ARP fasteners

K

Kiwirob

New Member
Rebuilding a V8, seems to be a bit of info one way or another as to the torque values to use. Rodbolts are easy as you just measure the bolt stretch, ideas re head and particularly the mains is inconsistent. Suggestions run standard for the head fasteners and about eighty ftlbs for the mains. Speaking to ARP they suggest 110 using their lube or 135, yes 135 if using 30 weight oil on the main studs. I asked them if they actually got feedback from like any Buick specialists, the answer appears no. Hey it's not a Chev, can't expect them to actually know....or care. Anyone have some real life experience please?
 
Hi, I've recently done an engine rebuild and I used these settings -

Mains 1 to 4 - 50 to 55 lb ft
Main rear - 65 to 70 lb ft
Big ends - 30 to 35 lb ft
Head bolts 10 inner - 65 to 70 lb ft
Head bolts 4 outer - 30 to 35

The four outer one only really need to be nipped otherwise they can cause problems. One reason
is they distort the head, the other is that with composite gaskets it tilts the head. either way it
causes sealing problems. You can actually leave them out altogether as later engines don't have
them.

As far as ARPs numbers are concerned, were you using their stud or bolt kits or did they think you
were? Were they quoting you newton meters?

Colin
 
They were talking ftlbs, their suggestion is the amount required to get the max clamping force with the fastener depending on the lube used, which were all their part numbers for Rover/Buick215. The big ends come in at about 45ftlbs if using a stretch gauge, provided you use 'Ultra Lube'.
 
80ft/lbs is the recommended torque for arp main studs, but be aware that because of the higher torque from standard bolts you risk distorting the main caps and ruining the shell bearings. What needs to be done is have the main tunnel line bored with the arp studs fitted, torqued up and then machined by your engine specialist. I'm pretty sure the arp instructions specify this for their main stud kit but I've mislaid the paperwork, anyhow I've had this done on my standard 3.5 block, and same applies if using arp big end bolts.
Scott

just added below link for main studs, read footnote


http://arpinstructions.com/instructions/124-5401.pdf

And below link for big end bolts,

http://arpinstructions.com/instructions/124-6001.pdf
 
My research came up with 80lbs as well, but the ARP instructions are indeed 110lbs using ultralube, when I questioned them, they acknowledged it was a generic specification relating to stud size, hence my question if they had feed back from other builders. My machinist checked everything but used standard specs on the mains. The block was bored and then honed with a torque plate, and everything has been balanced. Quess I will have to check the mains again at the correct torque and see what needs to be done. Want it done right, do it yourself.
 
I just looked again at the arp instructions and you're right rob, it does say 110ft lbs, when I bought my set it specified 80ft lbs, and my engine machinist set them accordingly and engraved the 80ft lbs setting on the bottom of the block for future reference, and for whoever comes across the motor in the future no doubt. So mine will be getting torqued to 80ft lbs. I notice the new arp language is "ultra torque" so if it is now 110 for the latest stud kits then 110 it is, but still best to get the main tunnel line bored if using arp studs, I know it is extra expense but gives piece of mind when assembling.
Scott

Edit, just checked arp web site again and "ultra torque" refers to their latest fastener assembly lube product which looks like it achieves higher torque values compared to their previous moly product supplied in their kits.
 
Hi, I think it's more about the lubricant than the fastening. It suggests that it better at
avoiding the threads getting "torn up" and dragging, because that is where the most load
is during the tightening process.

As far as re-torqueing is concerned you will only get a true reading during the actual
tightening. If you were to torque a bolt to say 70 lbft, then adjust the torque wrench to
80lbft and tried again, the wrench would "break" without moving. The bolt hasn't got
suddenly tighter it's just that the friction hasn't been overcome. I was always taught not
to go back to a bolt to check again, do it once do it right.

Colin
 
ARP supplies a figure that allows max clamping force to be reached without the use of equipment to measure the stretch of the fastener. Ultra Lube was developed to provide consistant results and minimise torque scatter and the need to cycle the fastener to achieve a stable torque value. Their figure is based on say a half inch fastener, the pitch, lube used and there is even a formula to calculate it. The problem remains that a Rover block would not withstand the torque installation values that would allow the fastener to achieve max clamping force, bearing in mind the expansion of the aluminium as well. ARP have no current suggestion as to the installation they supply their product for, except the generic one, as mentioned before, 80lbs appears to be the accepted figure. There is a good video on YT I will post a link for when I find it, by a guy that worked for GM discussing the whole fastener issue. Be warned, if you think you know a bit now, you will feel you know a lot less at the end of it!
 
colnerov said:
I was always taught not
to go back to a bolt to check again, do it once do it right.
Click to expand...
In aviation, we are required to do torque checks at specified intervals after work is done to ensure torques have stabilised.
 
Hi, yes I agree, when changing wheels on commercial vehicles there is a requirement to
do a torque check after 24 hrs in case they have come loose in service, so after a work
period is understandable. What I meant was that after bolting a head down sequence
there is no point going round again straight away, it doesn't achieve anything because
you get a false impression.

Colin
 
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