High strength head bolts

Josh Oldenburg

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AS the title says I have searched and found 180k tensile strength bolts that are rated the same as the arp chromoly head studs.If i had the 5-600 dollars id buy the studs.But i dont and i have already sunk alot into this swap to get it ready. The studs measure 6.120 and i can get
1/2"-13 x 6" or 6.25 ASTM A574 Hex Drive Black Oxide Finish Alloy Steel Socket Cap lengths. I dont know if the 1/8 inch longer will effect anything or not. I can get 30 bolts for 150
 

Thewespaul

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Give it a shot and tell us how it works, I would use a thick washer to account for the extra length. Just be weary that if it doesn’t work you’ll be starting over again....
 

icanfixall

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Before you change the lengths please measure the lenght of what is standard. Reason I tell you to do this is ALL the head bolt holes drilled in the block are the blind hole type. None of them enter any water passages like many gas engines do. Buying one new bolt and comparing it to the standard bolts is my best advice. Also just to let you know. The threads cut into the block are well below the head surface by around 5/8 or 3/4 inch down. Reason for this is you wont be pulling any threads up against the head creating a gasket leak.Good luck on this new interesting idea.
 

Josh Oldenburg

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So i should be concerned about how much is threaded? I'm not sure on the overall length of a factory bolt yet, just know the arp stud length
 

Macrobb

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A couple of useful links:
https://www.ford-trucks.com/forums/1306098-head-bolt-stud-tech-thread.html#post14206820 - Looks like we can use 9/16 if needed(but only to 6.9 depth) and
https://www.fastenal.com/products/details/23905 - 9/16-18 5.5"(bottom of cap down I believe) Looks like we can get these cheap.
Or https://www.fastenal.com/products/details/23904 (5" from bottom of cap down).
http://www.dieselwarden.net/ford/project18.html - neat info on bolt lengths

This may be overkill for what you are doing, but if the 1/2" ones don't hold.... this actually looks doable(with proper drill/tap). Sure looks like 5" SHCSs would be perfect. The fine thread might be a little harder to do, but will actually have more strength anyway... not that that will be needed with 9/16 bolts.
 

Fision

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Today I ran across relatively inexpensive “ARP replacement stud kits” on eBay, ~$5-10 each stud depending on the kit and vendor. The kits I saw covered the various Powerstrokes and Cummins, so I sent an inquiry to one vendor about idi spec studs. Waiting to hear back...
I’m sure these are from China or equivalent, but claim to be 8740 alloy/180k with threads rolled after heat treatment.
Anyone know/hear anything about these?
 

Thewespaul

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The only experience I have with the Chinese arp studs are in ls engines. They were pretty popular for a couple years, but a few people stress tested them and found the were weaker than the stock headbolts.
 

Macrobb

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Hm... I'm curious about 9/16 Chinese studs. Even if slightly weaker than stock(PSI), with more meat it might be a valid option.
 

Fision

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The only experience I have with the Chinese arp studs are in ls engines. They were pretty popular for a couple years, but a few people stress tested them and found the were weaker than the stock headbolts.
WHAT!!! They LIED?!?:Banned
Figures. If it sounds too good to be true,—sign me up!
Well almost... I keep hoping and trying.
Before I completely close the book on this, you mention they were weaker than the stock head bolts— by how much? My understanding (in much need of *********** and refinement) is that studs are superior even if of identical strength to bolts because of the finer threads on the torqued end?
If these cheapo’s are consistently of comparable strength then wouldn’t they still be a step up from bolts?

You also mentioned they were popular for a few years— were there any Chinese stud related engine failures that you’ve heard of? I’m particularly interested in the answer to this as it would provide a body of evidence as to the real world advisability of these.
 

Thewespaul

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The Chinese studs are weaker than the stock head bolts, meaning they couldn’t perform as much clamping force as a stock head bolt. Usually the threads would strip when torqueing them down or they would break when the engine is under a load causing a blown head gasket.

As for running a 9/16 Chinese stud, then you have the cost and hassle of machining the block to accept the 9/16 stud. If this is done incorrectly, your block is a boat anchor.

Imo, there’s nothing wrong with arp studs for the 7.3s, great product at a reasonable price with no failures to speak of.
 

Fision

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The Chinese studs are weaker than the stock head bolts, meaning they couldn’t perform as much clamping force as a stock head bolt. Usually the threads would strip when torqueing them down or they would break when the engine is under a load causing a blown head gasket.

Stripped threads, blown gaskets—Those are the specifics that sell me on your advice.
The price tag on my rebuild keeps going up o_O
I should stop asking questions— every time I do my wallet gets thinner—but... at what point (hp/torque/boost/???) are studs recommended for the crank mains? Should the original Main bolts always be replaced in a rebuild or are they usually ok to reuse?
 

genscripter

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AS the title says I have searched and found 180k tensile strength bolts that are rated the same as the arp chromoly head studs.If i had the 5-600 dollars id buy the studs.But i dont and i have already sunk alot into this swap to get it ready. The studs measure 6.120 and i can get
1/2"-13 x 6" or 6.25 ASTM A574 Hex Drive Black Oxide Finish Alloy Steel Socket Cap lengths. I dont know if the 1/8 inch longer will effect anything or not. I can get 30 bolts for 150


Not worth the risk for the minuscule cost savings.
 

IDIBRONCO

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were there any Chinese stud related engine failures that you’ve heard of?
They were in LS engines. In my opinion, THAT'S a BIG failure right there!
Should the original Main bolts always be replaced in a rebuild or are they usually ok to reuse?
The main bolts are fine to reuse and I've never heard of anyone saying otherwise. Maybe if you're trying for absolutely huge power numbers, then you should use main studs. The lower end of our engines are really heavily built and will hold up to WAAAAY more power than these engines made stock.
 
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