Spent a happy 4 hours re-assembing my plan b 1275 a+ engine ( complete with awfull red paint!)
Set my trusty snap on torque rence to 50ftlbs as per by book and tightened till it clicked. Seemed awfully tight to me to i borrowed another torque rence from the garage and appears the they are tightened to about 70ftlbs
If it hasn't stripped now then I wouldn't expect it to 'let go'
as you run it in. If you have managed to fit a copper head gasket
the nuts would need re torquing after a couple of hundred miles
so you could use a more accurate wrench then?? If you are
really worried why not fit a new head stud/nut.
When you torque a bolt you are stressing the bolt ie stretching it. If you stretch it too much it will yield. The risk with over tightening is there is less stretch left for normal operating conditions ie expansion due to heat .
However using a torque wrench is very imprecise. Many factors can effect the actual preload or stretch of the bolt. The main one is friction on the threads and under the head. High spec engine fasteners such as ARP specify a special lube to try to get consistent torque readings.
Friction is another reason why when torquing you double click the wrench. Torque up, the wrench clicks, release then re click.
