ARP and "cycled" read this!!!!!

Anonymous · Post by **Anonymous** » Sat Oct 27, 07 12:16 pm

Main studs..... Arp clearly state they should be "cycled" 5 times.. including the final torque, if this isn't done then the final torque figure is a waste of time.

So to instal correctly, main studs should be torqued 5 times, the first 4 times stretch the stud, so within it's design parameters it will not stretch further and stay there.
The final torque stretches the stud and this is what keeps the whole lot tight but again, within it's design parameters and correct torque (not over torqued) the stud will recover when loosened

If the stud is just torqued once then over a period of time and load it will stretch at least the amount the 4 times torqued + the final is supposed to remove, as it stretches the torque figure is reduced and so is the clamping force

Rod Bolts...... ARP recommend using a stretch gauge instead of a torque wrench and measuring at every rebuild, replace if .001" stretched

but ... taken from the arp catalogue
Friction is an extremely challenging problem because it is so
variable and difficult to control. The best way to avoid the pitfalls
of friction is by using the stretch method. This way preload
is controlled and independent of friction. Each time the bolt is
torqued and loosened, the friction factor gets smaller. Eventually
the friction levels out and becomes constant for all following
repetitions. Therefore, when installing a new bolt where the
stretch method can not be used, the bolt should be tightened and
loosened several times before final torque. The number of cycles
depends on the lubricant. For ARP recommended lubes, five
loosening and tightening cycles is sufficient.
A rod bolt stretch gauge is one of the most important tools a serious
engine builder can own. It’s valuable in properly setting up a rod for
resizing, obtaining the proper torque load when installed in the engine,
and monitoring the condition of the bolt while in use.

again 5 times cycled if a stretch gauge is not used

cylinder head studs..... the same

you can't use a stretch gauge on main studs or head studs so 5 times

anyone looking for this info in the arp catalogue online it's near on impossible to find, download it and read the whole lot, there's plenty of reference

Cannonball · Post by **Cannonball** » Sat Oct 27, 07 6:15 pm

thanks for that neil

AllKiller · Post by **AllKiller** » Wed Oct 31, 07 7:37 pm

Got that Neil

cheers

MrNorm · Post by **MrNorm** » Thu Nov 01, 07 11:38 am

Good advice.

Because of that, I've always thought a rod stretch gauge would be a good 'club buy'!

Kev · Post by **Kev** » Fri Feb 15, 08 6:03 pm

For ARP recommended lubes, five
loosening and tightening cycles is sufficient.

This is to full stated torque?

steveo · Post by **steveo** » Fri Feb 15, 08 6:33 pm

this is good info

.. thanks for sharing wil (

neil)

Anonymous · Post by **Anonymous** » Sat Feb 16, 08 8:21 am

Kev wrote:
For ARP recommended lubes, five
loosening and tightening cycles is sufficient.
This is to full stated torque?

yes full stated torque, but ARP torque with their lube.

Steveo.... no probs, this info has been in the arp catalogue for ever but if you view it online it's near impossible to find, downloaded seems to be different for some reason