ARP main stud instructions

[Will L.]

@ak diesel driver asked about head bolt/ stud also, so added that for a couple more bucks. Glad I did because look at how much lower the arp clamps than the bolt on the head stud!
But the 10mm studs torqued at 50 as suggested by a few I think is mega overkill. The ARP guys I talked to before kinda freaked when I told them factory numbers and what the stud suggested one was. Now I get why.

The testing was done with a hallow cylinder with affected area of 7.22 square inches. So hydraulic psi x 7.22 = clamp force. There is minor variations in what oil is used, accuracies of torque wrench, and the person operating the tools and reading the gauge, but identical tools and conditions on all fasteners keeps it equal.
I used 2 different quality gauges, compared 3 different torque wrenches 2 of which were calibrated within the month and the 3rd was a bar torque wrench.
tests done in March of 2020, I got my first ASE Masters back in the 90’s- so proper technique was used.

I went through 4 main 10mm bolts, 4 12mm main bolts, 4 12mm head bolts, 2 10mm main studs, 2 12mm main studs, 2 12mm head studs. All tests were done twice.
Room for error in reading the pressure I would estimate as 5-10 psi, however any misreading was consistent in recording.

One of the gauges is calibrated in psi and force. The force listed on the spreadsheet is based on psi X 7.22 via excel formula.

Please everyone share this on other forums, Facebook, etc so anyone can use the ARP studs and can match the force applied from bolts so there is no added stress to block and not even require align bore. Or they can choose to exceed clamp force if building hot rod and can see to scale how much more force (stress) they are applying to the block.

ANYONE that sells stud kits is welcome to include this chart or duplicate information from this chart in your kits. Just remember ARP doesn’t acknowledge anyone selling 6.5 main stud kits, and I am not authorizing the selling either for legal purposes. I am only authorizing sharing the mathematical testing for comparison I did.

 

[ak diesel driver]

Email me a copy Will

 

[Will L.]

When my wife or son shows me how to email the spreadsheet, I will email it to myself and anyone interested. My computer skills are poor.

Something interesting is the head stud clamp force lower. Remember ARP did the testing and sells head studs and set the specs accordingly. My understanding is the TTY bolts clamp but yield, and if there is a cylinder over pressurization event the bolts already at yielding point will stretch. This lifts head, the gasket fails.
However the ARP studs have a failure (stretching point) far beyond that of the blocks capacity. So if you max the head studs to say 120ft lbs, the clamp for e equal to the highest point of the TTY bolt, that same over pressurization event will now either rip the threads from the block, or warp the block- as many have learned.

feel free to crank-em down. Just know the smaller increase of protecting the gasket comes at the risk of destroying the block.

I believe this is the same case with the main studs. Some of us have seen blocks with the threads ripped right out if the main webs. Some seen total web failure. I’ve said it before and will a hundred more times... I believe match the clamp force AT MOST. The way to extend block life (except serious high performance) is to lessen the stress in the weak by design main webs.

 

[Will L.]

Oh yeah, I mic’e the rigging before and after. No deformities occured, other than the 10mm threads getting damaged when it was over torqued. And the cold roll tests harder than the block material. So block threads would fail before the test rig.
Again I forgot to take many pics along the way. Here was a couple.

 

[n8in8or]

I just got a 2nd edition set of 1998 C/K service manuals. Here’s what it has for main cap bolt installation.

 

[Husker6.5]

Yup, that's exactly what my 2nd Edition 1998 GMT Service manual says!

 

[Will L.]

So to get the same applied force as the main bolts, and to actually lessen stress in the main webs we are afraid of cracking in optimizers or late production GM 6.5:
The 12 mm would be torqued to 72 ft lbs.
The 10 mm would be torqued to 23.5 ft lbs.

Silly thing- I have not yet spoke the the ARP engineers with these numbers and had any input to from them. I haven’t gotten close to set my crank in place yet, so haven’t movedd this to the next step. Really need to do this...

Keep in mind the torque given by GM generally doesn’t hit what their max really is, it’s a target. So a bit of additional force could be ok in theory.

 

[Husker6.5]

So your 12mm studs to 72 lb/ft would then be the same as taking the 12mm TTY bolts to 55 lb/ft + 90° additional turning for total clamping force?

 

[Will L.]

So your 12mm studs to 72 lb/ft would then be the same as taking the 12mm TTY bolts to 55 lb/ft + 90° additional turning for total clamping force?

No. Same as 48 ft lbs + 90° BUT looking again 75lbs is more accurate for clamp force. Sorry was rushed looking at it.

If using the older spec of 55 ft lbs + 90°, then arp nut would be 96 ft lbs.

So some of the failed mains using arp studs and the much higher torque specs may show why they failed- SO MUCH more clamping force was used.
I can’t say the higher specs given are wrong- but if less block stress is the goal then it is wrong. If a person has cap walk, then more may be in order- but a registered main cap (having the little side walls you have to smack the cap into) cap walk becomes nearly impossible.

I didn’t want to come out and say exactly “X” torque on arp until after talking to the arp engineers. I know they still won’t put their stamp of approval on any spec, but they may have guidelines they can point towards.

 

[Husker6.5]

I guess we had our 12mm bolts mixed up. 55 lb/ft + 90° are the inner 12mm bolts and 48 lb/ft + 90° are the outer 12mm bolts. You were talking outer and I was thinking inner in the posts above.

 

[n8in8or]

Hey @Will L. were you ever able to run your findings past the ARP engineers?

 

[Will L.]

No I haven’t yet, I need to. I will start that chase today, if no results because of being Saturday, I will follow on Monday. All next week is tied up so if it needs long phone call, I can do that the 18th.

 

[Will L.]

Updates:
ARP said they won’t approve anything less than max unless they do all testing themselves.
The concern is if stud isn’t stretched enough, vibration may allow a he nut to come loose.
They make the head stud kit themselves because they tested it out.
They found problems with damaged blocks (main webs) so don’t want to attach their stamp of approval because of that liability.

So they said IF we find the lower torque values that work- they would love to see them. They also wanted to know what options people were doing now for it. I told them about drilling and lock wire (aka safety wire). Also spoke about nordlock washers but would need to test with those for determining different torque requirements because of the added drag those style washers create.

Which leads me to the next part:
That certain member here read the other thread and contact led me offering the hydraulic test unit again! I said yes and he has it already going out today! So asap i will be in the shop testing.

I will be ordering different nordlocks tonight.

ANY OTHER TEST IDEAS - SPEAK NOW!

 

[n8in8or]

This is great news!!! Hey @Will L. can we help fund this so you aren't footing the bill alone?

 

[Will L.]

I am not spending almost anything because of the other member here that is loaning the tool- a second time now. So he is in for loaning a multi thousand dollar tool, and paying to ship it to my place- twice.
All I have is a shipping it two times, maybe half dozen arp stud/nut combos, a few new tty head bolts and main bolts, little steel and some time. Oh and a few nordlocks.

For folks wanting todo the lockwire method- hit me afterwards I could have ordered 6point main nuts for easier drilling.

 

[n8in8or]

I am not spending almost anything because of the other member here that is loaning the tool- a second time now. So he is in for loaning a multi thousand dollar tool, and paying to ship it to my place- twice.
All I have is a shipping it two times, maybe half dozen arp stud/nut combos, a few new tty head bolts and main bolts, little steel and some time. Oh and a few nordlocks.

For folks wanting todo the lockwire method- hit me afterwards I could have ordered 6point main nuts for easier drilling.

Well if you need some assistance, please hmu, I'm happy to help.

 

[ak diesel driver]

I'm for testing with loc-tite.

 

[MrMarty51]

Very interesting.

 

[MrMarty51]

I'm for testing with loc-tite.

Yeah, I would love to see those numbers.

 

[Twisted Steel Performance]

I still prefer splayed caps but it will be interesting to see the testing... except if threads are pulled out of the block..