Head studs ...?

[93blklightning]

Ok here's my issue. I'm trying to put together a stud kit., without paying the $450.00+ premium for the ARP kit. My question is will Grade 8 work? Or do I need a better material? And does anyone know the exact length, thread length on shaft ends, diameter, and thread pitch of the head studs I need ? If I can make this work with Grade 8 studs , I can put together a stud kit for both sides , for less than $50.00.

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[cpdenton]

The highest rating I have found for grade 8 bolts is 150,000 psi tensile strength.(quick google search) The ARP head studs are rated at 190,000 psi tensile strength. I donr think you would be doing anything more than the stock bolts we already have, but I don't know the tensile strength of stock bolts.

 

[Knuckledragger]

I don't know the length exactly, it is around 6.5 inches. The block threads are 1/2-13 and the head threads on ARP are 1/2- 20. I think the 7.3 has two different length studs, anyway. The 6.9 were all the same length. Grade 8 should be fine as long as you are careful about the installation, lubing the threads, multiple torque sets, etc. The strength of the studs are not as important as the equality of the holding power each one has. The one weak link....

 

[93blklightning]

I don't know the length exactly, it is around 6.5 inches. The block threads are 1/2-13 and the head threads on ARP are 1/2- 20. i think the 7.3 has two different length studs, anyway. The 6.9 were all the same length. Grade 8 should be fine as long as you are careful about the installation, lubing the threads, multiple torque sets, etc. The strength of teh studs are not as important as the equality of the holding power each one has. The one weak link....

Thanks man , I think I'm gonna try it

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[TahoeTom]

http://idiperformance.com/
This guy has a pretty good price on head studs for 7.3 idi. They still aren't exactly cheap. This business is a side job for him, so it may take awhile. YMMV.

 

[93blklightning]

Ok I checked R&D's site, he sells the ARP 8740 chromemoly head studs. According to his site , the studs have a tensile strength of 190,000 psi. The grade 8 studs ....from what cpdenton said above , grade 8 has an average strength of 150,000 psi. Of coarse i don't know if this is for a 1/2" bolt like what's in it or not. Would 40,000 psi make that much of a difference?

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[icanfixall]

Sorry to rain on your parade but grade 8 studs are less than a stock new head bolt. Yeasr ago I bought 2 new head bolts from Ford. I had the company named Stoke test the bolts to fail. They broke at 153,000 lbs. We all know that the stock head bolts in the 7.3 are marginasl at best. Even more so the 6.9 head bolts are way too weak. So studs are a firm recommendation in any 6.9. they are a 7/16 material size. In the 7.3 they are a 1/2 inch diameter size. Each engine has the same length bolts or studs. Theres a lot more to cutting all thread into a stud for either engine. You need to machine off about 1/4 inch of the threads on the bottom so they will not get thread bound. The bare end needs to be tapered to fit into the drilled base at the bottom of the threaded hole in the block. The block has no threads down the first 1 inch. Then it has 1 1/2 inch of thread in the block of 1/2x13 threads. The top threads are 1/2x20 threads. The washers are hardened and ground flat. You can use either 6 or 12 point nuts. they both hold the same amount. ARP sells a designed 7.3 head stud kit and they sell a bulk 7 inch stud that works fie. Many of us have the bulk 7 inch studs in our engines because when we wanted a kit they did not have one. So Russ aka typ4 figured it out that the 7 inch stud works. Also the ARP studs all have a allen hex formed in the top of the stud for ease on installation or removel

 

[93blklightning]

Well hell , I guess there's no way around it. R&D has a better price than everyone else , so I guess. I'll go with him

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[laserjock]

Question for you Gary, you said the bolts failed at 153,000 lbs. was that psi or literally pounds? Bolts and the like are typically done in psi so if you have a 0.5" fastener that's only ~0.2 square inches so you only get an actual yield value of 20% the rated strength.

I know you know this but some may not. If it was not psi, that's a damn tough bolt.

 

[76ford466]

I also tried to get around the high price tag. Even ordered what i though was the 7 in stud but the company i called sent me and priced me 7/16 studs, and arp does make different grade nuts they sent me the cheaper ones. Needless to say i was unhappy and sent them back. So after repricing the right parts it was not any cheaper to buy the indivdual kit. I found the arp right 6.7 length set from the Little power Shop in PA for $494 including shipping. I know it sucks but how much is a set of head gaskets and all the work if one blows and thats the cheapest it could be what if the coolant messes up the bearings which is likly. I got some just because i only want to do my engine once. Even if it made me out at least another month on getting it done with the funding.

 

[TahoeTom]

http://www.ford-trucks.com/forums/1306098-head-bolt-stud-tech-thread.html
Here is a thread (no pun) started by Justin from R&D over on FTE forum. I guess he is going to source some better studs eventually. Pretty good initial test of stud vs bolt in the 7/16 6.9 size.

 

[vegas39]

Since the OP has the 7.3 with better head bolt design, wouldnt he be just fine going back with head bolts?

 

[icanfixall]

The 7.3 head bolt that I had tested broke at 153,000 psi. It broke right at the end of the thread where the bolt body starts. I had them do a spear test too but have forgotten what the bolt speared at. My 89 7.3 ran for many years with my turbo boosting to 13 lbs hauling heavy many hundred thousands of miles. I never lifted a head either. In fact the passenger side head never came off time I pulled that engine to install another built engine. Now thats a great show of the head bolt strength and the gaskets from 1989. Increasing the bolt strength 40,000 lbs is a good idea. Its the added insurance we can keep the heads on the engines when we boost high numbers.

 

[93blklightning]

As you probably know, my intentions are to fab up a '95 PSD GTP38 turbo onto my 93 7.3. These turbos are notoriously **** weak as far as boost goes. Which is good for my sake. But I was talking to a buddy of mine the other day , he suggested I stud it anyway. I'm still debating if its absolutely necessary. Seeing how the stock GTP38 only puts out a max pressure of 17-18 lbs, and that's with the PSD , under a heavy load , and with a lot more fuel than the idi is capable of pushing . Typically pushing 3-5 lbs at cruise . He said that the exhaust outlets are massive com paired to the 95 PSD and the idi may in fact double my boost . I think I may chance it. Worst could happen is pop a head gasket . So long as I run a good boost gauge and keep an eye on it before turning the fuel up , I'm thinking I'll be ok

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[79jasper]

Uh... No. You will not double the boost with a psd turbo. Lol
17-18 is about right for a OBS with the inky dinky injectors.
The SD turbo has a smaller exhaust housing. Or you can get a quick spool housing. Also can get a better compressor wheel.
The 94-97 were 90cc injectors.


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