Ok ARP 7.3 Stud detail time....


These are the 8740 190Kpsi bulk studs that you get through Typ4 or R&D....

7.000" @0ft/lbs
7.014" @90ft/lbs
7.015" @100ft/lbs
7.017" @110ft/lbs
7.019" @120ft/lbs
7.020" @130ft/lbs
7.022" @140ft/lbs
7.023" @150ft/lbs
Check- No stretch- 7.000" @0ft/lbs
7.023" @150ft/lbs
7.023" @160ft/lbs
7.026" @170ft/lbs
7.028" @180ft/lbs
Check- .005" stretch- 7.005" @0ft/lbs
7.028" @180ft/lbs
7.031" @190ft/lbs
7.038" @200ft/lbs

Got 1 click at 210ft/lbs of torque, and then it just kept turning...

By these results, I would say that its plenty safe to go to 160ft/lbs without stretching the stud, and probably up to 180ft/lbs if you really wanted to chance it.

I wanted to test the 7.3 head bolt tonight, but just didn't feel like it, so Ill do that tomorrow along with the 9/16" head stud.

 

Hmmm that is interesting. Thanks for all the updates and research! You have truly pushed the idi platform to new levels! I look forward to seeing what the 9/16 studs do. That should allow for some nice holding strength.

 

Ok Stock 7.3 Head bolt detail... And actually surprising.... To me anyway...

6.425" @0ft/lbs
6.441" @65ft/lbs
6.446" @85ft/lbs
6.448" @105ft/lbs
6.451" @110ft/lbs..... Spec
6.453" @120ft/lbs
Check- .005" stretch- 6.430" @0ft/lbs
6.453" @120ft/lbs
6.460" @130ft/lbs
6.465" @140ft/lbs
Check- .020" stretch- 6.445" @0ft/lbs
6.470" @140ft/lbs..... .005" stretch from last 140ft/lb measurement...

150ft/lbs clicked after 1 full turn...

Broke the bolt at 160ft/lbs....

Bottom line, I wouldn't trust the 7.3 bolts past spec, its just too unpredictable, even if I tested a weak bolt. Based off of this bolt, the stock bolts are pretty much TTY units, even if they aren't officially that way from the factory....

I will probably test another one just verify the results, but im pretty sure this is the way it is....

9/16" stud next...

 

Damn... the 7/16 bolts are as tough as the 1/2"... imagine that.

So based on all of this, where would you say is the boost limit on a stock 7.3 before gaskets are compromised?

 

This really makes me think I want to go with the 9/16" studs if they show better than the 1/2". What would have to be done to make this work on a 7.3 in your opinion? Would the 7.3 have to be drilled at 6.9 depth? And with that depth do you think that there would be issues with thread interference or anything?

 

Jerad, I don't know... lol.

 

I figured you might have tested a lil bit. Sorry about all the questions. I guess that will have to be something for me to look into when the time comes.

 

So 110 is stock torque spec on the head bolt? aka if you wanna run more boost head studs are required? (15-20 psi on stock compression)

 

Stock bolt spec is 110, and I tested it farther, and it hit yield right where the 6.9 bolt did. I expected more out of the bolt, so I don't know, either way, I wouldn't go past 120 on the bolt.

 

Humm.... I thought that 7.3NA was 100 spec and 7.3 turbo was 110 spec and the bolts are the same. Just added torque for the turbo pressure.... I went to 115 on my stock bolts. I think I'm good at that... for 18psi into a decompressed J2 cam Engine at 90cc's .... My next build will get studs for sure...

 

got some studs in, I will be going to 155 foot pounds

 

Before doing the torque test, mark a straight line down the length of the bolt/stud and see what the twist deformation is.

 

Hi,
I'm new please forgive!
First diesel, second post on site.

I'm new to diesels and been reading a lot of info from this site. THANK YOU!
I need to replace the coolant and I believe the head gasket might be leaking.
Obviously from the above posts, ARP are the best. Where do I get these from and what size? I have not taken anything apart yet.
What head gaskets do you recommend? And where to buy?
I got the thermostat information from the "6.9l diesel tech info page" but I guess I missed the gasket and head bolts info.
Additionally any info regarding doing this job will be much appreciated.
Thank you!!

 

Go to ebay for your parts. The stock head gaskets are fine. Confirm that the heads are not warped. If you don't have a good straight edge, Bring the heads to a good diesel machine shop to have them tested.

 

Should i assume you have a turbo? In that case check for wear on the block / heads from the fire rings in the gaskets. If its severe it will lead to more gasket problems. Studs from R&D IDI Performance - Home