well in excess of 100 psi (pegged to the back side of the stop in my mechanical 100 psi gauge) when cold, measured at the head. Once warmed up, it gets up to 100psi when floored still, but at idle it's around 30 psi.
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I need to double check, but the 11mm ARP studs I just installed in my 1.5 came with instructions that said to torque to 60 ft-lb. I only have ~60 miles on the rebuild, but it sounds like I could do an additional torque to 80 ft-lb after a couple hundred more miles and then call it good? Or should I do it sooner rather than later?
For what it's worth, I'm not losing any coolant or oil at all so far... but I'm seeing oil pressures well in excess of 100 psi (pegged to the back side of the stop in my mechanical 100 psi gauge) when cold, measured at the head. Once warmed up, it gets up to 100psi when floored still, but at idle it's around 30 psi.
if I was you I would do a re-torque SOON..but I don't know about what FTlbs to go to?? I know for sure my 12mm ARP's said 80FTlbs..11mm studs may only be rated for a 60ftlbs torque so maybe you can go 65-70 if you want a over torque???? yes? no?
your oil psi sounds normal to me...you reading at the head or oil filter flange??
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ARP 1-800-826-3045
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"Aren't these studs universal... in that I assume they might be used in other engines after all VW doesn't have a patent on 12mm studs; so that the same stud will likely have a slip of paper carrying different tightening spec, for a different engine or are all heads clamped the same?
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Fastener torque is the same across the board, regardless of the engine design/brand/etc. As I said, the torque spec is a function of the fastener design, not the engine design. The fastener will break long before "crushing" the head or pulling *undamaged* threads from the block. The slip of paper says "80 ft-lbs with ARP lube".
I need to double check, but the 11mm ARP studs I just installed in my 1.5 came with instructions that said to torque to 60 ft-lb. I only have ~60 miles on the rebuild, but it sounds like I could do an additional torque to 80 ft-lb
Then 60 ft-lbs would be the spec for 11mm studs. Don't overtorque to 80 ft-lbs.
Chris
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Fastener torque is the same across the board, regardless of the engine design/brand/etc. As I said, the torque spec is a function of the fastener design, not the engine design. The fastener will break long before "crushing" the head or pulling *undamaged* threads from the block. The slip of paper says "80 ft-lbs with ARP lube".
Then 60 ft-lbs would be the spec for 11mm studs. Don't overtorque to 80 ft-lbs.
Chris
This is interesting, so although the studs are obviously stronger than the stretch bolts they are not as strong as their threads, nor the block threads for that matter. So is the 80lb ft spec taking into account non standard boost , like some of the racer types that run nearly 30psi??
Anyone know the alloy, or simply breaking strength of a stud?
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The engineers have calculated that at 80 ft-lbs with ARP lube (120 ft-lbs with 30 wt), the studs will then be loaded to something like 142,000* psi for that thread pitch (1.75?).
The given torque value is designed to draw the stud to a specific percentage of the yield point for that fastener's material. So with a design load of 75%, the yield point is 190,000 psi.*
If extreme boost is causing head gasket failures, it will be because the head is deforming between the studs which is not uncommon as I understand. I can't imagine that ARP would recommend to exceed their engineered torque value for any reason - this would be the time to step up to the next larger stud diameter (I'm not saying this is even possible).
I do remember there being a general rule of thumb stating that a certain ratio of thread depth to fastener diameter would result in the threads being stronger than the fastener. With the 12mm ARP studs threading to a depth near 2x the diameter, the threads that are cut into the deck surface will be more than strong enough as long as they aren't damaged in any way. This depth to diameter ratio would obviously change with fastener material and minor diameter and even the thread form so this would require some research to be accurate.
Edit: I don't recall if the ARPs neck down between the threaded ends but I bet they do. If not, the likely failure point will be in the minor diameter of the coarser threads, just above where they enter the deck threads. Otherwise the studs would ultimately fail at some point along the smallest diameter, assuming no other defects exist.
* - edited again using VW_Commuter's values.
Chris
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Looking at my new set of ARP headstuds, part no. 251-4701, the installation instructions say the yield strength of the studs is 190,000psi. The instructions also state
Torque values are based on 75% of the fasteners yield strength. Use the manufacturers torque sequence but do not use the engine manufacturers torque specs. Torque the nuts to 80ft. lbs. for ARP MOLY ASSEMBLY LUBRICANT (or ARP THREAD SEALER) or torque the nuts to 120ft. lbs. with 30wt. motor oil.
If someone wants I can scan the instructions and post them as a jpg.
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I need to double check, but the 11mm ARP studs I just installed in my 1.5 came with instructions that said to torque to 60 ft-lb. I only have ~60 miles on the rebuild, but it sounds like I could do an additional torque to 80 ft-lb after a couple hundred more miles and then call it good? Or should I do it sooner rather than later?
Recommended torque on the undercut 11mm ARP studs, from the slip I just pulled out of the box (Part # 204-4701), is 70ft-lbs with the ARP lube, 85 ft-lbs with 30w motor oil. It is recommended that "Due to the expansion rate of aluminum, it is recommended that the torque should be 65 ft-lbs" with the ARP moly lube.
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So I'm looking at the instructions that came with my 11mm heads studs- ARP part number 204-4203.
The instructions clearly state to torque the nuts to 60 ft-lb when using the ARP moly lube. There is no value given for use with 30-wt motor oil (the instructions say motor oil is not recommended).
HOWEVER... at the top of the instruction sheet, next to the stated strength value of 190 ksi, it says "10mm"... so I think they put the wrong spec sheet in the box.
Does anyone have the actual spec sheet for 204-4203 studs? I'm going to email ARP of course, but if anyone has it here first, it would be appreciated if you could enlighten us with the proper values.
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No reply from ARP today, but I did find generic torque specs on their website. It specifies 60 ft-lb for 10mm studs, and 71 ft-lb for 11mm studs (and 86 ft-lb for 12 mm studs)- all with ARP moly lube.
Look here:
(http://www.arp-bolts.com/Catalog/Catalog.JPG/ARPCatalog_0024.jpg)
So they put the wrong spec sheet in the box... well, I'll torque them to 71 now and hopefully everything will be fine. It hasn't leaked yet, so if I go tighter I expect it'll stay leak free.
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Notice the Red print: "The torque values represented here are intended to be for general information, not for specific installations."
I heard that the TDI guys using ARP studs were actually using a Ford Cosworth application. They experienced failures of head gaskets and were blaming ARP hardware, however I suspect that they were not torquing them down enough. If it were me, I'd probably torque it at least 20% more, as a TDI at 25 psi is way more cylinder pressure than any Cosworth engine will ever see. :P
Brendan
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Okay, new info:
I traded a couple emails with Paul at ARP. He did confirm that the wrong specs were sent with my studs. He says the torque for 204-4203 11mm studs for VW applications is 80 ft-lb with moly lube, or 85 with 30 wt motor oil.
However, this does NOT apply to diesels. He said they don't have info for this application. And yes, the info in the above chart is only a general guideline.
As for me, I'm going to torque mine from 60 up to 80 and leave it at that.
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Fastener torque is the same across the board, regardless of the engine design/brand/etc. As I said, the torque spec is a function of the fastener design, not the engine design. The fastener will break long before "crushing" the head or pulling *undamaged* threads from the block. The slip of paper says "80 ft-lbs with ARP lube".
Chris
So in the light of new information straight from the horses mouth so to speak, do you wish to change any part of the above statement? Or are you feeling lucky pabst? :lol:
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Fastener torque is the same across the board, regardless of the engine design/brand/etc. As I said, the torque spec is a function of the fastener design, not the engine design. The fastener will break long before "crushing" the head or pulling *undamaged* threads from the block. The slip of paper says "80 ft-lbs with ARP lube".
Chris
So in the light of new information straight from the horses mouth so to speak, do you wish to change any part of the above statement? Or are you feeling lucky pabst? :lol:
Wow, talk about throwing gas on a fire 8)
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Fastener torque is the same across the board, regardless of the engine design/brand/etc. As I said, the torque spec is a function of the fastener design, not the engine design. The fastener will break long before "crushing" the head or pulling *undamaged* threads from the block. The slip of paper says "80 ft-lbs with ARP lube".
Chris
So in the light of new information straight from the horses mouth so to speak, do you wish to change any part of the above statement? Or are you feeling lucky pabst? :lol:
Wow, talk about throwing gas on a fire 8)
Ha, now that's funny cus I forgot I'm lurking 4000 miles from home and I was thinking how'd ya do that? 'course -4000miles, and over here we say "don't put petrol on a fire"... I was struggling with the image of methane.... :mrgreen:
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No I don't want to change anything that I said. Study fasteners and the properties of metals before "throwing gas on the fire".
I'm not here to argue with ARP or anyone else - their engineers (not their salespeople) design and spec their hardware to meet a balance between performance, reliability and liability.
Anyhow, my beef was with all the debate about how to torque ARP studs. My answer was to follow the directions and you kept pressing me for more information. Again I say don't deviate from what the ARP engineers spec out for their fasteners - there should be NO QUESTION as to how to attach a cylinder head to a block using ARP studs. If you keep blowing the gasket then it's time to step up a bit - look at their chart posted above, they offer studs in 220,000 psi in the same diameter which would be a viable improvement over the 190k studs that everyone is using.
Tell me how the new information is in contrast to what I said, anyhow? 75% of yield is the same regardless of the engine.
Chris
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I think there is a bit of misunderstanding of how torque values are specified. In a very simplified form, there are two considerations:
Max torque for the stud material. Every stud or bolt has a maximum torque that is determined by the material, size, etc. If you go beyond this torque value, you can enter the permanent deformation range and you have permanently damaged and weakened the fastener. If you go too far, you will actually break the fastener.
Application torque is determined by the engineer based on a desired clamping force. This value can possibly be far below the max torque for the fastener. In the vast majority of cases this is the value you will find specified by the OEM of the engine, etc. A fastener does not have to be torqued to the maximum possible value to achieve the desired clamping force between two surfaces.
For a head fastener application, if you exceed the basic torque required to achieve the desired clamping force, you risk getting into a range where you can distort the block/head interface beyond what the entire system has been designed for. How much distortion you get and what effect it has on the life depends on far too many variables for me to get into. In most cases if a fastener is bought on strictly a size specification, the fastener manufacturer will give you a max torque for the stud itself. It is only when the fastener is purchased with a specific application in mind that they may provide a application torque. If using studs which are not TTY (torque to yield), don't follow the OEM recommendation for torque value plus X degrees of rotation. This type of value is specifically for TTY fasteners and you will get very different clamping forces if you do this on a non-yielding, permanent stud.
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So I re-torqued the studs today. I started off with a re-torque at 60 ft-lb, and all of them took around 1/8 turn to get back to 60... so it certainly seems that, regardless of what torque you decide on, a re-torque should be done.
After that, I went to 70 on each, then 80 ft-lb on each one, and they all tightened up nicely. Bolt #6 seemed to take a bit more to get to 80 ft-lb., but not enough to make me worry.
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I just got a reply from Zac at ARP concerning the torque value to use and he said:
The torque value given is specified more towards the diameter of the stud, the material of the stud and what it is being used for (i.e. cylinder head studs) and not the specific vehicle application. We use that torque specification for all head stud kits where the stud is 12mm and has a tensile strength of 200,000 PSI.
I'm not sure what the pre-load or clamping force is but since I'm not planning on boosting above 15psi right now I'm just going to torque mine to 86ft. lbs. with a Victor Reinz gasket and see how it goes.
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Good info - thank you Greg!
Chris
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That's what I've done the last 2 times and been fine so far.
Can anyone confirm the 'best' procedure to use on my 1.9TD ABL engine head bolts please?
Just fitted a new head,
have torqued the bolts (new ones of course) to recommended torque on Autodata and used the right pattern etc
Should I run the van through a few heatcycles and retorque them? should I tweak them when the engine is hot? (surely thats a bad idea>!!)
Having (hopefully unrelated) issues with cam cover gasket leaking at the front although the head gasket seems to be ok....no mayonnaise in the oil, coolant level ok, however I have only had it running today and not driven yet as still testing things.
All advice appreciated