and if more torque is needed to get the desired stretch, why not just up the torque value, say 10, 15# , or whatever extra ?
wouldn't that basically "average out" the desired stretch ? [provided the correct lube in the correct amount is used]
In my experience if you do that and chase the stretch, you end up putting a lot more pounds on the fastener than the recommended torque.
But isn't the recommended torque selected to give you (approximately) the proper stretch? Stretch is all about the clamping force which keeps your rod cap on as the piston reverses at TDC...
I put my 451 together with Eagle rods and ARP bolts... there was a surprisingly large spread in the amount of torque required to reach .0063" stretch. I think it was something like 15 or even 20 ft-lb between the loosest and the tightest (it's been a number of years and I didn't write it down). That was after one cycle for trial assembly.
The torque required to reach proper stretch has a lot to do with the amount of lube used, the machined finish of the washer, nut, threads and rod cap on each fastener
