ARP Head Bolts.....torque to spec or a little more?
03-29-2011, 03:10 PM
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ARP Head Bolts.....torque to spec or a little more? A friend of mine told me that he goes an extra 5lbs of torque on ARP bolts.
Is this recommended? Hazardous?
Getting ready to install a set of heads on my Nitroused stock shortblock LS1 and want to make sure before I screw something up.
I'm just going with stock gaskets, etc.
Is this recommended? Hazardous?
Getting ready to install a set of heads on my Nitroused stock shortblock LS1 and want to make sure before I screw something up.
I'm just going with stock gaskets, etc.
03-29-2011, 03:24 PM
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03-29-2011, 03:51 PM
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Exactly, we seem to have a lot that wear their feelings on their shoulders. No harm intended, but I'm sure you gotta be pretty ******* smart to design torque specs for ARP. Probably went to school for a long time and studied your *** off. The torque specs being incorrect could bankrupt their company. Im not smarter about torque specs then ARP's people, neither are you, why play like we are. Sorry if I offended your delicate sensibilities 
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03-29-2011, 04:03 PM
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03-29-2011, 05:38 PM
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They re-ran preload tests a year or so ago and hence an increase. Remember, torque is the value by which you are measuring the preload (force) in the bolt/stud. The accuracy of this force is more important than the additional five lb-ft you are discussing. Friction is the biggest error in transforming a measured torque to a force value as this can change force by 40% done incorrectly. Also worth noting, ARP has released a new lube and this may again change the final value. They are striving for a consistant force, and altering the torque value will in turn alter the force. Best to verify directly with ARP.
You are also preloading the bolts/studs to a percent of failure, and increasing the torque value arbitrarily without knowing the force that is being applied is risking failure. The best thing you can do is use their values, use their lube and ensure that the studs, washers and nuts are correctly lubricated.
Also, accuracy of the torque wrench being used will make a difference and if you are unsure of the accuracy of your wrench you could be way high or low.
My final recommendation is that you are better off doing a re-torque after two heat cylces then overtightening. I found this to provide better sealing especially with Cometics. This is done by running the motor through two heat cycles then following the torque sequence one at a time backing off 1/8 turn and then re-tighten to final torque (only on the large bolts/studs).
You are also preloading the bolts/studs to a percent of failure, and increasing the torque value arbitrarily without knowing the force that is being applied is risking failure. The best thing you can do is use their values, use their lube and ensure that the studs, washers and nuts are correctly lubricated.
Also, accuracy of the torque wrench being used will make a difference and if you are unsure of the accuracy of your wrench you could be way high or low.
My final recommendation is that you are better off doing a re-torque after two heat cylces then overtightening. I found this to provide better sealing especially with Cometics. This is done by running the motor through two heat cycles then following the torque sequence one at a time backing off 1/8 turn and then re-tighten to final torque (only on the large bolts/studs).
03-29-2011, 06:01 PM
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Called ARP today.
My product sheet that came with the bolts recommends 75ft/lbs.
The tech @ ARP said that you can use the same assembly lube included with the bolts and torque an additional 5-10 ft/lbs for nitrous or boost applications. So it looks like 85 ft/lbs is what they'll get.
So I appreciate all of your input, and for the wise guys that had comments about "just do it like ARP says" this is why I posted the topic, because thier is a range, and it is important.
Glad I didn't just listen to you!
My product sheet that came with the bolts recommends 75ft/lbs.
The tech @ ARP said that you can use the same assembly lube included with the bolts and torque an additional 5-10 ft/lbs for nitrous or boost applications. So it looks like 85 ft/lbs is what they'll get.
So I appreciate all of your input, and for the wise guys that had comments about "just do it like ARP says" this is why I posted the topic, because thier is a range, and it is important.
Glad I didn't just listen to you!
03-29-2011, 06:03 PM
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They re-ran preload tests a year or so ago and hence an increase. Remember, torque is the value by which you are measuring the preload (force) in the bolt/stud. The accuracy of this force is more important than the additional five lb-ft you are discussing. Friction is the biggest error in transforming a measured torque to a force value as this can change force by 40% done incorrectly. Also worth noting, ARP has released a new lube and this may again change the final value. They are striving for a consistant force, and altering the torque value will in turn alter the force. Best to verify directly with ARP.
You are also preloading the bolts/studs to a percent of failure, and increasing the torque value arbitrarily without knowing the force that is being applied is risking failure. The best thing you can do is use their values, use their lube and ensure that the studs, washers and nuts are correctly lubricated.
Also, accuracy of the torque wrench being used will make a difference and if you are unsure of the accuracy of your wrench you could be way high or low.
My final recommendation is that you are better off doing a re-torque after two heat cylces then overtightening. I found this to provide better sealing especially with Cometics. This is done by running the motor through two heat cycles then following the torque sequence one at a time backing off 1/8 turn and then re-tighten to final torque (only on the large bolts/studs).
You are also preloading the bolts/studs to a percent of failure, and increasing the torque value arbitrarily without knowing the force that is being applied is risking failure. The best thing you can do is use their values, use their lube and ensure that the studs, washers and nuts are correctly lubricated.
Also, accuracy of the torque wrench being used will make a difference and if you are unsure of the accuracy of your wrench you could be way high or low.
My final recommendation is that you are better off doing a re-torque after two heat cylces then overtightening. I found this to provide better sealing especially with Cometics. This is done by running the motor through two heat cycles then following the torque sequence one at a time backing off 1/8 turn and then re-tighten to final torque (only on the large bolts/studs).
03-29-2011, 06:48 PM
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Called ARP today.
My product sheet that came with the bolts recommends 75ft/lbs.
The tech @ ARP said that you can use the same assembly lube included with the bolts and torque an additional 5-10 ft/lbs for nitrous or boost applications. So it looks like 85 ft/lbs is what they'll get.
So I appreciate all of your input, and for the wise guys that had comments about "just do it like ARP says" this is why I posted the topic, because thier is a range, and it is important.
Glad I didn't just listen to you!
My product sheet that came with the bolts recommends 75ft/lbs.
The tech @ ARP said that you can use the same assembly lube included with the bolts and torque an additional 5-10 ft/lbs for nitrous or boost applications. So it looks like 85 ft/lbs is what they'll get.
So I appreciate all of your input, and for the wise guys that had comments about "just do it like ARP says" this is why I posted the topic, because thier is a range, and it is important.
Glad I didn't just listen to you!
Actually, you did exactly what he told you to do, and did exactly what ARP told you to...
Am I the only one who noticed this? lol...
03-29-2011, 07:12 PM
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The first poster told me not to re-invent the wheel and just do it to spec. Had I listened to him I would be torquing to 75ft/lbs.
Anyway, no big deal, we're beyond that now.
03-30-2011, 02:39 PM
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Had I listened to you, I would have torqued to 75 ft/lbs.
The reason I came out on top was because I didn't listen to you, called ARP (which you never said to do) and the tech told me to go OVER SPEC by 10 ft/lbs for my application.
So how is it that I took your advice?
Anyway. Thanks to everyone for your help.
