Odd looking bolt - has a small diameter shank compared to the thread - they obviously REALLY wanted the shank to stretch before the thread does!

40Nm to set the thing square and compress the gasket - the 90deg would stretch it about 0.5mm? The shank of these things will stretch way, way before the thread does - That was my impression of the thing anyway.

Most of the broken bolts I have heard of are caused by reusing the bolts?

Everything says "torque to yield"... Very particular teminology?
Not "torque to hold the sucker down" or "do it up untill it breaks - then back it off 1/2 a turn" but "torque to yield"?

Unfortunatly, none of this changes the fact that I really gotta do the "low coolant warning" modification.... Bloody Gli pauper pack!

You'll likely find that its not the AU Gasket that makes it last longer, but the new head bolts.

When my Head was done, the gasket was blown but it was because one of the rear bolts had snapped.

When comparing the old bolts to the new bolts, there was about double the amount of thread on the new bolts, presumably allowing them to bite in and hold better. (At least thats what I was told... Dave?)

Its because the end torque figure on the bolt is somewhere near 120nm. At that level factors such as dirt, friction and oil in the thread can give you an incorrect torque figure.

If you torque the bolt to 40nm, its a lowish figure and base setting that does not get affected too much by the dirt/friction/oil issue. Then when you do a 90deg turn, assuming that all bolts are 40nm, you are applying the exact same end torque level to all the bolts. There are no external influences on the overall torque on the bolt.



The thread was longer, as well as the head of the bolt was bigger. The story goes is that the original EL bolts had enough thread for a standard thickness head. If you shave the head once, or twice or 3 times (depending how much was shaved off) the lack if thread would casuse the bolt shaft bottom out in the bolt hole. Thus causing not enough torque/pull on the head and another leaking gasket.

A mate of mine who used to work for Ford said that unless the timing chain appears to have streched, or the case hardening has worn off, not to bother with the timing chain, apparently they last nearly forever and theyre an absolute bastard to change



Theres a local mechanic here who works on all the falcon taxis and he did some experimenting and come up with a better torque for EF-AU head bolts, none of this 40MN+90 deg. Hes had AU taxis do head gaskets at 150,000, and since he derived his own torque setting hes never had to do a second head gasket. But he wont give away his secret though...

im just about about to hange my head over ow. About $95 for an AU head gasket and have been old to toque head down as follows. 40nm then 80nm then 110nm and make sure ead and bock are clean as also doulbe toque your boltsie go over then twice before going to the next step.
Hope this helps.

should be able to r&r the head in about 5 hours.

Shane.[/quote]
A mate of mine who used to work for Ford said that unless the timing chain appears to have streched, or the case hardening has worn off, not to bother with the timing chain, apparently they last nearly forever and theyre an absolute bastard to change

[/quote]


yeah in my eb the timming chain guide wore thin and dropped in the wall and jammed the chain, which snapped and the broke rocker arms and bent valves took me ages to line the new guides chain tenisher, and the the TDC was another story.