QUOTE(Cevan @ Jul 13 2009, 12:57 PM)
I don't believe any torque spec is in the Haynes manual. I thought that the exhaust studs were torqued to 14 or 14.5 ft/lbs (because they're going into aluminum and the copper nuts that hold the HEs on were 12 ft/lbs.
Someone please render a decision.
That's right. M8 into aluminum is only 14 ft-lbs. Remember that though the nut is steel (copper-plated only!) the torque is distributed down the length of the stud, and the other end goes into aluminum.
I have the Bentley manual for VW T4, and it states 14 ft-lbs also, IIRC.
Interestingly, M9 into aluminum is about 17 ft-lbs, which is about the same as M8 into steel, so if you're running 9mm/8mm step studs, both ends can handle 17 ft-lbs, and you can go a but tighter.
Someone correct me if I'm wrong, but didn't the 1.8 came from the factory with the 9mm/8mm step studs. My theory is that this was part of the reason. Similarly, the rocker studs are 8mm/7mm step studs, with the big end going into the aluminum head- same reason? Who knows!