Studs discussion
- Thread starter RescueF250
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webb06
Active member
The stud is pulling away from the block not pushing in to it.
dsberman94
Well-known member
iirc ARP's instructions also say to turn the studs finger tight into the block
Morgan@Midwest Diesel & Auto
New member
The problem is not that the stud pushes the bottom out the hole. They split on a casting line about 1.5" up. They only do it in two holes on each side of the block next to the lifter galley. It is thinner there and susceptible to cracking. The rest are good. I've got a few cracked blocks here to prove it.
Fwiw our pulling truck is torqued to 250 on all the holes except the four weak ones that are torqued to 225. All with arp's and the newest lube. Never used a drop of coolant. We have since been doing all of them that way and have not had one single issue to date.
Fwiw our pulling truck is torqued to 250 on all the holes except the four weak ones that are torqued to 225. All with arp's and the newest lube. Never used a drop of coolant. We have since been doing all of them that way and have not had one single issue to date.
dsberman94
Well-known member
which ones are the 2 weak ones? pics? i understand 4 are weak but only 2 per side and i assume they are the same on both sides. our instructions from ARP say 275. now thinking do all to 275 except for those weak ones at 250. opinions on this? this is on a 6.4 BTW.
Morgan@Midwest Diesel & Auto
New member
Yeah. The ones next to the lifter valley second from the ends. If you have the heads off and look you see the physically less material around those two studs on each side.
Give it a try, can't hurt. We run less # than that and haven't blown any.
You can see the two stud holes in this picture have noticeably less material.
Give it a try, can't hurt. We run less # than that and haven't blown any.
You can see the two stud holes in this picture have noticeably less material.
dsberman94
Well-known member
that is very noticable. thanks for the pic. i wouldn't have known what you were talking about without the pic until this weekend anyway since thats when were doing the work. might as well give it a try doing what i said. if you guys torqued a built pulling truck to less i can't see it being all that bad to do what i was saying.
drunk on diesel
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the tension is on the threads in the iron... if you pre-load them, you amplify it when you apply torque to the fastener
powerstrokedkid87
Active member
typically when we do them, make sure the bottom of the holes are cleaned out, run them hand tight in (no ratchets, or allen wrenched), and back it off slightly, works well from what we have seen so far. To each their own!
sootie
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as far as i can see, its a myth based on where the blocks crack.
Morgan@Midwest Diesel & Auto
New member
Ill repost this.
Once again not splitting the bottom of the hole.
They crack because of too much torque. I guarantee to I can take an arp with new line torque it too high and split a block every time. But only in those holes. 100% of the cracked blocks I see are cracked in the same spot. Only way to stop is is lower torque. I agree with not torquing the stud in the block, but it is not the cause.
dsberman94
Well-known member
So here's another question. Did you guys back pressure off the studs before going to the next torque level. I've read some guys do it but the directions say not to. Also what increments did you go up by. Use the directions increments or you went by some of your own?
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Yeah. The ones next to the lifter valley second from the ends. If you have the heads off and look you see the physically less material around those two studs on each side.
Give it a try, can't hurt. We run less # than that and haven't blown any.
You can see the two stud holes in this picture have noticeably less material.
funny you post this, i was actually asking a buddy who was doing hg's on a 6.4 today, about using less tq in the stressed areas. he knows nothing about the block cracking problems , but it makes sense to a person such as myself.
i'm intersted to see how the h-13 works, i have faith that this will be our better option, but no mathematical data or metalurgy to back up such statements. i just like the idea of less tq stress on the block. what say you ?
I am glad you asked that question cause I have seen a lot of different answers. I am going to throw my best GUESS at this cause I am interested to hear where I am wrong. Initially, the lower torque values may not be reducing the clamping force and ultimately stress on the block would be same cause the stud is stretching less so less torque on the stud with the torque wrench does not necessarily mean less clamping force. BUT because the stud would be less prone to stretching when at WOT, you may ultimately be able to apply LESS clamping force initially and get away with it compared to the standard APR 2000s because they would stretch a little more during WOT. Of course, the stronger stud will only help reduce the stress on the block if the manufacturer calcuated the recommended torque values to provide less clamping force than the ARP 2000s.
StockCar#10
Member
Heres the million dollar question.... whats the lowest torque anyone's torqued there studs to??
Morgan@Midwest Diesel & Auto
New member
Well here's how it is, it takes xxxx pressure (torque) on a 16mm stud (6.4 size) to achieve xxxx clamping force for the given stretch of the psi (tensile strength) of said stud material.
Let's say it takes xxxxx psi of clamping force over the 3.87 bore (6.4 standard bore size) and three different stud brands do it at three different torques. It doesn't matter what the spec is. The fact that the same size studs apply the same clamping force over the same area = same stress in the block.
Let's say it takes xxxxx psi of clamping force over the 3.87 bore (6.4 standard bore size) and three different stud brands do it at three different torques. It doesn't matter what the spec is. The fact that the same size studs apply the same clamping force over the same area = same stress in the block.
