jevansio 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. Chris, any idea why ARP recommend the head be re-torqued???? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 11, 2008 Share Posted January 11, 2008 Probably because it's impractical and expensive to issue instructions where they cite "if you have a MLS gasket" Or "if you have a composite gasket" blah blah. They just have generic instructions that covers their arse. If you retorque it should do no harm, whatever gasket you have, so they go for the simplest option. Quote Link to comment Share on other sites More sharing options...
jevansio Posted January 11, 2008 Share Posted January 11, 2008 Cool Quote Link to comment Share on other sites More sharing options...
dandan Posted January 11, 2008 Share Posted January 11, 2008 No point with the metal HG. In theory attempting to retorque them will actually do nothing at all anyway unless they are slackened slightly first. The friction when torquing a nut up (ie when the nut is spinning) is about 20% lower than the static friction (when the nut is just sat there and you attempt to tighten or loosen it). If you torque one to (let's say) 40lbf.ft and then use the same wrench set at 40lbf.ft again once it is already torqued nothing will happen...the wrench will click out...the nut will not move. ....that's why undoing a nut will always take more torque than when doing one up (it's typically about 20% ignoring any vibration/heat/corrosion etc). Quote Link to comment Share on other sites More sharing options...
Syed Shah Posted January 12, 2008 Share Posted January 12, 2008 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. Or, when your making a LOT of power (as these engines can), and you lift the head. Stock bolts are fine, up to a point, but they were not designed to hold the head to the block with the cylinder pressures generated by 100+ HP per cylinder. Quote Link to comment Share on other sites More sharing options...
Dave222 Posted January 12, 2008 Author Share Posted January 12, 2008 Sorry to be a stupid but what does MLS stand for? Quote Link to comment Share on other sites More sharing options...
jevansio Posted January 12, 2008 Share Posted January 12, 2008 Multi Layer Steel Quote Link to comment Share on other sites More sharing options...
paul mac Posted January 12, 2008 Share Posted January 12, 2008 Sorry to be a stupid but what does MLS stand for? lol just realised i put MLRS which stands for multi launch rocket system, sorry as well as being a petrol head i'm also a track head Quote Link to comment Share on other sites More sharing options...
Matt Harwood Posted January 12, 2008 Share Posted January 12, 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 nipped mine up using the short end of an allen key as the leverage, so no major torque. No problems here. Quote Link to comment Share on other sites More sharing options...
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