Head studs: ARP or A1

[tony597fitter]

Good info Comp!
I forgot about the 14mm studs actually weaken the block.

[triton]

I think both are quality products. I have 14mm A1 head and mains and my head is torqued to 155lbs. I haven't hit any really high boost numbers though... 55psi is the most it's seen. I've yet to have a problem.

It's a matter of... do you like Ford or Dodge ? Oreo's with white on the outside instead of inside ? I'm sure both companies will back their product equally

[triton]

Originally Posted by tony597fitter

Good info Comp!
I forgot about the 14mm studs actually weaken the block.

If it's done right... you don't take out enough to worry about.
You can bet most of the high hp pulling trucks are running 14's

[MKoth]

Originally Posted by triton

If it's done right... you don't take out enough to worry about.
You can bet most of the high hp pulling trucks are running 14's

They also may be using a block filler, which makes the block much stronger.

[COMP461]

Exactly Filling the block is not a viable option with 99.9% of the people on these sites.
This 14 mm stud deal, is one of the Band-Aids used in the past.

ARP stepped up and produced the New Age 625 stud, now there is no reason to have to drill and tap a block, and ream the heads out to fit this larger stud. When I first started development work on the B series Cummins, I talked with the engineers at ARP about larger studs , and even looked at 9/16 studs , why even go with metric stud , heck this is America and we should all be just as confused over fractions, A 9/16 a stud was just a little larger then 14mm and was less expensive , due to the fact that it’s a common stud size.


ARP’s engineers came back with some interesting facts after looking at the block and the clamping loads that were possible with a viable option. The answer was Custom New Age 625 material that they used in their formula one and Top Fuel studs. This material was not susceptible to hydrogen embitterment that H11 tool steel suffers from. The problem is that on the Cummins the studs are exposed to a continuous environment, which allows the studs to be exposed to water, this micros pits the studs and degrades the tinsel strength

One more thought, people wanting to hop up their truck should make a realistic plan of what they really want in terms of performance from their truck. A Realistic goal is important, that encompass budget, whether it’s to be a true daily drive who’s going to drive it, and who can fix it when it breaks.


A good plan will always start with basic building blocks and works to this goal. Don’t start with the biggest flashest parts, because the results will be a broken pile of parts.



Like the gas guy that bought a 850 holly double pumper for his almost stock small block, where a 600 vacuum secondary carburetor would have worked a lot better.

Seek out the guys that will lay out a plan , and stick to it !!!!!!!!

[Billysgoat]

FWIW Astro, Greggy Poo here is a site vendor who does sell ARP products. He might have even seen one or two get used He does know a few things worth listening to though, I didn't know about the effects of water on the stud material.

[COMP461]

why thank you.
I do try to take the needs and concerns of the diesel community to ARP, working very close with the engineers to produce any product needed. If any one has an new idea, or a product related problem. Give me a Shout.
When the need for a better fastener, to achieve combustion containment in the B series was being discussed, the 14 mm stud seemed to be an easy fix, and a 9/16 studs was even easer.

The engineers at ARP took an educated look at the block structure of the 5.9 and the clamping loads as opposed to the block distortion caused by a larger stud. And the answer was a NEW AGE 625 12 mm stud. This stud will develop the same or greater clamping loads as a 14 mm studs and removed no material from the block, or head.

[justinp20012500]

If 14mm studs torqued to 155 lbs/ft distort the cylinders, would new aged 12mm torqued to the same torque also distort the cylinders?

[RacinDuallie]

Originally Posted by justinp20012500

If 14mm studs torqued to 155 lbs/ft distort the cylinders, would new aged 12mm torqued to the same torque also distort the cylinders?

Justin when installing 14's you are drilling and removing precious block material which is one of the causes for bore distortion....

In any case it's best to hone the cylinders with a torque plate while the studs are in place, thus putting the bore under clamping distortion.....

[justinp20012500]

Originally Posted by RacinDuallie

Justin when installing 14's you are drilling and removing precious block material which is one of the causes for bore distortion....

In any case it's best to hone the cylinders with a torque plate while the studs are in place, thus putting the bore under clamping distortion.....

I understand the work it takes to install 14mm studs. And I firmly believe the torque plate is the only way to go.

But my questions is the increased clamping by the stonger stud. Will there be distortion?

Ask Maddog about too much stud torque and no stretch.

[KingS]

I'm not sure of all the talk about weakening the block when going to 14mm how is this happening? I understand you have to drill and tap the holes but come on it is a 2mm different and that is in diameter unless I'm thinking wrong not in width which in return is about the equivalent of you are drilling out the threads and minute amount more then threading it. I'm just asking for as of weakening the block I haven't seen any that have been weakened and failed my self so what is it that actually happens?

[Timbeaux]

My $2.89 headbolts seem to be doing well at 155+ Ft/lbs.

Greg, while I do agree that the reusability factor of studs is a good thing, they are hardly "necessary" for big power.

[COMP461]

The Cummins block holds the head on with the deck service. The amount of material that is available under the deck is not as generous as one might think; ARP had several blocks sectioned to do this engineering study. And the educated opinion of the fasteners engineers study was , the distortion was greatly increased by a larger stud. If bigger was the answer, then ARP would have used a 9/16 stud which was a little bigger, and commonly available with out all the added expense.

This is one of the reasons that ARP is the undisputed leader in racing and high performance fasteners. The do their engineering home work. There must be a reason that 99 % or all NASCAR engines are ARP and 100% or top fuel and top fuel funny Cars are ARP.

If you are going to bore or hone a Cummins, you must use a torque plate, the block will move all over the place, if you don’t. S&T Steel the people do the watejet work on all my projects make these torque plates, and they also rent them to use on your projects. 940 851 8055 Stan or Mat Thomas

[Diesel Freak]

I agree, the ammount of deck material in a Cummins block is dissapointing. Kinda sad IMO.

Installing 14mm studs brings the stud closer to the bore, and thus causes more distortion when loaded.

Just currious about Hydrogen Imbrittlement. At what temperature does it become a problem? What is the mechanism under which it occurs?

Is it really an issue on an engine?

[Diesel Freak]

A good read on Hydrogen Imbrittlement.

IMO, on these engines, it's not a huge issue especially if you are using a 50/50 mix on your coolent. Even with 100% DI Water, the H11 studs would still last years as other components would fail first from excessive corrosion.

http://stinet.dtic.mil/cgi-bin/GetTR...c=GetTRDoc.pdf

[Diesel Freak]

One more thing. If the health of the engine is good (ie, head gasket is holding all fluids where they should be) the studs should not be in contact with any water.

[Schoust]

I have talked with several people that are making a whole lot of power with a simple O ring Job and head bolts. From what I have been told it's all about the preperation........