Head Studs or Bolts?

[Tom68]

Does the coolant seal? Does the oil seal? Does the cylinder seal?

If yes to all those, then you’re probably wasting your time worrying about it.

I am trying to prevent all of those things as I build the engine.....which is why I asked the question. The engine is not yet built. So I don't know if will seal coolant, seal oil and cylinder seal. I would prefer taking the measture in advance that prevent all of that, and not interested in tearing the engine apart AFTER its in the car to try to fix these problems. So.....anyways I am "worrying"about the proper way to build the engine, and asking people here.

On other forums, people have stated that studs provide less distortion in the cylinder walls because the only loads on the stud threads are clamping, without any twisting loads.....whereas a bolt is clamps AND twisting. That seems to make sense, and why I am asking the question. BUT.....that doesn't mean these other guys are right about it.

I guess I will just roll some dice.

Studs installed correctly may be a little better.

[fordified]

Does the coolant seal? Does the oil seal? Does the cylinder seal?

If yes to all those, then you’re probably wasting your time worrying about it.

I am trying to prevent all of those things as I build the engine.....which is why I asked the question. The engine is not yet built. So I don't know if will seal coolant, seal oil and cylinder seal. I would prefer taking the measture in advance that prevent all of that, and not interested in tearing the engine apart AFTER its in the car to try to fix these problems. So.....anyways I am "worrying"about the proper way to build the engine, and asking people here.

On other forums, people have stated that studs provide less distortion in the cylinder walls because the only loads on the stud threads are clamping, without any twisting loads.....whereas a bolt is clamps AND twisting. That seems to make sense, and why I am asking the question. BUT.....that doesn't mean these other guys are right about it.

I guess I will just roll some dice.

NHRA super stock guys ran bolts for decades without a problem. I prefer studs because I don’t like cross treading and helicoiling, but there’s nothing wrong with bolts for what you’re doing.

Torque plate honing is a must for any performance engine. Does it mimic cylinder distortion perfectly. No. But if the rings seal and your leakdown is good then that’s that.

Shadowing at the bolt holes is not uncommon. If the heads still torques and you’re not getting leaks it’s unlikely you’ll get them later.

I surfaced a NASCAR block yesterday and I had to take another thousands of the get rid of the shadows on the water jacket holes. The engine sealed just fine before taking it apart.

I appreciate trying to avoid problems before they start but this is not something I would worry about. Deck the block, put in studs, hone with a torque plate, use good gaskets and move on.

[PackardV8]

One problem with studs not yet mentioned is it's much more difficult to use them with a torque plate. If one is trying to get the theoretically most accurate reproduction of what the cylinder will experience when running, the torque plate needs to be torqued through the studs. Naturally, they're too long and thus will require fabricating spacers/towers to match the head height. I've been there, done that and wish I'd done one cylinder with the short bolts normally used with the torque plate and the one on the other end with the studs and spacers; install the head and from the bottom measure both with the Sunnen dial bore gauge and see if any difference can be found.

[turbo camino]

There is just not much meat around the bolt holes in a 4.125+ bore SBC.

[bentvalves]

total conform.jpg

call total seal and ask about their total conform piston ring.

[modok]

On other forums, people have stated that studs provide less distortion in the cylinder walls because the only loads on the stud threads are clamping, without any twisting loads.....whereas a bolt is clamps AND twisting. That seems to make sense, and why I am asking the question. BUT.....that doesn't mean these other guys are right about it.

That's a load of crap, mostly. I don't want to be rude I'm just being honest about how I feel.... hearing that.
If you think it makes sense then maybe explain it to me? If you hold the bolt stationary and rotate the block is that different? LOL
There probably is some kind of difference in residual twist load but the difference would be the finer thread, which a stud might have, but might not.
Maybe they think finer thread is better or something, or, I don't know what. Not to mention the head gasket, and bolt alignment. Studs will handle a bit more misalignment.
Learn about lubrication and clamp loads stretch and thread loading.
There are charts and such, to determine what torque results in what clamp load.

A stud will wear the block threads less since it does not rotate, so, maybe that's good for long term use, but on the first time use it might just be delaying a small amount of distortion for later. The thread fit and clamp load and stretch are just far bigger factors to be concerned with than what part is rotating.

The first several threads try to hold the bulk of the load in any case, so having more threads engaged does not change anything right away, the extra length is mostly doing nothing, but in the long term it often does pay off, as IMo history shows.
I could go on but I'm mostly answering the questions I assume you might have. Arguing with myself perhaps. lol

[digger]

On other forums, people have stated that studs provide less distortion in the cylinder walls because the only loads on the stud threads are clamping, without any twisting loads.....whereas a bolt is clamps AND twisting. That seems to make sense, and why I am asking the question. BUT.....that doesn't mean these other guys are right about it.

That's a load of crap, mostly. I don't want to be rude I'm just being honest about how I feel.... hearing that.
If you think it makes sense then maybe explain it to me? If you hold the bolt stationary and rotate the block is that different? LOL
There probably is some kind of difference in residual twist load but the difference would be the finer thread, which a stud might have, but might not.
Maybe they think finer thread is better or something, or, I don't know what. Not to mention the head gasket, and bolt alignment. Studs will handle a bit more misalignment.
Learn about lubrication and clamp loads stretch and thread loading.
There are charts and such, to determine what torque results in what clamp load.

A stud will wear the block threads less since it does not rotate, so, maybe that's good for long term use, but on the first time use it might just be delaying a small amount of distortion for later. The thread fit and clamp load and stretch are just far bigger factors to be concerned with than what part is rotating.

The first several threads try to hold the bulk of the load in any case, so having more threads engaged does not change anything right away, the extra length is mostly doing nothing, but in the long term it often does pay off, as IMo history shows.
I could go on but I'm mostly answering the questions I assume you might have. Arguing with myself perhaps. lol

i think what he is saying is that the with a stud the threads that go into the block are not moving relative to the block as you tighten so there is less torsion going into the block and its purely pulling up.

[modok]

Yeah, probably, So it would wear the threads on the block less. Which like I said has pros and cons.
Keep in mind with conrods the bolt VS screw battle is still not settled, and opposite. LOL
At the end of the day IMO, the popularity of studs is because..... cheaper to make a high quality stud than a high quality bolt, you don't have to forge the head. And that's fine. But if a given stud is actually better than a given bolt, that depends.

[turbo camino]

pull.png

[allencr267]

pull.png

Is this an endorsement of stud over bolt, or a tip/warning not to have the threads flush/start at the deck but to be relieved, either a chamfer/countersink or counter-bore down 2 or 3 threads, or something else, whatever?
//
Stock/OEM bolts are fine. Gonna tighten it down 20% or more then stock & need something stronger? They could use a good washer & deck thread prep to spread the load for any non-problems the aftermarket is supposed to solve.
Thanks.

[turbo camino]

It's an illustration of the inherent flaw in the SBC. The part that gets pushed outward is the cylinder wall surface. Compare that to what the same distortion would do to an LS block. The bolt holes are nowhere near the cylinder wall so for the most part it does not affect anything at all. LS also has no threads at the top of the holes, so the stresses are taken way down deep in the block where there's more meat.

[Tom68]

It's an illustration of the inherent flaw in the SBC. The part that gets pushed outward is the cylinder wall surface. Compare that to what the same distortion would do to an LS block. The bolt holes are nowhere near the cylinder wall so for the most part it does not affect anything at all. LS also has no threads at the top of the holes, so the stresses are taken way down deep in the block where there's more meat.

Deeper down has more meat because they put more meat there.
Deeper down stops the deck surface bulging upwards.
Deeper down means if it did bulge the cylinder wall it wouldn't be in the critical area where pressures are highest.

[turbo camino]

LSdeck.png

[barnym17]

If you use a plate and the fastener type you are using at final assembly honestly that's about as good as it gets.Esp with a new unseasoned block Grumpy used to pull his engines back down after a few dyno runs rehone new rings and would pick a FEW ponies per his sbc book.

[Kevin Johnson]

Any builders want to comment on the old idea of putting a BB (round pellet) at the bottom of a tapped hole so that installed studs don't bottom out? Never done it but I recall it being mentioned.