Head studs are over hyped

T

TheStarletGT

Member +
Head studs are rubbish and over hyped

Head studs are better than bolts, ummm, i dont think so. head studs are a waste of time and is over hyped. Lets look at some facts >

We want to clamp the head down, right, so with bolts, the bolt thread is like what 5-7cms in lenght and is threaded into the head. So how many threads are along 5-7cms of bolt, 40-50?

Head studs: These are screwed into the head, a very easy way to (GUIDE) the head down into position. So what is next, nuts, how thick is the nut, 10mm and how many threads is in a 10mm width of nut, prob 10.

So my question is, how are head studs better. How can nuts screwed on a shaft be better than a long bolt drilled into the head, with like 80 or so threads. Im sure as hell wont use nuts to clamp down a cylinder head. Just think of the stress put on the nuts thread.

Can you just picture the thought of 60 odd newton metres on a nut. This head stud modification is garbage. I rather have 10 bolts with like 60 threads on each bolt to clamp down a head unlike nuts with just 10 or so threads.

10 Bolts: estimate to have 600 threads if each one had 60 threads.
Head studs: a measly 100 threads if each nut had average 10 threads.


Do you get what im trying to point out. All the force when using studs is on the nut. The studs do jack all, only good for guiding.

When using bolts, the whole threaded shaft clamps down the head, so thats mega surface contact. When using head studs, the nut is only grabing 10mm or so of thread stud shaft, so tell me why head studs are better. Whats the point in screwing the studs in the block, just like bolts, and have a nut clamp down the head. Just use bolts.


I have never used them nor will i ever.
 
Last edited:
Franza1

Franza1

Supermoderator & Area Reps Manager
You are not looking at this from an engineering point of view you are looking at this from a not factual logic point of view.

So your whole argument is that you will not have the same amount of threads in contact.. well let me put it to you this way you say there is 600 threads for each bolt and that makes for more force than the 100 threads that are on the stud. well let me put it to you this way the studs are threaded into the block as well as a nut being threaded onto the top of them. so that makes the 600 threads just like the bolt plus the 100 of the nuts.

But the real engineering part of this is simple force.

Bolt

You are threading it into the block and applying load on it. now this load is across two planes vertical and rotational . Vertical being the clamping load that the bolts are applying to the head to keep it secured to the block and the rotational load applied to the bolt in order to tighten it. if you know your physics the rotational load is the one that is the greatest threat to the bolt as the bolt is esentially a cylinder and cylinders are weakest with rotational loads.

Stud

You are threading the stud into the block, the stud does not have to be torqued into the block so the stud it's self does not have this rotational load applied to it, when you tighten the nut onto the top of the bolt you are not applying any rotational load just a vertical load so the stresses on the whole fastening system is not as great as it only has one plane of load to deal with.

there is a whole other reason to use studs rather than bolts which involves torque accuracy but since you are only on about loads and forces i will not go into this.
 
B

bullet

Member +
A+++++ reply!!

Franza1 said:
You are not looking at this from an engineering point of view you are looking at this from a not factual logic point of view.

So your whole argument is that you will not have the same amount of threads in contact.. well let me put it to you this way you say there is 600 threads for each bolt and that makes for more force than the 100 threads that are on the stud. well let me put it to you this way the studs are threaded into the block as well as a nut being threaded onto the top of them. so that makes the 600 threads just like the bolt plus the 100 of the nuts.

But the real engineering part of this is simple force.

Bolt

You are threading it into the block and applying load on it. now this load is across two planes vertical and rotational . Vertical being the clamping load that the bolts are applying to the head to keep it secured to the block and the rotational load applied to the bolt in order to tighten it. if you know your physics the rotational load is the one that is the greatest threat to the bolt as the bolt is esentially a cylinder and cylinders are weakest with rotational loads.

Stud

You are threading the stud into the block, the stud does not have to be torqued into the block so the stud it's self does not have this rotational load applied to it, when you tighten the nut onto the top of the bolt you are not applying any rotational load just a vertical load so the stresses on the whole fastening system is not as great as it only has one plane of load to deal with.

there is a whole other reason to use studs rather than bolts which involves torque accuracy but since you are only on about loads and forces i will not go into this.
Click to expand...
 
davehart

davehart

Member +
Great reply Franza, I think that explians it.

There is also the fact that if they are indeed better, why are they not used in the first place?
 
A

alexroberts

Fresh Recruit
lol, owned. as its a conversion surely its been revised and more than likely made out of a higher grade of steel as well i would assume
 
gv1.3

gv1.3

Admin
HEAD STUDS vs. BOLTS...A TECHNICAL DISCUSSION

ARP's factory Tech Representatives are often asked which is better, cylinder head studs or bolts. The answer, invariably, depends on the installation. On many street-driven vehicles, where master cylinders and other items protrude into the engine compartment, it's probably necessary to use head bolts so that the cylinder heads can be removed with the engine in the car.

For most applications, however, studs are recommended. And for good reason. Using studs will make it much easier to assemble an engine (especially a racing powerplant which must be serviced frequently and quickly!) with the cylinder head and gasket assured of proper alignment. Alamo Motorsports offers the complete line of ARP Head Studs in addition to ARP Head 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.

source
http://www.alamomotorsports.com/arp/arp_headbolts.html
 
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