"C. E. White" > wrote in message This is done
using specialized machines
> that sense a change in the stress strain relationship as the bolt reaches
> the yield point. This is a very good way to torque bolts for variable
> loads, but difficult to duplicate in a repair environment.


I have seen bolt elongation gauges advertised and recommended for
performance
engine building. They are not so expensive.

I have never used one of them, and wonder if anyone here has any comments on
them.