Dave222 Posted January 10, 2008 Share Posted January 10, 2008 Help required, can anyone post the head bolt tightening sequence? Any help much appreciated. Cheers Dave. Quote Link to comment Share on other sites More sharing options...
jevansio Posted January 10, 2008 Share Posted January 10, 2008 I've been told that once you've torqued it down, it need bringing upto temp then fully cooling, before being retorqued (obviously removing all timing gear again). Can anyone confirm this? Quote Link to comment Share on other sites More sharing options...
Scooter Posted January 10, 2008 Share Posted January 10, 2008 12..8..4..2..6..9..13 14..10..6..1..3..7..11 this is with the cams on the left, and the back of the block on the right. ie 14..10 etc are intake side, 12..8 etc turbo/exhaust side. manual says (for TT).........tighten uniformly in several passes upto 34NM torque. then mark the front facing part of the bolts, do a pass turning each bolt a further 90 degrees and then a final pass of 90 degrees so that the marks are now all facing the bulkhead. no mention of retorquing (is that not for the mkiii?) Quote Link to comment Share on other sites More sharing options...
SimonB Posted January 10, 2008 Share Posted January 10, 2008 I've been told that once you've torqued it down, it need bringing upto temp then fully cooling, before being retorqued (obviously removing all timing gear again). Can anyone confirm this? I can confirm that's wrong! The standard head bolts are torque to yield. In other words you torque them to a certain level (34Nm or 25ft/lbs) in several stages and then a further 90 degrees. They deform when you do this, so you should not use them again. So you should not torque them more than once. The correct sequence is: front exhaust - 12 - 8 - 4 - 2 - 5 - 9 - 13 rear front intake - 14 - 10 - 6 - 1 - 3 - 7 - 11 rear Quote Link to comment Share on other sites More sharing options...
SimonB Posted January 10, 2008 Share Posted January 10, 2008 Bugger, beaten to it! Quote Link to comment Share on other sites More sharing options...
Scooter Posted January 10, 2008 Share Posted January 10, 2008 Bugger, beaten to it! no conflicting advice though so anyone looking in should be confident its the right info Quote Link to comment Share on other sites More sharing options...
Terminator Posted January 10, 2008 Share Posted January 10, 2008 The correct approach is as torqued down after several passes to 34nm 25lbft, then two 90 degree passes. Quote Link to comment Share on other sites More sharing options...
paul mac Posted January 10, 2008 Share Posted January 10, 2008 personally i would not attempt jobs like this without a manual (i got mine cheap off e-bay) and would recomend ARP head studs, superb and very straightforward to use, you just torque them down with no concern of angles and you can re-use them Quote Link to comment Share on other sites More sharing options...
jevansio Posted January 10, 2008 Share Posted January 10, 2008 I'm definately not attempting it , the reason I ask is ask you may know I've had a suspested head gasket problem. When the head was taken off they said that it had been lifting & moving (causing coolant to leak into the cylinders) and that it had been caused by over torqing it last time. Where does this retorque after heat/cool idea come from? They mainly work on Ford rally cars, I remember my mate talking about this 2 stage procedure when he had his cossie rebuilt? Is it an out dated procedure. I have ARP studs if that makes any difference (sorry for the hijack) Quote Link to comment Share on other sites More sharing options...
paul mac Posted January 10, 2008 Share Posted January 10, 2008 I'm definately not attempting it , the reason I ask is ask you may know I've had a suspested head gasket problem. When the head was taken off they said that it had been lifting & moving (causing coolant to leak into the cylinders) and that it had been caused by over torqing it last time. Where does this retorque after heat/cool idea come from? They mainly work on Ford rally cars, I remember my mate talking about this 2 stage procedure when he had his cossie rebuilt? Is it an out dated procedure. I have ARP studs if that makes any difference (sorry for the hijack) ARP head studs do not requiere a re-torque i recieved that from CW himself and mines been fine for 2 years Quote Link to comment Share on other sites More sharing options...
b_have Posted January 10, 2008 Share Posted January 10, 2008 Just re-fitting my ARP studs, anyone know what the studs should be torqued to? Quote Link to comment Share on other sites More sharing options...
Scooter Posted January 10, 2008 Share Posted January 10, 2008 strangely in the work manual after the torquing instruction it states......... "If any bolts break or deform, replace them" and " If any of the bolts do not meet the torque specification, replace the bolt" there is also a tolerances listing where "cylinder head bolt diameter" is listing as STD 10.8-11.00mm Limit 10.7mm Quote Link to comment Share on other sites More sharing options...
paul mac Posted January 10, 2008 Share Posted January 10, 2008 Just re-fitting my ARP studs' date=' anyone know what the studs should be torqued to?[/quote'] i followed the instructions with the studs, and went for around 60nm Quote Link to comment Share on other sites More sharing options...
jevansio Posted January 10, 2008 Share Posted January 10, 2008 ARP head studs do not requiere a re-torque i recieved that from CW himself and mines been fine for 2 years What are the draw backs of re-torquing (please note I'm not being an arse here, just want to learn the pro's & con's of each, and understand why mine is being retorqued), the thing is my head wasn't re-torqued last time & now it's off 6 month later as it's lifting. Is it a case of re-torqing is not necessary (although it won't do any damage) you are just wasting labour in getting to the nuts, or can you do damage by re-torquing when it's not necessary? Quote Link to comment Share on other sites More sharing options...
jevansio Posted January 10, 2008 Share Posted January 10, 2008 Just had a look on the ARP website, took this from their FAQ section: 3. Do the head studs only go in hand tight? The studs should be installed finger tight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. An undercut shorter stud will have a rate similar to a longer, standard shank stud. This provides a more even clamping force on the head. Because the head gasket will compress upon initial torquing, make sure studs (or bolts) are re-torqued after the engine has been run. Taken from here So what's correct? Quote Link to comment Share on other sites More sharing options...
b_have Posted January 10, 2008 Share Posted January 10, 2008 i followed the instructions with the studs, and went for around 60nm Lost my instructions years ago Its the actual stud torque I need not the nut. Quote Link to comment Share on other sites More sharing options...
SimonB Posted January 10, 2008 Share Posted January 10, 2008 The studs are supposed to be finger tight, no more. The nuts you should use moly assembly lube on and under, otherwise it affects the torque you need. Then you torque them in several passes to 65ft/lbs for aluminium heads IIRC. If you use ARP studs and bolts you could re-torque if you wanted to, it's just not necessary, and a major PITA to take the cams out etc for no good reason. Quote Link to comment Share on other sites More sharing options...
jevansio Posted January 11, 2008 Share Posted January 11, 2008 I also submitted a question last night to the tech guys at ARP via their website: Hi, just wondering if you can shed some light on this for me. I use ARP head studs on my MKIV Supra (built engine/head/single turbo). The head has lifted (probably due to incorrect torque procedure last time). The garage which are currently doing the work have advised that after they have fitted the head, the car is brought upto temp, then left to fully cool, before re-torquing. I know ARP studs should require no re-torque procedure, but are there any drawbacks in re-torquing the head after 1 heat cycle (other than wasted labour charges in access the nuts again). Any advice welcome, Best Jay Their response was: HELLO JAY YOUR MECHANIC IS CORRECT. WE RECOMMEND THAT YOU RE-TORQUE THE HEAD LIKE HE SAYS. THANKS RONF I think I'll let Motoscope carry out the procedure they're happy with. They did say that a lot of people miss out the re-torqing step due to the reason you say Simon, it's a massive PITA, but they say that it's a step that needs doing & it does have good reason (it means when my head goes on this time it's staying on ). I'm happy now Quote Link to comment Share on other sites More sharing options...
paul mac Posted January 11, 2008 Share Posted January 11, 2008 The studs are supposed to be finger tight, no more. The nuts you should use moly assembly lube on and under, otherwise it affects the torque you need. Then you torque them in several passes to 65ft/lbs for aluminium heads IIRC. If you use ARP studs and bolts you could re-torque if you wanted to, it's just not necessary, and a major PITA to take the cams out etc for no good reason. spot on Simon its ft/lbs not Nm as i quoted, you do not need to re-torque the head, i asked Chris Wilson this question in a thread (you may find it if you do a search- i couldn't) along time ago and he was kind enough to answer that no you dont, when i had my head off i did a lot of prep to the block (each water way carefully stuffed with cloth to avoid shit getting in) and the initial skim of the head was not smooth enough so i had it done at work on a lapping plate, the MLRS type gasket that the supe uses needs a very smooth finish if the head has excessive machining marks it will cause the gasket to fail during the thermal cycle, perhaps this is something you could check, there is nothing complex about bolting the head on as long as the prep is good Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 11, 2008 Share Posted January 11, 2008 MLS head gaskets do not need a retorque, this is one of the main reasons they were created, that and the fact you can no longer use asbestos in gasket manufacture. As a MLS gasket doesn't compress after the beads on the shim sections are crushed, it doesn't need a re torque. I have never had an issue with stock bolts and stock gaskets. There is an overwhelming desire in some quarters to assume stock everything needs binning as soon as you fit a dangly on the interior mirror When they say lifting and moving this would only occur if the head bolts or studs had lost all, or nearly all, preload. That would be bizarre, and I can only think of two scenarios to cause this. They weren't torqued up enough in the first place, or the things been got smoking hot, and the head, block, or both, have warped and stretched the fasteners. Quote Link to comment Share on other sites More sharing options...
paul mac Posted January 11, 2008 Share Posted January 11, 2008 as an add on to Chris's comments, the only reason i used ARP was the fact a few of the stock head bolts were out of tolerance and i could get the ARP cheaper (they are a peice of p**s to use though) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 11, 2008 Share Posted January 11, 2008 ARP fasteners are excellent, and if the budget runs to them they are a nice thing to have, although the stock bolts do the job just fine, too As Paul says, if you need to renew you might as well get the ARP stud and nut set, as they are cheaper if bought cannily. Quote Link to comment Share on other sites More sharing options...
b_have Posted January 11, 2008 Share Posted January 11, 2008 One thing with ARP that I struggle to get my head around is they say the studs should be installed 'finger tight' I have nipped mine up (only around 6lb/ft) for fear of movement. Quote Link to comment Share on other sites More sharing options...
paul mac Posted January 11, 2008 Share Posted January 11, 2008 One thing with ARP that I struggle to get my head around is they say the studs should be installed 'finger tight' I have nipped mine up (only around 6lb/ft) for fear of movement. i think they are finger tight to allow for expansion if you tighten them they could expand against the block and slacken off the head, i know it seems a bit odd when you install them and they have a cap head which is very tempting to get an allen key into but mine went in hand tight 2 years back and i have had no problems from when the cam covers went back on Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 11, 2008 Share Posted January 11, 2008 It is very odd, they are the only studs I have come across where they specifically say to NOT torque them down into the female thread. May be differential expansion, I don't know. Quote Link to comment Share on other sites More sharing options...
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