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Toyota Supra 2JZGE/GTE 3.0L inline 6 (1993-98), Custom Age 625+ Head Stud Kit.
Don't remember where I found this info, but it might be helpful.MATERIALS USED IN THE MANUFACTURE OF CAP SCREW TYPE CONNECTING ROD BOLTS8740 CHROME MOLY: Until the development of today’s modernalloys, chrome moly was popularly considered a high strength material.Now viewed as only moderate strength, 8740 chrome moly is seen as a goodtough steel, with adequate fatigue properties for most racing applications,but only if the threads are rolled after heat-treatment, as is the standardARP® production practice. Typically, chrome moly is classified as aquench and temper steel, that can be heat-treated to deliver tensilestrengths between 180,000 and 210,000 psi.AERMET® 100: With a typical tensile strength of 280,000 psi, Aermet100 is a new martensitic super-alloy that is stronger and less expensivethan the super-alloy austenitic materials that follow. Because it is capableof achieving incredibly high clamping loads, it is ideal for short butextreme environments like top fuel, funny car and some short trackapplications. Although Aermet 100 is a maraging steel that is far superiorto other high strength steels in its resistance to stress corrosion, it mustbe kept well-oiled and not exposed to moisture.ARP2000: An exclusive, hybrid-alloy developed to deliver superiorstrength and better fatigue properties. While 8740 and ARP2000 sharesimilar characteristics—ARP®2000 is capable of achieving clamp loadsin the 215,000-220,000 psi range. ARP®2000 is used widely in shorttrack and drag racing as an up-grade from 8740 chrome moly in bothsteel and aluminum rods.
Stress corrosion and hydrogen embrittlementare typically not a problem, providing care is taken during installation.L19: This is a premium steel that is processed to deliver superiorstrength and fatigue properties. L19 is a very high strength materialcompared to 8740 and ARP®2000 and is capable of delivering clamploads in the 230,000-260,000 psi range. It is primarily used in short trackand drag racing applications where inertia loads exceed the clampingcapability of ARP®2000. Like most high strength, quench and tempersteels—L19 requires special care during manufacturing to avoid hydrogenembrittlement. This material is easily contaminated and subject to stresscorrosion. It must be kept well-oiled and not exposed to moisture.MATERIALS USED IN THE MANUFACTURE OF CAP SCREW TYPE CONNECTING ROD BOLTSINCONEL 718: A nickel based material that is in the high temperature,super-alloy class, it is found to be equally suitable in lower temperatureapplications.
This material delivers tensile strengths into the 220,000 psirange and exhibits improved fatigue properties. Best of all, Inconel 718is completely immune to hydrogen embrittlement and corrosion.ARP3.5 (AMS5844): While similar to Inconel 718, these super-alloysare found in many jet engine and aerospace applications where heat andstress attack the life of critical components. The high cobalt content ofthis alloy, while expensive, delivers a material with superior fatiguecharacteristics and typically tensile strength in the 270,000 psi range.The immunity to hydrogen embrittlement and corrosion of these materialsis a significant design consideration.
These materials are primarily used inconnecting rods where extremely high loads, high RPM and enduranceare important factors—Formula 1, Winston Cup and CART applications.CUSTOM AGE 625 PLUS®: This newly formulated super-alloydemonstrates 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 fastenerswith Custom Age 625+. Best of all it is less expensive and expected tosoon replace MP-35 as the material of choice in the high strength, super-alloyfield.
Typical tensile strength is 260,000 psi. So you know that if you plan on doing the head gasket repair yourself, you'll have to fix the stripped head bolt holes in the block. Forget about helicoils or threaded inserts. There are all kinds of kits on the market. But nothing even remotely comes close to the SureGrip Stud Kit designed and developed by Northstar Performance.These one piece CNC machined and heat treated studs completely eliminate the need for any type of threaded insert- the repair is the stud itself.
There is a full 2 inches of thread gripping in the block- the most of any Northstar repair kit- and best of all it's a one piece repair.The problem with threaded inserts is this: threads by nature are angled in a way that when you go to torque the head bolts down, it expands the insert in diameter. Sometimes when the insert expands in the block, the block cracks, or the insert expands enough to let the fine-thread M11 bolt slip over inside the insert. This is completely eliminated with the SureGrip Studs. Also when you go with these studs, the torquing is now done from on top with a nut (steel on steel) rather than twisting a bolt under load into the aluminum.You drill the holes in the block, tap them, and then install these studs. Then install the gasket, head, and secure with the special washers and nuts included in the kit.
It's that simple. Stronger than stock and more durable.Our kit may not be the cheapest fix on the market- but it's the best. Nobody wants to do this job twice on the same car. We are the only company to offer a repair for the Northstar that stands behind it so well, that if your head gaskets fail within one year, send us the studs back as well as the rest of the kit and we will refund your money. Nobody else trusts their repair method enough to do this. Give your car all the wide-open-throttle you want after installing our studs and new gaskets- you won't blow the gaskets again!These studs have been tested and proven on over 485 engines to date with 0 failures.
General Motors and Cadillac technicians who have used our studs swear they would never use anything else again!To order, call 1-888-800-9470 or use the form below. You can also send email toOrder Your Stud Kit:93-99 Northstar 4.0/4.6 Full Kit- $549.0 Northstar 4.0/4.6 Full Kit- $549.001 Set of Studs, Nuts, Washers (1993-1999)- $335.001 Set of Studs, Nuts, Washers (2000-2005)- $335.001 Set of Studs, Nuts, Washers (3.5 Liter V6)- $295.00Okay, perhaps they can be machined, these guys do, and at their prices, perhaps you do prefer to make your own. I've made zillions of bolts and studs over my career. Most were made to very high standards, supported by third party inspection, the full range of metallurgical controls, etc and even a few with rolled threads. I more than paid my dues making high confidence threaded fasteners.Trust me on this. The very best bolt you can make on a machine tool of certified material heat treated in the finest facility will still come up short of the strength and reliability of a factory made Grade 8 automotive bolt.
Production fasteners have the advantage of statistical process controls, chipless manufacture, and continuous heat treating, not to mention daily tests to destruction of samples taken from the run of production. The relaibility of a large lot manufacturing process has every advantage over a willing, dedicated, highly skilled guiy in a home shop or even in a well equipped job shop with conventail cutting tools. Those are facts of life even arrogant old bastards like me have to acknowledge.I strongly suggest you buy factory bolts and be dome with it. They really are superior.
I want to fabricate head studs for my 98 Cadillac Northstar engine and was planning on 8740 chrome moly. I have a few questions however. Is this an appropriate material or is there something better suited?
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How should I heat treat for the best strength? And should I cut the threads after heat treatment?my answer to this is DON'T, vehicle manufacturers go to great lengths to design certain features into cylinder head bolts of engine studs. You can more often than not buy uprated studs and bolts from reputable tuning companies for a reasonable cost. As an amateur ( I make that assumption) you will not be able to heat treat and choose the right materials in the fist place. All steels are NOT alike.Just bite the bullet and get the right ones.Ian. The SureGrip studs from North Star Performance are the only replacements known right now to not fail at a later time.Looks like the problem is with the female threads, not the bolts.
If the anchors loosen/yield, the bolts could then see varying stresses, which are a requirement for fatigue cracking.I have never seen a fractured head bolt that screwed into a cast iron block, and that means a LOT of bolts. But most of my involvement was with SBCs and BBCs-dunno about Ford stuff.Sounds like one more factory design screwup. At least the clown engineers who spec'd those stupid left-hand threads for the wheels on the left side of lots of Chrysler and some GM cars didn't cause failures. DO NOT use anything except factory head bolts/studs! Cylinder head to block sealing is one of the most challenging interfaces in a modern engine. Obtaining a seal that will remain sealed over a range of temperatures and pressures for a long service life is anything but a trivial matter.
There are many design attributes to these fasteners, and not all are readily apparent. The likelihood that you will get these deceptively simple looking fasteners right is no greater than that of these shade-tree shops that offer 'performance' parts that usually are anything but, if you define performance as working properly for a long service life.I would especially avoid ARP, as I have had bad luck with their products before. I learned a lot more than I wanted to about cylinder head sealing as a result of that bad choice of parts, and is why I would never use anything but properly engineered OEM parts for critical applications.The Northstar is a complex engine but robust and reliable if properly maintained. If you use appropriate parts and sweat the details, including but not limited to following the approved service procedures scrupulously, you should make a satisfying repair.Steve. DO NOT use anything except factory head bolts/studs! Cylinder head to block sealing is one of the most challenging interfaces in a modern engine.
Obtaining a seal that will remain sealed over a range of temperatures and pressures for a long service life is anything but a trivial matter. There are many design attributes to these fasteners, and not all are readily apparent.
The likelihood that you will get these deceptively simple looking fasteners right is no greater than that of these shade-tree shops that offer 'performance' parts that usually are anything but, if you define performance as working properly for a long service life.I would especially avoid ARP, as I have had bad luck with their products before. I learned a lot more than I wanted to about cylinder head sealing as a result of that bad choice of parts, and is why I would never use anything but properly engineered OEM parts for critical applications.The Northstar is a complex engine but robust and reliable if properly maintained.
If you use appropriate parts and sweat the details, including but not limited to following the approved service procedures scrupulously, you should make a satisfying repair.SteveSo you're saying that problems with the factory setup rarely happen? What kind of problems did you have with ARP stuff? Benesesso,I rebuilt an Olds diesel once, and those are some seriously loaded head bolts. I had replaced broken bolts before on other engines and didn't want any problems. An acquaintance was a Chevy truck engine development guy and he recommended the ARP stud kit, which as I recall cost quite a bit more than the original bolts.I installed the studs, which were quite a bit larger in diameter than the bolts, thinking I was really doing something. The engine ran great for all of 500 miles, at which point I started getting compression in the coolant again. Took everything apart and checked the flatness of the heads and block (again) and even took the heads to a head reconditioning shop, where they were magnafluxed and judged fine.I thought of what could possibly be causing the problem, and investigated many potential issues, e.g.
The studs had coarse threads to mate to the block, but the nuts up top were fine thread. ARP recommended the same torque as the service manual. Was I getting greater mechanical advantage (20 tpi vs. 13) due to the fine thread, and crushing the head gasket? I called ARP and they were completely uninterested in offering any help. I asked them, 'How did you determine the head tightening torque?' And all they would say is, 'tighten the nuts to (I think) 140 ft/lbs' and offer nothing more.I wasted tons of my time and that of cylinder head sealing engineers and fastener lab engineers before hitting on the answer.
The studs, being larger in diameter than the bolts, would require an excessively high tightening torque to obtain the stretch needed for proper sealing. As i say, I learned a lot more than I bargained for on that project.The fix? I pulled those damn studs and threw 'em away. I replaced them with the correct bolts and drove the car for nearly 100K miles before I sold it, and last I heard it was still chugging along.My opinion is, you have to be extremely leery of anything with the term 'racing' in it. Racing implies an engine that will be horribly abused for several hundred revolutions and then spray itself all over the pavement at the end of a quarter mile. There's nothing in that equation that is of any use or interest to me!
I wouldn't trust 'racing' parts to worn-out farm machinery.Stevebtw, I am not implying that every engine design is a good one. Plenty of bad examples come to mind, from all kinds of makers. The Northstar is a controversial engine because it is very complex and is not something you would want to do much repair work on. Repairs that are simple on other engines, e.g.
Starter replacement or oil pan resealing, are big deals on the Northstar. That said, it performs well, it's economical on gas for its power and the engine itself is very reliable. If there are horror stories about Northstars, I would venture to guess that most of them were caused, or at least exacerbated, by unqualified or careless mechanics.