Conrod Bolts Torque Settings

[lockyer89]

I've just put some ARP bolts in at 35lbs (following the haynes bible) but I've read somewhere else 40...is 35 ok?

[steve in stockport]

You should be following the instructions that came with the bolts, haynes values don't apply to non-standard parts.

For my ARP bolts it was tighten to 32lb, slacken then retighten to 32lb, slacken and then retighten to 32lb for a third time

[blue]

No no no. !!! Never tighten then slacken ARP bolts. All you do is use the lube that comes with them then tighten to 25lb ARP bolts shrink in use if you over tighten them they will over stretch and potentially snap!!

The instructions clearly say tighten once ONLY

[Longboarder]

I think it might be wise to look at the ARP site and read the instructions for the bolts you have. Various methods are given for various bolts/applications. For con rod bolts I like the idea of use micrometer to measure length of bolt, note it down, lube, fit tighten ideally in one go whilst still measuring till stretched the correct amount. I also live in the real world, don't have three hands or a decent appropriate micrometer so have not used that method. I'm not aware that they shrink in use. I thought they were subjected to repeated cycles of stretch forces with each crank rotation and the idea is they are tightened enough that the elastic pre-load present as stretch is acceptably greater than the load they will experience so they never actually let the parts they are clamping move and never exceed their elastic limit and deform. Or something like that. I'm not an engineer but that's my understanding of it.

I used the tighten three times method for dummies that they give (used to give, looks like they have changed it!) for zetec conrod bolts. They haven't let go yet on four engines and I regularly rev the ST to 7500.

 

Nigel

[blue]

Sorry supposed to say stretch and over stretch !!!

 

Blond moment !!

[Bob Tucker]

These are for ARP rod bolts in a Pinto...

http://arpinstructio...ns/151-6001.pdf

 

heres the general site if you have something else

http://arp-bolts.com/p/instructions.php