ARP head bolts vs GM head bolts??
05-28-2003, 06:15 PM
#22
Re: ARP head bolts vs GM head bolts?? I would never recommend "torque to break"bolts 
Spend the money on studs and never worry again.I've changed cylinder heads 3 times so far and alway's smile that I do not have to thread into the block ever again.Have seen a few post's of people breaking bolt's in the Head
As for retorqing.Torque the heads down,then let sit over night,loosen and retorque.That should take care of the bolt stretch/gasket compression.
Spend the money on studs and never worry again.I've changed cylinder heads 3 times so far and alway's smile that I do not have to thread into the block ever again.Have seen a few post's of people breaking bolt's in the Head
As for retorqing.Torque the heads down,then let sit over night,loosen and retorque.That should take care of the bolt stretch/gasket compression.
05-29-2003, 01:41 AM
#23
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Re: ARP head bolts vs GM head bolts?? I believe that is one of the main reasons to go w/ARP bolts or studs is that they are reusable. Now like people have stated before this is only a recommendation, to not reuse the bolts. I was just reading a book the other day on rebuilding the Gen II motor, and it stated that you could probably re use the TTY bolts, but why risk the thousands of dollars that you spent on new parts, to save a couple of bucks. If I had blown a head gskt, I might just reuse the old bolts. But if I spent a couple thousand on heads and everything else, why risk it over buying some new bolts??? But like it's been said before, at the end of the day it's your wallet and your motor. 
06-08-2013, 11:45 AM
#24
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I know this is a crazy old thread but its the first one that pops up when you google "GM head bolt vs ARP" so I'll just post this here:
"Torque to yield" simply means tighten the bolt to its yield strength. Yield strength is the point at which the bolt begins to see plastic deformation. Any tension applied to a bolt causes it to stretch, even grabbing it by hand and pulling, but the deformation it sees there is called elastic deformation which means once the force is released it returns to its original shape. Different bolts have different yield strengths which is mostly dependent upon the specific alloy or heat treatment. Yield strength is generally measure in psi or ksi 200,000 psi = 200 ksi. In any case the higher the yield strength, the more brittle the bolt. There is another value that comes in to play and thats called ultimate tensile strength which is the point at which the bolt breaks and is obviously a higher value than its yield strength. When a bolt reaches and starts to exceed its yield strength the bolt actually work hardens until it becomes so brittle that it snaps. Torqueing any bolt to anything below its yield strength will not effect it at all and can be reused. Torqueing a bolt beyond its yield strength will cause it to become permanently stretched and more brittle and could be used again but the window from yield to ultimate is reduced and since a torque wrench doesnt measure the actual tension in the bolt, it becomes a guessing game as to how close it is to breaking. In short, its not a good idea to use any bolt that has already been torqued to its yield strength.
Another issue you have going on is that you never really know the exact yield strength of a bolt and no two bolts are the exact same. You would have to harness test each bolt to figure out its yield strength and then you would have to measure the tension on the bolt as you install it to know the exact clamping force. A torque wrench does not measure this, it simply measures the force required to rotate the bolt which in theory could calculate the tensile load but a little thing called friction becomes a variable that is not easy to quantify. This is why manufacturers use oil, to reduce the effect of friction in an effort to get a better idea of the tension on the bolt. But even with oil, friction is still there, and as stated above, you don't know the exact yield strength anyway so what are you torqueing to? Any bolt having a higher yield strength is capable of providing the same clamping force as a lower yield strength bolt and thus can be reused. This is why ARP sells bolts. I dont know their exact values but if they can guarantee that their torque specs never exceed the yield strength then you can reuse indefinitely. Having said that, the same can be said for the GM bolts but again, you never know if you have exceeded the yield strength so if you want peace of mind never reuse. As to which is better, its going to be the bolt with the higher yield strength because it takes more to stretch it so its less likely that the bolt becomes permanently deformed. Having said that, it doesn't mean everyone needs the stronger bolts.
"Torque to yield" simply means tighten the bolt to its yield strength. Yield strength is the point at which the bolt begins to see plastic deformation. Any tension applied to a bolt causes it to stretch, even grabbing it by hand and pulling, but the deformation it sees there is called elastic deformation which means once the force is released it returns to its original shape. Different bolts have different yield strengths which is mostly dependent upon the specific alloy or heat treatment. Yield strength is generally measure in psi or ksi 200,000 psi = 200 ksi. In any case the higher the yield strength, the more brittle the bolt. There is another value that comes in to play and thats called ultimate tensile strength which is the point at which the bolt breaks and is obviously a higher value than its yield strength. When a bolt reaches and starts to exceed its yield strength the bolt actually work hardens until it becomes so brittle that it snaps. Torqueing any bolt to anything below its yield strength will not effect it at all and can be reused. Torqueing a bolt beyond its yield strength will cause it to become permanently stretched and more brittle and could be used again but the window from yield to ultimate is reduced and since a torque wrench doesnt measure the actual tension in the bolt, it becomes a guessing game as to how close it is to breaking. In short, its not a good idea to use any bolt that has already been torqued to its yield strength.
Another issue you have going on is that you never really know the exact yield strength of a bolt and no two bolts are the exact same. You would have to harness test each bolt to figure out its yield strength and then you would have to measure the tension on the bolt as you install it to know the exact clamping force. A torque wrench does not measure this, it simply measures the force required to rotate the bolt which in theory could calculate the tensile load but a little thing called friction becomes a variable that is not easy to quantify. This is why manufacturers use oil, to reduce the effect of friction in an effort to get a better idea of the tension on the bolt. But even with oil, friction is still there, and as stated above, you don't know the exact yield strength anyway so what are you torqueing to? Any bolt having a higher yield strength is capable of providing the same clamping force as a lower yield strength bolt and thus can be reused. This is why ARP sells bolts. I dont know their exact values but if they can guarantee that their torque specs never exceed the yield strength then you can reuse indefinitely. Having said that, the same can be said for the GM bolts but again, you never know if you have exceeded the yield strength so if you want peace of mind never reuse. As to which is better, its going to be the bolt with the higher yield strength because it takes more to stretch it so its less likely that the bolt becomes permanently deformed. Having said that, it doesn't mean everyone needs the stronger bolts.
06-08-2013, 01:21 PM
#25
This post was a long one to skim through...Bottom line is there is nothing wrong with GM bolts. ARP has the benefit of being stronger and re-usable.
I can see why a GM dealer would re-use TTY bolts. Why would they care? It's saving them money and Corporate GM is paying the bills for warranty items, so the more they save, the more they make. If it breaks again, you will bring it right back for more repairs. A GM dealer and "GM" are not the same entities...so I wouldn't take what they say to the bank.
Anyone here see the video of the GM dealer installing the balancer on with a sledge hammer?
TTY bolts are just that, They are stretched to the point which they have clamping force, but stretched the bolt to a point where they will not return to the original length. You may experience a broken bolt or a lack of clamping force if you re-use them. Why risk it on something as critical as a cylinder head?
ARP bolts are torqued to 75% of the yield. They will return back to the original length and can be re-used.
If OEM bolts were as reliable and up to the task of racing, ARP wouldn't exist today...
I can see why a GM dealer would re-use TTY bolts. Why would they care? It's saving them money and Corporate GM is paying the bills for warranty items, so the more they save, the more they make. If it breaks again, you will bring it right back for more repairs. A GM dealer and "GM" are not the same entities...so I wouldn't take what they say to the bank.
Anyone here see the video of the GM dealer installing the balancer on with a sledge hammer?
TTY bolts are just that, They are stretched to the point which they have clamping force, but stretched the bolt to a point where they will not return to the original length. You may experience a broken bolt or a lack of clamping force if you re-use them. Why risk it on something as critical as a cylinder head?
ARP bolts are torqued to 75% of the yield. They will return back to the original length and can be re-used.
If OEM bolts were as reliable and up to the task of racing, ARP wouldn't exist today...
06-08-2013, 02:01 PM
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It also should be noted that the term "Torque to Yield" is a process, not a part. Any bolt can be "torqued to yield" even ARP but they use bolts with such high yield strengths that its not needed to go that high.
06-08-2013, 03:03 PM
#27
The gen 2 LT1 switch mid production maybe between 95 and 96 from standard SBC bolts to TTY and the bolts did change and the TTY ones have broken when guys tried to reuse them.
It is not complete bull, the fasterners are designed to yield, I am glad those who threw the dice on that got away with it but that doesn't mean the bolts are the same. If you tried to torque a higher strength bolt to yeild you run substantial risk of pulling threads or other damage.
Far as stretch, stretching is what we are doing to bolts when we torque them, that little bit to spring tension is what locks them in place.
It is not complete bull, the fasterners are designed to yield, I am glad those who threw the dice on that got away with it but that doesn't mean the bolts are the same. If you tried to torque a higher strength bolt to yeild you run substantial risk of pulling threads or other damage.
Far as stretch, stretching is what we are doing to bolts when we torque them, that little bit to spring tension is what locks them in place.
10-11-2017, 09:37 AM
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Wow. Searching for some different things and came across this thread at the top of a few searches. All I can say is wow.
I just want to say this, as a GM certified Master Tech who has worked at a few different dealerships, me nor anyone I have worked with reuse TTY head bolts. This is not a common practice in my field.
I personally would recommend going with something better, like ARP, once you see an increase in cylinder pressure. However I have had no issues with my build making 420rwhp plus 150 shot of nitrous on stock headbolts (I intended on taking it back apart so didn't spend the money upfront) so it's not like they're bad parts, just not to be reused.
I just want to say this, as a GM certified Master Tech who has worked at a few different dealerships, me nor anyone I have worked with reuse TTY head bolts. This is not a common practice in my field.
I personally would recommend going with something better, like ARP, once you see an increase in cylinder pressure. However I have had no issues with my build making 420rwhp plus 150 shot of nitrous on stock headbolts (I intended on taking it back apart so didn't spend the money upfront) so it's not like they're bad parts, just not to be reused.
10-11-2017, 09:55 AM
#29
Wow. Searching for some different things and came across this thread at the top of a few searches. All I can say is wow.
I just want to say this, as a GM certified Master Tech who has worked at a few different dealerships, me nor anyone I have worked with reuse TTY head bolts. This is not a common practice in my field.
I personally would recommend going with something better, like ARP, once you see an increase in cylinder pressure. However I have had no issues with my build making 420rwhp plus 150 shot of nitrous on stock headbolts (I intended on taking it back apart so didn't spend the money upfront) so it's not like they're bad parts, just not to be reused.
I just want to say this, as a GM certified Master Tech who has worked at a few different dealerships, me nor anyone I have worked with reuse TTY head bolts. This is not a common practice in my field.
I personally would recommend going with something better, like ARP, once you see an increase in cylinder pressure. However I have had no issues with my build making 420rwhp plus 150 shot of nitrous on stock headbolts (I intended on taking it back apart so didn't spend the money upfront) so it's not like they're bad parts, just not to be reused.
And how many mom and pop shops do you think actually change bolts while doing head gaskets?
Crazy old thread but still relevant. And maybe the one dealer was just still too new to LS engines.
10-03-2018, 09:14 PM
#30
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Ive re use them honestly like 5 or more times never had any isues and they were all high hp cars but they were all junkyard engines I wouldn't do it on a built engines or if I had a lot invested on the engine there like 50$ at autozone just my opinion
