We are often asked which is better, cylinder head studs or bolts.  The answer, invariably, depends on the installation. 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 service frequently and quickly!) with the cylinder head and gasket assured or 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. Because the head gasket will compress upon initial torqueing, make sure studs and bolts are re-torqued after the engine has been run.

It is for good reason that virtually every top professional engine builder relies on ARP 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 manufacturer who just dump pieces in a basket and hope for the best.
Following heat-treat, each stud is centreless 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 centreless 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 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, they are the best on the market today, and the favorite of leading professional engine builders in all forms of racing.

All Pro Series ARP2000 studs are centreless ground, heat treated prior to thread rolling and machining, and are nominally rated at 220,000 psi. These fasteners deliver a 25% increase in tensile strength over the OEM head bolts.