[gtobird]

I've got stock resized rods with a set of ARP connecting rod bolts / nuts. Their directions indicate using their own Ultra-Torque fastener assembly lubricant. Any comments on using this vs the old school thought of loctite that was used on rebuilds with stock bolts / nuts?

The current train of thought as I get it is to focus on applying the proper bolt stretch and torque by allowing the nut to spin more freely with lubricant rather than using loctite which causes the nut to lock into place, but possibly with the incorrect torque and bolt stretch. I don't see that happening unless you waited too long and the loctite dried, but that's only my novice opinion. I can see that lubricant might help the bolts to be used for a couple of more rebuilds.

What do you engine builder gurus say?

[grivera]

Definitely use the ARP lube - never heard of using loctite on a rod bolt…

[mgarblik]

To get the correct clamping load, which is all that matters, you need to use the ARP lube. Their torque specs. are based on their lube. If for some reason you really wanted to use a locktite product on the rod nuts, you would have to use the stretch method.

[steve25]

Once a rod bolt gets over stretched in a running motor the use of Lock-tite buys you ( given upon the rpm) about 2 more milliseconds before parts start flying out of the motor.

I know all too well from experience that the hammering that takes place by a rod bolt going south even at as in my case a mire 2500 rpm is scary!

You’ed think that while driving someone was
was banging on your cars frame with 8lb sledgehammer.

Even minimal hammering that sounds like only detonation will easily just crack the Lock-tite out of the bolt threads.

The main reason stock rod bolts fail is that they where over stretched when they where used again by the rebuilder, or they where torqued up too many times.

I consider 4 times the limit and if on your street motor you want to play with fire go 5 times .

Remember that if you take an original factor motor apart and put it back together that your rod bolts have then been stretched 3 times already.

Keep in mind that the G force loads a rod bolt needs to deal with are exponential.
They are for example twice as high at 4000 rpm as they are at 3000 rpm.

A rod bolt that’s starting to go south could live forever at 4000 rpm and then send the motor to its destruction at 5000 rpm.

Add to this for example that just due to the stroke difference between a 400 and a 455 the G force loading is 12.5% higher for any given rpm a 455 is at as compared to the 400s 3.750” stroke loading.