ARP2000 bolts for 3.2 engine

[FabianK]

Hello all,
I have some questions regarding the ARP2000 bolts:
1) I installed the bolts with a stretch gauge and torqued them to the recommended stretch of 0,01inch. Unfortunately I found out that the gauge has some accurancy though handling. I made a statistic and came to the result, that my real stretch of the bolts is somewhere between 0.009 - 0.012inch. Tolerance is 0.01-0.0105inch.
I'm questioning myself whether I can stay with it or not. Does somebody know how close 0.01inch is to the tensile strength? I hope there is still some safety, especially when you torque without a stretch gauge to the specified 40ft/lbs the tolerance will be much more then 0.01-0.0105inch, or am I wrong?

2) When I compare the bolts to the original bolts I'm questioning myself if there really such a big difference. Why do I think so. Torquespec of the original bolts are 15ft/lbs + 90degree. The thread has a pitch of 1mm = 0.04inch. So the original rod bolt will have a stretch value also around 0.01inch like the ARP2000 bolt. As both materials have a similar e modulus there can not be such a big difference in clamp load or let's say just a little difference if original rod bolt has a smaller elastic range. Or do I have a mistake in my calculation.

Appreciate your help!
Regards
Fabian

[David]

Tensile strength is probably about 150 ksi for ARP studs (should be on their website)

Estimating 6" length and 5/16" (just a guess), 3600 lbs preload stretches 0.01" with a stress of 47 ksi.

I'd release and restretch.

Good if you can measure stretch instead of torque since it's much more accurate but of course most people don't.