Graham - I've always torqued, measured with stretch gauge, torqued some more, measured some more, etc. until I got the stretch within the range specified. Is there some other way to do this? Measuring simultaneously with twisting would save time, to be sure.

I used a torque adapter like this:
NAPA AUTO PARTS

You attach it to your torque wrench at a 90 degree angle so it doesn't affect the amount of torque measured/applied. I'll admit that I needed a helper in order to hold the crank, rod, torque wrench, and stretch gauge all at the same time.

I actually found that the old school beam type wrench made the most sense for this, so I didn't have to continually change the setting on my click type torque wrench. You probably can't do this with one of the ratcheting torque wrenches, since it needs to stay perpendicular.

So you applied a factor like this: •{Desired Torque to Fastener * Length of Torque Wrench} / {Length of Torque Wrench * Adapter Center to Center Distance (2")}

And how does this square with the 90 degree/perpendicular you mention?

•This Calculation Assumes That the Attachment is Aligned with Torque Wrench Handle When Torqueing Fastener

But I see the light - you have to account for the extra length of your lever arm. Perhaps that is why the old beam style was simpler? No adjusting of click stops when you had done the math?

You just don't need a torque wrench when you are using a stretch gauge just use a simple bar with a socket.:)

Making both measurements is trying to confirm a precise measurement with an imprecise measurement which doesn't seem helpful.

The 'ruling' measurement must be stretch as this is a far more accurate and repeatable value than torque - especially when torque is determined by a wrench with a 'click' adjuster which is a really nasty device.

A dial indicating wrench is far better but the industry has done a great marketing job persuading us that wrenches that click are accurate which is just not true.

If you measure stretch and torque and there are discrepancies I would guarantee that the error will be the torque measurement not the stretch.

Young's Modulus is a very basic material property and it is very, very stable.

thanks for all the tips everyone. I bought another set of ARP rod bolts as I just didn't want the uncertainty of getting this critical clamp wrong this time around. I will practice installing and measuring stretch with my 'old' set of bolts so I'm ready when its 'go time' with the new ones. I'll also measure the new bolts so I'll have a starting length value for each if I ever need it again. Much appreciated everyone. Heading to Disneyworld with the fam this weekend so will hopefully get started after the following weekend.