5.9 24 valve head studs

JEWING3227

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Sep 17, 2016
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Its not my intention to open a can here. Looking for solid info on Ontork head studs users and how they are holding up. It's apparent they are being used as they can't keep up with supply/demand it appears. At $700 for a set, they look to be a secondary option to ARP 625 studs.

In a sense I want to try these out since I'm on the prowl for studs and a bigger single BUT I can't seem to find any user info out. Maybe that should be a clue.


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Get the UTS numbers from them.

425's is a good secondary to 625's, but UTS is what you need to compare.

Also, you have to trust them at their word on UTS, or do lots of testing yourself.
 
Have you looked into extreme studs? I'm not sure if they make them for your application or not.
Just be careful when you look them up.
 
Get the UTS numbers from them.

425's is a good secondary to 625's, but UTS is what you need to compare.

Also, you have to trust them at their word on UTS, or do lots of testing yourself.
Not sure about the UTS number but here is a little info from SPE's site...

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UTS is Ultimate Tensile Strength, which is what that 268,000ksi number reefers to.

I lose faith in them when they say it's 268,000ksi, when they mean PSI. KSI = 1000*PSI.

625's are 260,000psi.
 
I've heard the portion of the stud above the head is 13mm compared to 12mm on the 625's.

The portion in the hole is still 12mm on the ontork.

This would appear to mean a larger nut which mean more clamp area if you will. I'm pretty sure these Ontork studs do not use a washer like the 625's either.

One a side note and note that it really means much, there is video of these studs being torqued to over 300 ft lbs and not breaking. I understand fully this is simply a test and not recommended.

Appreciate the conversation so far!

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I've heard the portion of the stud above the head is 13mm compared to 12mm on the 625's.

The portion in the hole is still 12mm on the ontork.

This would appear to mean a larger nut which mean more clamp area if you will. I'm pretty sure these Ontork studs do not use a washer like the 625's either.

One a side note and note that it really means much, there is video of these studs being torqued to over 300 ft lbs and not breaking. I understand fully this is simply a test and not recommended.

Appreciate the conversation so far!

That washer is important. A cast head is very soft compared to a hardened washer. You take the washer, put a lubricant on it, and lube your threads, and you'll get a much more precise torque. Without that, you'll get embedment into the head and you'll get a torque that relates to cutting into the material and the stretch/clamping load of the fastener, instead of just the clamp load.

It doesn't matter much if it's 13mm in the center. Your stress riser is going to be at the start of your threads, which is 12mm.

The 300ftlbs comment by them is dependent on the pitch. What you want to know is the UTS. And like stated before, they share that, I just don't know how much faith I have in it if they're claiming it's over 1000 times stronger than ARP's. :Cheer:

Has anyone used these in a higher HP setting?
 
I'm not sure of who is using these. I've been assured by Dan Snyder at SPE that these studs are used in high powered pulling trucks. These fasteners started out being used by the powerstroke crowd and he purchased the company Ontork and now there made for the Cummins crowd. I just can't seem to find anyone using them.

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Kinda looks like the extreme studs
Not sure bud. They look similar to Haisleys L19 studs, or to me anyways.

Not being able to find info from buyers has me leaning more towards no BUT then comes the "sold out" part mixed with the good tensile strength and I'm back at possibly.

I'm guessing you've never heard of or had dealings with these studs?

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A friend of mine got these to replace his ARP2000's. The 3rd one he went to put in broke off flush in the block with less then 100ft/lbs. Snyder' took care of him at least with a new set and also said they had never saw one fail.

Unfortunately the truck hasn't ran since for other reasons not at all related to the stud breaking so I couldn't say how the studs work. His truck is an 04 w/ a single S475.
 
Hey bud, thanks for the info. Bad to hear it snapped but great he was taken care of.

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It's not like nobody's ever snapped an Arp though

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It's not like nobody's ever snapped an Arp though

But how many have snapped them while installing properly and to the correct torque? I think with ARP, you're paying not just for a fastener, but also their manufacturing repeat-ability and quality control.

And unless you're personally doing testing at a decent sample size, the numbers a company displays is only as good as their word. I doubt a lot of these smaller companies have the time/money/resources to do a full validation run.
 
Well the one I had read was from lavon, so I assume he installed them correct.

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Well the one I had read was from lavon, so I assume he installed them correct.

I'm not saying he doesn't know what he's doing, but it wouldn't surprise me if he was overtorquing them either. Did you ask him, or are you assuming?

Also, I'm not saying ARP is the end all, be all. I'm just saying that when it comes to fasteners, I'd be a little nervous tossing in some unknowns.
 
it wasnt a conversation between us. i was reading through his old post's on here and seen it.

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