That brings me onto my next question.. What is the thread pitch of the M10 head bolts? I need to order a tap and coil inserts to suit.
I think the cause of my head gasket going was the problem of one of the head bolts stripped out of the head. I found this out when trying the old retorque head bolts trick.
I'm also ordering some screw and stud extractors for the intake bolts as a last resort if the torx bit trick doesn't work.

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Ben

'85 500 SEL
'85 928S2
'88 560 SEC
'90 750i