Great experience
"Very good product"
Cummins
Shop All
SKU #: ARP-247-4204
MPN #: 247-4204
ARP CA625 Diesel Head Stud Kit 98.5-24 Dodge 5.9L/6.7L Cummins 247-4204
Description
Running a big single turbo or twins? Head studs are a must if you are pushing in excess of 45psi of boost. Why take the chance of ruining your day at the track or worse, doing permanent engine damage. With performance enthusiasts adding increasing amounts of turbo boost to diesel applications, ARP has provided an extra measure of security in the form of extra-strong head studs manufactured from the firm's proprietary Custom Age 625+ material that has a minimum rating of 260,000 psi tensile strength. They are engineered to provide the clamping force required to keep cylinder heads from lifting due to exceptionally high combustion pressures.
ARP also offers head stud kits made from ARP2000 (220,000 psi minimum) for the Dodge/Cummins plus Chevy Duramax diesel, Ford 7.3L Powerstroke diesel, and 6.0L Powerstroke. The stud kits include heat-treated chrome moly steel nuts (12-point) and parallel ground washers.
The studs are manufactured in ARP's Santa Paula, CA plant, with threads rolled after heat treat to provide optimum fatigue strength. They are centerless ground to assure perfect concentricity. The ends of the studs are broached to facilitate easy installation. This feature also enables the cylinder head to be removed in tight quarters.
Enter your zip and we'll see if installation is available.
- Request quotes from local installers at checkout
- Compare options and choose the best fit for your install
About WrenchConnected
WrenchConnected is an independent installation marketplace operating in partnership with Diesel Power Products.
How it works
After checkout, we route your vehicle info and part SKU to verified installation shops near you. Local installers review the job and submit competitive bids; you pick the shop you want based on price, reviews, and availability. Your name and email stay private until you select an installer.
Pricing
You pay for the bid from your preferred shop. The full amount is shown before you confirm — installers cannot add charges without your written consent. Payments are processed securely by Stripe.
Your privacy
During bidding, shops see only your service ZIP code, vehicle year/make/model, and the part SKU — not your name, email, or address. Only the shop you select receives your contact details after payment. We never sell your personal information.
More detail at wrenchconnected.com.
About ARP Bolts
More and more Diesel Power Products customers are running large single turbos or compound turbo set-ups. Many of these turbos are capable of upwards of 50PSI of boost pressure with the right fueling. At these pressures the stock head bolts on our light duty diesel trucks are prone to stretching which can lead to head gasket failure. Head to block sealing is critical and that's where ARP Diesel Head Studs come in.
You should know that ARP uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality. Then, each stud is precisely heat-treated to 220,000 psi. Following heat-treat, each stud is centerless ground to make it as close to perfectly concentric as possible. This procedure involves about ten very slight cuts and results in an exceptionally straight part. It's important to note that lesser quality studs are not even centerless ground”the material is thread rolled in bar stock form (mostly before heat-treat, when the material is easier to machine). ARP studs are thread rolled after heat-treat, which gives them about 1000% (that's ten times) better fatigue strength than those studs that are threaded prior to heat-treat. Because ARP studs are manufactured to such exacting tolerances, you will note that gaskets and cylinder heads literally glide into position and are perfectly aligned”something that won't happen with inferior quality head studs.
ARP HEAD STUDS AND HEAD BOLTSWhat really is the difference between a head stud and a head bolt you may be wondering. From the factory, all engines have head bolts. As nearly anyone has seen, a œbolt is a threaded shaft with a hexagonal head attached. These bolts thread into the respective hole and the bolt head is then torqued down on the head(s) with a great deal of the force being applied to the thread themselves. In contrast, a œstud is only the threaded shaft that is first installed into the block. Once the stud is installed onto the block, then the head gasket and head are placed. Finally, the head stud washer and nut are placed and torqued. Due to the change in orientation of where the force is applied, a head stud will not stretch as a head bolt will commonly do, as well as the superior metals used to make ARP head studs compared to stock head bolts.
SHOP ARP STUDS AND MORE FROM DPP!While most diesel performance enthusiast know ARP for their heads studs, they actually have a wide range of fasteners available that are far superior to their stock counterparts. From harmonic damper hardware to rod bolts, flexplate bolts, and so much more. With ARP, you can rest assured that youre installing the best hardware on the planet.
Blog
March 03, 2026
If you are shopping for a second-gen Dodge Ram, planning a build, or just trying to understand...
Read More12 Valve vs 24 Valve Cummins: What’s Right for You?
November 21, 2025
If you own a diesel pickup, your turbocharger is one of the hardest-working parts on the truck....
Read MoreHow to Tell If Your Turbo Is Starting to Fail (Without Pulling It Off)
October 30, 2025
Looking to buy a 2003-2004 Cummins 5.9? Learn the engine specs, common issues, upgrades, and what to...
Read More2003–2004 5.9L Cummins Buyer’s Guide: Specs, Problems & Upgrades
October 27, 2025
When it's time to replace head gaskets on your Power Stroke, there's more to the job than...
Read MoreOverview of Power Stroke Products' Solid Seal Head Gasket Kits
Overall rating: 5.0 / 5 from 6 reviews.
AI Generated Review Summary
Summary topics
Review topics: ["price","studs","insurance"].
Review highlights
Reviews
Came quick and seem to
"Came quick and seem to be working great!"
Good insurance for a 2nd gen swap
"Go for the 625's, never have to worry about your head gasket again. Best insurance for a 2nd gen swap."
Necessity
"I decided to get these because I wanted to make sure I wouldn't have any problems if in the future I decided to add more modifications."
Real ARP CA625s
"It took 3 of us 8 hours to install. Keep in mind the longer studs are for the exhaust side and you will need to notch the aluminum valve cover to clear the back stud no big deal."
Last review for the day and then I have to ge. . .
"Last review for the day and then I have to get back to work. Up for review is the ARP CA625 head studs. What can I say, has anybody ever received a bad ARP product?? I haven't. Now let's tackle the elephant in the room. . 1200$?? ya that's right and you don't even get ARP stickers or a T-shirt. . But what you do get is the best quality head stud in the world. For the record, the CA625 material used for these studs is used in a lot of other applications not just diesel. They have the proven history of success to go with them. They come in a box and are individually sleeved for protection, as you would hope. They have a stainless look to them so they are noticeably different than the 425's. If I recall right the torque settings are a bit higher also. Install factor is a bit higher due to the process itself. I give it a 4 on the hard to do scale. Not scary just take your time. ARP includes instructions and they say you can do the "one at a time" replacement of your factory bolts to keep from pulling the head off. With the absurd cylinder pressures in modified diesel engines, I would have to assume this is the one thing you wouldn't skimp on. Will the other work fine?? Maybe, but these are twice as nice for twice the price. . Install time will vary given what else you are doing. I was doing a cam swap so my time frame is irrelevant. Leaving the head on I would say 4-6 hours to do a quality job and no snafu's, replacing the head gasket way would double the time plus a trip to have your head milled and time to check your block deck for straightness. As for these. I have no complaints and no failures. ARP says if you use the moly lube they supply and follow the directions properly you can reuse them should you ever have the need to pull the head (like piston/rod swap later). Price is fair but hard to swallow lol. You won't be disappointed. Like so many other parts you really won't be able to appreciate the beauty because half of them are not in sight. You can rest assured that when your boost gage creeps on up into the 60's, these things have your back. . . 5 star approved. ."
Q&A
- So these won't fit a 21 ram, but the site says they will fit my 22 ram. Why?
- These head studs will fit a cummins from 1998.5-2024.
- Will these work for the 21 ram?
- Unfortunately they will not. I am pretty sure Cummins changed the headbolt size in 2019 with the introduction if the new 6.7 engine. -Sands
- Could be use on an almost stock truck? Looking to upgrade more parts later
- Yes, you can use these on stock or modified trucks!-TL
- When do you recommend using the ca625 studs over the regular studs? Just trying to justify the 3x more cost.
- 650+hp is when we will start to recommend the CA625 studs. - AW