stock head studs reusable?

**Marus92** · 03-02-2011, 07:57 PM

Originally Posted by gezed

yeah Marus, Ive read something similar to what youve described, angle torqued studs are usually torqued beyond the point of elastic stretch to what they call plastic stretch. I also contacted a nissan/infiniti dealer and the guys told me as long as the studs has no visible damage to them, then they should be reusable....but i have a feeling the dont really know what they are talking about

On a side note, arp head studs from what ive read dont need to be angle torqued, the spec was 86ftlbs instead
can anyone correct me if im wrong?

It wouldn't be torqued to plastic deformation for a few reasons. Main reason is that plastic deformation weakens the atomic structure and it's integrity; inter-atomic fissures cause the metal to decrease it's ultimate yield. The structure deforms in the plastic domain to diffuse energy from the strain of elasticity, becoming soft and microfissure prone.

Basically take for example people who torch springs; you get one saggy POS spring that makes the car lower because the atomic structure slowly cooled to a softer state, reducing the spring rate.

**nelsonmxmarc** · 03-02-2011, 08:28 PM

You can reuse arp studs, because they DO NOT stretch (or if they do it's not detrimental to the characteristics of the metallurgy). Marus summed it up.. Stock bolts stretch, it's the nature of that particular metal. And this is the reason the the head torque sequence in the fsm states to return to 0.. One torque sequence stresses the metal, whereas the following one seats it. Arp doesn't require this, as structurally they remain integral, and arent supposed to stretch.

Different story for conrod bolts..

**nelsonmxmarc** · 03-02-2011, 08:29 PM

80 ft/lbs is what arp recommends. The general consensus is to go +5/10 above. I went to 85 to be safe. OEM
is 90 if I'm not mistaken..

**M13** · 03-03-2011, 02:10 AM

89ft/lb as per OEM FSM.

I dunno, ARP studs are like 250 bux (not 100, I dunno where you are coming up w/ these prices LOL) and I would think it's a good insurance for building up an engine with a budget in the thousands...

I guess I'm just crazy.

**caliber676** · 03-03-2011, 01:55 PM

Your supposed to replace any torque angle/torque to yield bolt if your a decent engine builder.

**RSTuning** · 01-11-2012, 12:30 PM

You can reuse arp studs but you should measure them prior to initial installation, if being re used the original measurement should have not been affected. if it has then replace them with new units.