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Advantages of head studs

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Old 04-05-2004, 12:16 PM
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Default Advantages of head studs

What are the advantage of head studs? I can see that if the motor is taken apart often, this would move the wear from the block threads to the stud threads, but was wondering if there were other advantages?
Old 04-05-2004, 12:21 PM
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Don't do it they are a PITA! Take it from me just do ARP head bolts. Way easier to take it apart again if necessary and they are reusable as many times as needed. I also used Cometic gaskets which I reused several times with no issues

Chris
Old 04-05-2004, 01:20 PM
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I personally like head studs, yes they are a little more of a PITA, but they have far superior clamping force compared to bolts.
Old 04-05-2004, 01:22 PM
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Why (or how) do they provide superior clamping force?
Old 04-05-2004, 01:29 PM
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I just pulled my heads off with the head studs, let me tell yah after doing almost 10 h/c swaps and removing stock bolts, this was a piece of cake. It took me almost an hour less taking the heads off then it would have with the stock bolts, i think its from the stuff they use on the bolts(loctite i guess) that makes it take soo long to get them out.
Old 04-05-2004, 03:01 PM
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Originally Posted by 98_1LE
Why (or how) do they provide superior clamping force?
The stock bolts are torque to yeild. The studs don't stretch.

Also, in an aluminum block with aluminum threads, the chances of galling a thread are high, the more times you R&R heads. Rule of thumb is no more than 4 times, so I've heard ...
Old 04-05-2004, 04:05 PM
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Originally Posted by 98_1LE
Why (or how) do they provide superior clamping force?
My understanding is that decent studs have rolled threads on the nut end. This means that there is less friction between the nut and stud so when you torque to the recommended setting (to stretch the stud) you will have a lot of extra clamping. The other thing which comes to mind is that the load is nearly all applied to the nut end of the stud as opposed to the threaded end in the block.

I read somewhere that engineers use studs and accountants choose bolts.
Old 04-05-2004, 04:08 PM
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when I had my motor built up I just went w/ARP Head bolts... I thought about studding but I'm not going to be pulling my heads (hopefully) often enough to really need them... plus I've heard you can't get the heads off (or at least passenger side) w/the motor in the car w/studs? Is this true?
Old 04-05-2004, 04:11 PM
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Clamping force is way better and no stretch and I didn't think they were tough to do at all.
Old 04-06-2004, 12:20 AM
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I put head studs on my 99'....I took the heads off so MTI could polish them up, put on dual springs, and 2.05/1.60 valves.....took me at least an hour less to pull my heads....I love'em.
Old 04-06-2004, 09:31 AM
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both heads will come off w/ the motor in the car w/ head studs. stop spreading that rumor. i've done it myself. the friction is not being applied to the aluminum threads, just a pulling force. its the friction of getting tight and the pulling that will cause the threads to gall.
Old 04-06-2004, 11:58 AM
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Originally Posted by mitchntx
The stock bolts are torque to yeild. The studs don't stretch.
If they dont stretch, they wont clamp. Did you study Youngs modulus in high school? ...I would bet the ARP studs are made from exactly the same material as the bolts.

The only benefit I can see is for multiple head swaps. You can lock the studs into the aluminum block with Loctite (much better to have a bonded threaded assembly). Then when you torque/loosen/retorque ...all of this is done between the stud and nut which are both high tensile steel.

...probably also gives a better torque/tension relationship which will result in more consistant clamp loads across the head.

Ps. I am a Loctite Engineer so nuts and bolts are my bread and butter!
Old 04-06-2004, 01:54 PM
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Thanks everyone. I asked my father as well, who is also an engineer, and he agrees that they will not "clamp" any better, or resist stretching unless they are a larger diameter material. Still, to save the wear on the block I think I will order a set.
Old 04-06-2004, 02:18 PM
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Let us not forget the cleaning factor. With head studs, you do not have to clean out the bolt holes ever again, since they just stay in the block.
Old 04-06-2004, 02:21 PM
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Why studs offer more clamping force as opposed to bolts:

Studs also provide more accurate and consistent torque loading. Here’s why. When you use bolts to secure the head, the fastener is actually being “twisted” while it’s being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. A stud should be installed in a “relaxed” mode—never crank it in tightly using a jammed nut.

If everything is right, the stud should be installed finger tight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. Remember, an undercut shorter stud will have a rate similar to a longer, standard shank stud. This provides a more even clamping force on the head. Because the head gasket will compress upon initial torquing, make sure studs and bolts are re-torqued after the engine has been run
Old 04-06-2004, 02:55 PM
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ive seen some serious small blocks built with arp head bolts. id say they arent worth the money if your not rebuilding the thing all the time or looking to make maximum maximum power. arp head bolts and bolts in general are extrememly strong. im just going with bolts myself. ive also heard you cant take the heads off with studs if the motors in the car. i was tol dthat from my man at ramchargers. ive never tried it though, but it definetely seems like it would be a tight fit...
Old 04-06-2004, 05:48 PM
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removeing the heads on some cars w/ head studds cannot be done, but i have done this on my own car (98 Z) so it can be done. i had ZERO issues w/ doing this.
Old 04-06-2004, 05:56 PM
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Stay with the stock bolts below, say, 500 hp. I use 9/16" studs, but I can make over 900 rwhp and have had problem lifting heads.
Old 04-06-2004, 06:05 PM
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Short Laymans version: A bolt with be both "stretched" and "twisted" while torqued. A stud will only be "stretched".

This twisting force has to be added into the total force applied to the fastener.

I use red loctite on head studs and install them finger tight. Smokey Yunick and Carrol Smith do (did) as well.
Old 04-06-2004, 09:03 PM
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If the clamping force is no better, why would an NHRA or NASCAR engine, which is rebuilt every pass/race, use studs? Studs are superior.


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