Head studs?
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Fleet Owner
Joined: Jan 2004
Posts: 26,007
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From: Brentwood,CA
Head studs?
Okay this https://www.ford-trucks.com/forums/1...ds-anyone.html most of us here know about head studs and have used them plenty of times. I have never heard of a need for machining the deck to compensate for studs or that studs transfer the load different? I just figured someone here would know the true answer to the studs. I know its not IDI related but you are the best people for the job
Postmaster
Joined: Dec 2004
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From: Maple Valley, WA
Okay this https://www.ford-trucks.com/forums/1...ds-anyone.html most of us here know about head studs and have used them plenty of times. I have never heard of a need for machining the deck to compensate for studs or that studs transfer the load different? I just figured someone here would know the true answer to the studs. I know its not IDI related but you are the best people for the job
Postmaster
Joined: Dec 2004
Posts: 2,941
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From: Maple Valley, WA
Your right about torque being torque, but where you wrong is about thread pitch... And thats the difference between studs and the factory bolts. The bolts are a Course thread, and clamping load with a course thread is less than clamping load with a fine thread. There is a huge difference between 90 ft/lbs with headbolts, and 90 ft/lbs with head studs... Like 40% more clamping load...
Postmaster
Joined: Dec 2004
Posts: 2,941
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From: Maple Valley, WA
Its best to torque plate hone your engine with your studs set at the torque your going to have your heads to. That way your bores will be perfectly round when your engine is running.
My studs are torqued to 150 ft/lbs and while not ideal on the factory setup (bore deflection issues) mine is holding up fine. Id rather have my gaskets hold and have a little blowby, than be chancing the HG's blowing everytime I boost...
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From: Des Moines
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Posting Guru
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From: Princeton MN
That is something I have never heard of before. Sure stock bolts are corse thread, but as ARP states that sometimes up to 60% of the final torque is just to overcome the friction of the threads, combinre that with the twist in the bolt you are getting real poor clamping force with bolts.
I think the bore deflection is bull. I could see how it would make sence if all studs were running in different directions, but they pull strait up, what could possibly deflect? And with the studs you get a more even torque over the whole surface of the head, so every bolt is pulled the same and has an even TRUE torque over every stud, unlike the incosistant torque of bolts which should cause more deflection due to the incosistancy.
I think the bore deflection is bull. I could see how it would make sence if all studs were running in different directions, but they pull strait up, what could possibly deflect? And with the studs you get a more even torque over the whole surface of the head, so every bolt is pulled the same and has an even TRUE torque over every stud, unlike the incosistant torque of bolts which should cause more deflection due to the incosistancy.
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Postmaster
Joined: Dec 2004
Posts: 2,941
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From: Maple Valley, WA
The reason for the bore deflection, even beyond the idea that the studs/bolts pull "straight" is that the casting is un-uneven throughout the block. Pulling straight on something doesnt necessarily mean that the forces being spread throughout the casting are linear. You would be right if the block was a solid piece of cast or billet... But its not. The bores are the biggest unsupported part in the block and therefore the most likely spot to deflect under load.
The real question is, how much... And what is too much... Like I said, Im at 150ft/lbs and so far Im fine. Next IDI I build will be torque plate honed, this one wasnt an option.
The real question is, how much... And what is too much... Like I said, Im at 150ft/lbs and so far Im fine. Next IDI I build will be torque plate honed, this one wasnt an option.
Tuned
Joined: Oct 2006
Posts: 375
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From: Beaumont Tx
Been doing this for twenty years now and several of them in a machine shop and never heard that one before. More than likely some engineer decided he needed to make more money and came up with the idea.
Posting Guru
Joined: Jan 2010
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From: Terre Haute, IN
I dont know if this is the truth, but i thought it interesting...
CYLINDER DISTORTION AND DECK PLATE HONING ON CUMMINS 5.9 - YouTube
CYLINDER DISTORTION AND DECK PLATE HONING ON CUMMINS 5.9 - YouTube
