Torque sequence for ARP 2000 rod bolts?

M

mmacquee

Well-known member
What is the torque sequence for ARP 2000 rod bolts - the ones in question have a 5/16 thread and the application is on Carillo connecting rods. ARP lube, tighten/loosen/tighten, and then final tighten to 28 ft lbs per one chart I have seen. Or?
 
From: http://www.cnc-motorsports.com/blog/con ... que-specs/

Torque the Rods
Rod bolt threads and underside of the nut should be lubricated with ARP Moly Assembly lube. Do not use oil or loctite. Cap should be seated on rod by aligning cap by hand and tapping in place. Alternatively tighten nuts to avoid cocking of the cap. ARP recommends that the rod bolts be tightened and lessened four additional times prior to assembly.
 
Mike, as an ex-HP Sprite racer, I think the sequence of snug/loosen/snug-torque then torque is ARP way of making that the lube is spread- just enough on the working threads but no gobs under the head- and any questions of binding or crooked fit will be resolved. Of course going from one bolt to the other of a rod cap is good practice as you build up. However, don't use tiny steps either, as each higher torque needs to overcome the static(stuck) friction of the previous level. Thus, go 20,25, 30, 35 etc rather than 20, 21, 22, 23...
However, the final torque value you give "seems low" and may only be good with new, perfect bolts, exactly the right lube, etc. - When we torqued the ARP 5/16 rod bolts on my 948 engine we were more like 35 ft-lbs as final value. We also had tested this by the "stretch of the bolt" method with a con rod assembly clamped in a vise, where we could fit a digital caliper or micrometer over the bolt. (It is too hard to measure the actual bolt stretch down in the actual engine block area.) We then used that value to torque all rod bolts - as long as we used the same lube, same process, etc...= Test one then prepare and do them all the same. Joel
 
Mike your Carrillo have a ARP2000 bolts, normally they come with either Carr, or WMC bolts, Carr bolts drive the price up on the rod about 400.00 for the set of 4, but they never need replacing, unless you damage one.
 
Thanks, Hap, I do have the CARR bolts, but since I bought the rods used I had no idea how many cycles the bolts had been through (the bolts have the SPS marking on the head, which is the mark of Carrillo's custom supplier). I picked up a set of the ARP 2000s but will hold those in reserve or send them back -
Now to get my torque wrench back to Snap-on for calibration, it's overdue.
 
I know, I have a stretch gauge, but I want an accurate reading of how much torque I am applying to get the bolt to the required stretch -
 
mmacquee":2oeuppx4 said:
I know, I have a stretch gauge, but I want an accurate reading of how much torque I am applying to get the bolt to the required stretch -
Click to expand...


Mike, sorry delay in a answer. Carr Rob bolts are like $70+ for each bolt, them and ARP Custom 625+ are the very best rod bolts made. Carr rod bolts have more life cycles than any of us combined could ever use, by going to a ARP 2000 rod bolt you would be going way backwards in strength, and grade.

If you already did this, can I have the old CARR rod bolts, I will pay shipping on them :)
 
Mike,

Why does it matter what the torque wrench says after you do the rod bolt stretch exercise? As long as you use the same unmolested torque wrench it doesn't matter what the torque wrench actually says. Just set it to the same number.

Save yourself some work as the rods and maybe the mains and flywheel are the only fasteners on a sprite worth getting really anal about. Others are less critical.
 
Just out of curiousity I wanted to know the torque figures. With the stretch gauge installed I was at about 32 ft/lb with my dial indicator torque wrench as the Carr bolts were reaching the desired stretch.
 
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