SKU: 44455937608

ARP Head Stud/Bolt Kits

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Description

ARP Head Stud/Bolt KitsIt is for good reason that virtually every top professional engine builder relies on ARP Pro Series head studs for their all out competition powerplants. Simply stated, theres not a better stud setup on the market today. For openers, ARP uses a premium grade 8740 alloy that is rated far superior to aircraft quality. Each stud is placed vertically in special racks and precisely heat treated to 200,000 psi. This procedure ensures complete heat

It is for good reason that virtually every top professional engine builder relies on ARP Pro Series head studs for their all-out competition powerplants. Simply stated, there’s not a better stud setup on the market today.

For openers, ARP uses a premium grade 8740 alloy that is rated far superior to “aircraft” quality. Each stud is placed vertically in special racks and precisely heat-treated to 200,000 psi. This procedure ensures complete heat penetration and the results are far superior to those lesser quality studs from other manufacturers who just dump pieces in a basket and hope for the best.

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). 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 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 (a very common industry practice). It costs a lot more to do it this way, because it’s tough on tooling, but the results are well worth the extra effort.

You will also note that ARP offers specially undercut studs for several engines. This procedure (done only to the shorter studs) more equalizes the “stretch” of both studs, which makes for a more consistent clamping force – and one that compensates for head gasket compression when the cylinder heads are installed. This helps prevent blown head gaskets, and assures optimum engine sealing!

Premium quality heat-treated 8740 chrome moly steel head stud kits are available for most every domestic and import applications.

You won’t find a better quality stud on the market from any other source. Look for ARP stamped on each stud as your assurance of quality.

Clearly, ARP Head Stud/Bolt Kits are the best on the market today, and the favorite of leading professional engine builders in all forms of racing.

HIGH PERFORMANCE SERIES
High Performance head bolts are available with a reduced wrenching hex or 12-point and wide area flanged head that eliminates the need for valve train removal to facilitate cylinder head retorquing. All High Performance Series bolts are 180,000 psi (which is 15% stronger than Grade 8) and kits come complete with hardened parallel-ground washers.

PRO SERIES
All Pro Series bolts are cold-forged to ensure molecular integrity, heat-treated prior to thread rolling and machining, and are rated nominally at 200,000 psi. ARP Pro Series head bolt kits are application specific – designed for use with typically competition only components. These fasteners deliver superior strength and meet the ARP “ZERO defect – ZERO failure” quality standard. Hardened and parallel-ground washers are included with each kit to ensure even load distribution and accurate torque readings. All Pro Series head bolts have a reduced wrenching hex or 12-point head and wide area flange to eliminate the need for valve train removal for cylinder head retorquing and permits the use of larger diameter valve springs. Most applications have undercut short bolts that can help eliminate head gasket failures through providing more “stretch” to compensate for the additional compression of gaskets.

CUSTOM AGE 625 PLUS®

This newly formulated super-alloy demonstrates superior fatigue cycle life, tensile strength and toughness – with complete resistance to atmospheric corrosion and oxidation. ARP is the first to develop manufacturing and testing processes for fasteners with Custom Age 625+. Best of all it is less expensive and expected to soon replace MP-35 as the material of choice in the high strength, super-alloy field. Typical tensile strength is 260,000-280,000 psi.

 

Head Studs vs Bolts
On many street-driven vehicles, where master cylinders and other items protrude into the engine compartment, it’s probably necessary to use head bolts so that the cylinder heads can be removed with the engine in the car.

For most applications, however, studs are recommended. And for good reason. Using studs will make it much easier to assemble an engine (especially a racing powerplant which must be serviced frequently and quickly!) with the cylinder head and gasket assured of proper alignment.

Studs also provide more accurate and consistent torque loading. Here’s why. When you use bolts to secure the head, the fastener is actually being “twisted” while it’s being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. A stud should be installed in a “relaxed” mode – never crank it in tightly using a jammed nut.

If everything is right, the stud should be installed finger tight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. Remember, an undercut shorter stud will have a rate similar to a longer, standard shank stud. This provides a more even clamping force on the head. Because the head gasket will compress upon initial torquing, make sure studs and bolts are re-torqued after the engine has been run.

Shipping Notes
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Exchange/Return Notes
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SKU: 44455937608

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4.1 ★★★★★
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Tessy
Whiting, US
★★★★★ 1
Burned my already sensitive feet, too big
Color: Pink & Beige, Size: Medium/Large(fits size 8 to 11)
Feels icky, and the heat gets trapped and literally felt like my feet were being burned by these. The bottoms of these feel prickly and they are way too big. You have to sit still and cannot walk in them.
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Reviewed in the United States on April 22, 2026
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Ms. Mac
Waukegan, US
★★★★★ 5
Just as good as paraffin wax
Color: Pink & Beige, Size: Medium/Large(fits size 8 to 11)
I might prefer these socks over paraffin wax. They are comfy and very moisturizing. I use these socks once a week to keep the heels and soles of my feet moisturized between pedicures. I rinse with warm, soapy water then hang to dry. They are hard to walk in, but there's a saying printed in the socks that's says something to the effect of "take a break, stay off your feet" lol I love that as a reminder to put my feet up and relax
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Reviewed in the United States on April 9, 2026
S
Verified Purchase
SKI
Fort Morgan, US
★★★★★ 5
Love these!
Color: Pink & Beige, Size: Small(fits up to size 7)
Love these! As I write this review, I’m sitting in my recliner with these on. I have had other silicone socks in the past and would like to share a few of the things that I have learned. These fit great! The others were 2-3 sizes too big because you could not order a size. I wear a size 7 women’s shoe. I got the smaller size. I walked around my apartment in my old ones and they got kinda yucky. Now, I sit in my recliner, put them on and chill for a few hours. I now take them off and put in a ziplock bag so they stay nice and clean (no cat hair!). I use them once a week usually on Saturday or Sunday as I’m a working girl. Also, I use Auqaphor before I put them on and put cotton socks on after I’m finished. Your feet will be SO soft. This is not a one and done…I do this every week especially during sandal season! I know this was lengthy and I hope you got some tips.
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Reviewed in the United States on April 25, 2026
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Kelsey
Birmingham, US
★★★★★ 5
The dogs like it very much, it produces a lot of noise.
Size: Large, Size: Large
I’m rating this based on my dogs’ response to this toy – they absolutely love it, and it has seen more use without damage than any of their regular throwing toys. At the same time, unless you enjoy, REALLY ENJOY the sound of crunching water bottles, you may not like having this ball in the house. Pros: The rubber outer shell of the ball is durable, and can survive both chewing and pulling forces (as a note, my dogs do not concentrate on chewing - they use it more for play games). It’s big enough for my dogs to play tug of war with it, hooking their teeth in the mesh, and they since it bounces around if they drop or kick it, it makes the game more interesting than rope. They did crush the interior plastic, but they don't really seem to care. It’s much more engaging than a normal ball, and can be modified to hold treats, sticks, rope elements and other external bits, which my shepherd mix loves; he gets bored easily and frequently, and this can actually entertain him. Cons: This toy is loud, and produces repetitive crunching sounds. It is apparently really engaging to chew, and my dogs will produce the horrid plastic crackling up to half an hour at a time. If you let your dogs in and out, it would make a fine outdoor toy, but since I have a dog door, it migrates around to pretty much wherever the dogs are. I kind of hate it, but will probably buy another if they break this one since they enjoy it so much.
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Reviewed in the United States on October 17, 2016
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Verified Purchase
BakedN
Cuba, US
★★★★★ 5
Very durable and my Heeler's fave inside toy
Size: Large
My red Heeler loves these balls, second only to Tennis balls but she destroys those within minutes and they are outside only. This is her inside ball. She is hard on toys and has the strongest bite of any dog I've had (shepherds, collies, weimaraners, retrievers, Labs) yet these continue to last. She catches the ball, we play tug of war with it (she places it in hand hand and pulls only when I have a firm grip, she shakes it and flings it. The rubber outside even outlasts the water-bottle like plastic piece inside. Steps holds the ball with her foot and pulls on the rubber with her mouth, stretching it to sometimes twice its size. I pull while shes pulling. This thing gets abused daily and keeps on going. Its the most used toy and she brings it to me to play with every day. Each ball lasts about 6 months before the inside ball is toast and the outer rubber is finally starting to tear/break. which for me in an incredibly long time. If this ball is available to play, she wants it over all others. Shes NEVER gotten a piece off to actually swallow and that alone is worth the price.
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Reviewed in the United States on June 4, 2025

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