Arp Rod Bolt Torque

[JeffR 51]

I happened to be looking at the rod bolt specs on the ARP website for the XU engine & noticed that the torque figures have changed from those that were supplied with my bolts. (Part No. 117-6101).

 

arpinstructions.com/instructions/117-6101.pdf

 

It was recommended to torque to 35 ft. lbs. in the sheet that came with mine, but the website now recommends 45 ft. lbs.

 

The only differences I can see between the 2 sets of figures is a slightly different assembly lube used.

 

Mine goes on the dyno tomorrow & could be revved somewhere north of 8000 depending on whether it's still making power.

 

So should I ignore the difference & go as planned, or maybe have a lower upper rev limit?

 

 

 

[Vili 17]

I used 40 ft lbs because couldn't decide which instruction to follow. Of course it would be better to use stretch method if you have calibrated caliper of big enough micrometer.

You must have pretty extreme engine to rev it past 8k. ​ Solid lifters, forged pistons, billet conrods, double valve springs etc.. and a camshaft with duration past 300. Not to mention short throttle bodies and custom made 4-1 exhaust manifold.

[welshpug 1,626]

As above!

 

Secretly built a maxi engine??

[petert 554]

He does have all that!

 

With a little warning you good have borrowed my rod mics. I'd go 45Nm.

[JeffR 51]

Well I have in excess of 45 Nm-not by much 'tho.

When I discovered the different spec I remembered reading somewhere, probably on this forum of some rod bolt failures which made me think they may have revised their figures.

Car is lashed down on the trailer, so not in a position to do an all-nighter & tighten them up-especially with rain & hail predicted tonight too!

I'll have fingers & toes crossed that all goes well tomorrow.

[petert 554]

I hope all goes well. Looking forward to hearing of the results.