hls > wrote:
>"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.

We use them on airplanes. They are much more accurate than torque gauges
because they don't rely on thread friction.

They would seem overkill for auto applications, but more importantly they
would seem useless because the numbers in the engine manuals are all torque
specs rather than elongation specs. So you'd have to develop your own
nominal values for reference, which is probably fine for a one-off engine
that is being constantly rebuilt but otherwise impractical.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."