BHG job questions....
- Thread starter KongGMC
- Start date
If you go ARP, get the studs. Plain and simple.
Putting those bad boys in was the best part of the whole head gasket repair for me.
Putting those bad boys in was the best part of the whole head gasket repair for me.
So I priced a set of the ARP's for my car on Horsepowerfreaks.com . It didn't say anything about studs but the picture of the "head bolts" was a picture of studs so I guess that's right. I'm wondering though, how do the studs work as opposed to using bolts?
KongGMC;992888 said:
Studs have better clamping /holing power then a bolts.. try this.take a peace of anything solid run a bolt and nut threw it. tighten the head of bolt as tight as you can...with a 6 inch wrench. then flip over and you will be able to tighten nut even more..there is alot more to it then just that... but studs work better then bolts 99% of time..
ebay and summit carry 7mgte head stud kits... i think i paid 129 from summit
This is what I think about the studs vs bolts. An expert could correct/confirm this...
With studs the force you put onto the torque wrench goes almost entirely into the vertical clamp of the head. The stud does not spin or move, the only thing that moves is the nut on top so you only have frictional forces from the washer's bottom surface affecting your torque.
With bolts, you have frictional forces from the bolt twisting through the block as well, so your clamping force is less precise.
With studs the force you put onto the torque wrench goes almost entirely into the vertical clamp of the head. The stud does not spin or move, the only thing that moves is the nut on top so you only have frictional forces from the washer's bottom surface affecting your torque.
With bolts, you have frictional forces from the bolt twisting through the block as well, so your clamping force is less precise.
Pretty much dead on
The nut does have friction mating with the stud threads, but it is less than what you see with a bolt. Both have friction where they mate with the washer. The use of moly is a huge factor in reducing friction. This is a good read (especially under "Using a Torque Wrench"):
http://www.arp-bolts.com/Tech/TechInstall.html
Note that ARP requires 5 tighten/loosen cycles before final torque to get a consistent friction coefficient.
The nut does have friction mating with the stud threads, but it is less than what you see with a bolt. Both have friction where they mate with the washer. The use of moly is a huge factor in reducing friction. This is a good read (especially under "Using a Torque Wrench"):
http://www.arp-bolts.com/Tech/TechInstall.html
Note that ARP requires 5 tighten/loosen cycles before final torque to get a consistent friction coefficient.
jdub;993041 said:Pretty much dead on
Note that ARP requires 5 tighten/loosen cycles before final torque to get a consistent friction coefficient.
Wait... What? What does that mean?
You didn't read the ARP link
The ARP recommendation is a bit over kill IMO...what I do is torque the ARPs down to 70 ft/lbs (4-5 passes), back off a 1/2 turn or so...go to 75 ft/lbs (2 passes), back off 1/2 turn...go to 80 ft/lbs (ARP stud torque spec, 2 passes). All using the TSRM pattern. I have never had a stud back off...I still do a re-torque at 5 or so full heat cycles on the motor though
The ARP recommendation is a bit over kill IMO...what I do is torque the ARPs down to 70 ft/lbs (4-5 passes), back off a 1/2 turn or so...go to 75 ft/lbs (2 passes), back off 1/2 turn...go to 80 ft/lbs (ARP stud torque spec, 2 passes). All using the TSRM pattern. I have never had a stud back off...I still do a re-torque at 5 or so full heat cycles on the motor though
KongGMC;993740 said:
When you are tightening them you're supposed to tighten to spec, then break loose, then tighten, then break loose.... etc. They say 5 times is what it takes.
*jdub, beat me to it.
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*smacks own back of head*... Okay so I did read the Fastener Retention Overview but I didn't look at the links on the left of the ARP site that talk about the actual process. So I did try okay. Thanks though. The ARP site definately looks like overkill though! So do you really have to take everything back apart and retorque the head bolts after the car has been running for a while? That sucks really bad man. Can you skip that process if you use OEM head bolts? Do you still have to torque, break em loose, retorque, break em loose, and retorque again with the OEM head bolts?
I've just never done anything like this before so it's all a learning process for me. THANKS A BUNCH TO ALL OF YOU WHO HAVE BEEN HELPING ME BY THE WAY!
Thanks though. The ARP site definately looks like overkill though! So do you really have to take everything back apart and retorque the head bolts after the car has been running for a while? That sucks really bad man. Can you skip that process if you use OEM head bolts? Do you still have to torque, break em loose, retorque, break em loose, and retorque again with the OEM head bolts? I've just never done anything like this before so it's all a learning process for me. THANKS A BUNCH TO ALL OF YOU WHO HAVE BEEN HELPING ME BY THE WAY!
You gotta keep something in mind about me...I'm pretty anal about this kind of thing. A LOT of attention to detail.
It's not as bad to do as you think...and, no, you don't have to take everything apart to do a re-torque after the motors been run a bit. All you do is use a breaker bar and just "crack" the bolts, then torque back to spec. IJ goes to 85 ft/lbs...I would go no more than that on a re-torque.
I would use the same technique as I posted above on OEM bolts...it's for getting a constant friction coefficient. And, you absolutely want to do a re-torque on them (even more critical than on ARPs).
It's not as bad to do as you think...and, no, you don't have to take everything apart to do a re-torque after the motors been run a bit. All you do is use a breaker bar and just "crack" the bolts, then torque back to spec. IJ goes to 85 ft/lbs...I would go no more than that on a re-torque.
I would use the same technique as I posted above on OEM bolts...it's for getting a constant friction coefficient. And, you absolutely want to do a re-torque on them (even more critical than on ARPs).
Okay, well I'll definately do it then. I just hate the idea of having to take crap back apart to retorque the head bolts. I don't remember for sure but is there enough room to get the intake cam cover off after you remove the throttle body or do you have to take off that first part of the intake as well? I mean I guess I'll find out once I get to putting it back together but I just thought I'd ask. And do you think you could reuse those gaskets or would you replace the gaskets again? I.E. valve cover gaskets, throttle body gaskets, and upper intake man. if it has to be removed as well.
Yeah...you can get both cam covers off with out removing the TB or manifold, no problem. And you can re-use the cam cover gaskets. If the cams are in the way for the re-torque, just rotate the crank with a 19mm socket and breaker bar...the cams will rotate too.
When you put everything back together, pay attention to all patterns (the cams have one too) and torque specs. RTV has to be applied in two locations on the top, front timing plate...it's in the TSRM. Forget this and you will have an oil leak
When you put everything back together, pay attention to all patterns (the cams have one too) and torque specs. RTV has to be applied in two locations on the top, front timing plate...it's in the TSRM. Forget this and you will have an oil leak
Even though I did a retorque, maybe jdub can clarify this.
2 things
1: I really don't see how a retorque can be effective on a 7M when all of the manifolds AND manifold braces (intake manifold brace, exhaust manifold brace, on GTE's the turbo brace and oil line) are still torqued to the motor. I remember IJ saying that there is enough "give" in the expansion of the metal to let this happen, but in reality I just can't see this as a good thing. Think about it, the head is being braced in 2 (3 on GTE's) locations, AND you are trying to clamp that head down, and we are talking microns here in units of measure (if it even moves at all) that the head is moving down while being braced.
2: What about the ARP moly on the threads when you assembled it? Run it a couple times (or in my case, 1000 miles), and there will be no moly left, especially if you use ARP studs, no more moly on those nuts, now there is used motor oil, so that means 85ft/lbs will be an undertorque, no?
I don't know maybe I just think to much.
2 things
1: I really don't see how a retorque can be effective on a 7M when all of the manifolds AND manifold braces (intake manifold brace, exhaust manifold brace, on GTE's the turbo brace and oil line) are still torqued to the motor. I remember IJ saying that there is enough "give" in the expansion of the metal to let this happen, but in reality I just can't see this as a good thing. Think about it, the head is being braced in 2 (3 on GTE's) locations, AND you are trying to clamp that head down, and we are talking microns here in units of measure (if it even moves at all) that the head is moving down while being braced.
2: What about the ARP moly on the threads when you assembled it? Run it a couple times (or in my case, 1000 miles), and there will be no moly left, especially if you use ARP studs, no more moly on those nuts, now there is used motor oil, so that means 85ft/lbs will be an undertorque, no?
I don't know maybe I just think to much.
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What happens is the aluminum head expands at a different rate than the steel block. This puts additional stress on the head bolts and creates movement between the head and block decks. ARP limits their head bolts to 75 ft/lbs of torque for this exact reason...studs do not have this limit. It is also why you want a very smooth RA for a MHG...you want to minimize the "sliding" effect on the MHG from the different expansion rates. A stock composite HG has this give built in.
The effect on head bolts is most pronounced, the heat expansion can actually cause the bolt to loosen. The effect is less with studs due to the way clamping force is transferred to the head. Doing a re-torque on bolts is a requirement IMO...you might be able to get away with not doing it on studs (especially used, heat cycled ones), but it's easy to do with no downside other than the time. I have seen studs back off one time...I do believe IJ has seen it too.
The Moly will still be there after 5 or so heat cycles...but, you are correct if you let it go for longer periods of time. The oil could very well seep into the threads. To be honest, I don't worry about this one too much
The effect on head bolts is most pronounced, the heat expansion can actually cause the bolt to loosen. The effect is less with studs due to the way clamping force is transferred to the head. Doing a re-torque on bolts is a requirement IMO...you might be able to get away with not doing it on studs (especially used, heat cycled ones), but it's easy to do with no downside other than the time. I have seen studs back off one time...I do believe IJ has seen it too.
The Moly will still be there after 5 or so heat cycles...but, you are correct if you let it go for longer periods of time. The oil could very well seep into the threads. To be honest, I don't worry about this one too much
I took my arp studs to 85lbs.
When I hit my 1k miles. I'm going to retorque them.
With the same wrench even.
Is it true that to do this you back them off 15lbs. And then cycle up to your goal torque spec?
Thanks.
When I hit my 1k miles. I'm going to retorque them.
With the same wrench even.
Is it true that to do this you back them off 15lbs. And then cycle up to your goal torque spec?
Thanks.
No need to be that precise...just back it off till it "cracks". Then I do it back to spec with 2 passes.
Use a breaker bar and not your torque wrench to crack em
(you probably know that...just for anyone else's benefit)
Use a breaker bar and not your torque wrench to crack em
(you probably know that...just for anyone else's benefit)
Sweet tip with the breaker bar.
That was the plan. I bought a kobalt torque wrench back when I did this.
I know I need a better one but this ones going to have to get it done for this build.
Thanks.
I was going to exceed the 1st torque of 85lbs. I'm thinking I'll go up to 90lbs.
Hopefully I will never have to do this to this car again.
She's screaming for the streets. Just in time for what was looking to be the 3rd summer of the build.
Now I get to tweak it. All the mod work has really payed off. I'm getting 3rd gear scratches.
That was the plan. I bought a kobalt torque wrench back when I did this.
I know I need a better one but this ones going to have to get it done for this build.
Thanks.
I was going to exceed the 1st torque of 85lbs. I'm thinking I'll go up to 90lbs.
Hopefully I will never have to do this to this car again.
She's screaming for the streets. Just in time for what was looking to be the 3rd summer of the build.
Now I get to tweak it. All the mod work has really payed off. I'm getting 3rd gear scratches.