6.9 IDI Build

[Tristan]

Good read Josh. Thanks for posting that.


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So according to those tests I should be safe to bump my 6.9 studs up to 100 or even 110 ft/lbs?




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[The_Josh_Bear]

So according to those tests I should be safe to bump my 6.9 studs up to 100 or even 110 ft/lbs?




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I'm no expert but that's what Justin's testing revealed. Based on his testing I wouldn't be shy about going to 105 or 110ft-lbs myself. Of course I'm no engine builder!

 

[Thewespaul]

If it tells you anything about the 6.9s, on the 7.3s I go to 145ft lbs with no issues

 

[WarNose]

Hopefully this will make you feel better:
https://www.ford-trucks.com/forums/1306098-head-bolt-stud-tech-thread-2.html
Post #16 is the torque-to-yeild test done by Justin @ R&D on the ARP 7.3 head studs. No stretch until 190+ft-lbs!!!

Edit: you are running a 6.9, doh. That's post #1 and no stretch until 130ft-lbs. Justin mentions that he would consider 120 safe for 6.9 studs.

Thanks for that link. That is good info. I called ARP and they said the studs should measure 6.120 inches. That is a little longer than what Justin measured. I'll just pull them and see what I get.

 

[The_Josh_Bear]

Thanks for that link. That is good info. I called ARP and they said the studs should measure 6.120 inches. That is a little longer than what Justin measured. I'll just pull them and see what I get.

Speaking of pulling torqued headstuds/bolts: what's the procedure for that?

 

[Thewespaul]

Remove in opposite sequence of the torque sequence. So instead of looking at the arp sheet and starting with the smallest number, you start with the biggest number and count down to one. As far how to remove them, I break them loose one at a time, then remove them with my little ugga dugga

 

[The_Josh_Bear]

Remove in opposite sequence of the torque sequence. So instead of looking at the arp sheet and starting with the smallest number, you start with the biggest number and count down to one. As far how to remove them, I break them loose one at a time, then remove them with my little ugga dugga

Ok but you wouldn't take each stud or bolt from torqued to totally loose in one step right? Like 1/2 turn loose on all then zip them out eh? Seems like so many are worried about messing up heads during torque down but nobody says anything about removal.

 

[WarNose]

They're removed and measured. Only 2 messured exactly 6.120". Five measured less, with the shortest being 6.115". The remaining twenty-seven studs were oversized, with the longest being 6.128". This was using a cheap Harbour Freight 8" digital micrometer that never returns to zero accurately. I checked it against my 5" standard and it measured between 5.002 and 5.004 each time. It was the only thing that I could get to measure over 6". But I also wonder how precisely the studs were manufactured to 6.120" to begin with. It seems like they must have had some variance to begin with. I measured the longest and shortest studs side by side and they are definitely different. The ARP rep said that he GUESSES that they would stretch .030 to .040 if they had on fact stretched. But he emphasized the guessing part. Justin's stretched only .002 somewhere over 110 lbs/ft.
He also said to make sure that the threads were still good. They are. Since I have some heavy overtime in my near future, I don't really have time to wait for new studs if I'm ever going to finish this motor. So I'm going to put these back in and hope for the best. What do you guys think?

I removed the studs in reverse order in 3 or 4 steps.

 

[Tristan]

I believe you want to follow the same steps that you use when torquing them, just in reverse. I still have the ARP instructions somewhere if you want I could send s picture.


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[Thewespaul]

Ok but you wouldn't take each stud or bolt from torqued to totally loose in one step right? Like 1/2 turn loose on all then zip them out eh? Seems like so many are worried about messing up heads during torque down but nobody says anything about removal.

I back the nut off by hand until its loose, then go back over them to loosen them back up by hand, then remove them. So id say the first pass is about a full turn, then once all of them are a full turn out I give them a half turn then zip them off.

 

[The_Josh_Bear]

I back the nut off by hand until its loose, then go back over them to loosen them back up by hand, then remove them. So id say the first pass is about a full turn, then once all of them are a full turn out I give them a half turn then zip them off.

Thanks Wes!

 

[The_Josh_Bear]

They're removed and measured. Only 2 messured exactly 6.120". Five measured less, with the shortest being 6.115". The remaining twenty-seven studs were oversized, with the longest being 6.128". This was using a cheap Harbour Freight 8" digital micrometer that never returns to zero accurately. I checked it against my 5" standard and it measured between 5.002 and 5.004 each time. It was the only thing that I could get to measure over 6". But I also wonder how precisely the studs were manufactured to 6.120" to begin with. It seems like they must have had some variance to begin with. I measured the longest and shortest studs side by side and they are definitely different. The ARP rep said that he GUESSES that they would stretch .030 to .040 if they had on fact stretched. But he emphasized the guessing part. Justin's stretched only .002 somewhere over 110 lbs/ft.
He also said to make sure that the threads were still good. They are. Since I have some heavy overtime in my near future, I don't really have time to wait for new studs if I'm ever going to finish this motor. So I'm going to put these back in and hope for the best. What do you guys think?

I removed the studs in reverse order in 3 or 4 steps.

Again I am no engine builder but if the threads are good, I would run them. Overtime or not it seems that any measured "stretch" is within the error range of the harbor freight device and not really worth the worry. At 100ft-lbs if they stretched they weren't ARP to start with, lol

 

[hacked89]

The previous owner torqued my 7.3 n/a to 130lbs. I'm sure you would be fine at 110 like others said.

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[IDIBRONCO]

I removed the studs in reverse order in 3 or 4 steps.

That's how I usually do it too. I'll just break them loose with about 1/4 turn the first time, then another 1/4 turn, then get them all loose, then I'll remove them. It sounds good this way, but sometimes one will get completely loose when the others are still tight. I just say "oops) and go on. I haven't had any issues.

 

[WarNose]

I'm finally at the point where I can pressure test the cooling system. I know Gary @icanfixall pressurized his to 30 or 35 psi on his 7.3. I don't want to go that high because my 6.9 heads don't have the coolant plugs between the heads and intake manifold like the 7.3s have. The gasket in that area looks like it xould easily leak so I sprayed copper gasket sealer there when I installed the intake manifold. I also made block off plates to test without the oil cooler. What would be a safe reasonable pressure for me to test to? I plan on filling with water and adding air to pressurize it.