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Mains studs

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Mains studs
#1
  This topic is about my 1969 MG MGC GT
JMA Avatar
JMA Silver Member John Anderson
Donvale, Victoria, Australia   AUS
Probably a little early in the build process, as I'm still stripping the engine down.

But has anyone used mains studs rather than the usual bolts on these engines?

I know that the front cap is quite close to the bottom and leading edge of the sump but I figure a 3.75" stud will clear and leave enough thread for the nut and washer.



Edited 1 time(s). Last edit at 2019-03-03 11:21 PM by JMA.

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kirks-auto Platinum Member Robert Kirk
Davenport, IA, USA   USA
Those are very special bolts and their use is rare. I've keep them in stock and you can read more about them on my web site. Use of a nut implies use of a locker and that is a lot of potential loose hardware ratting around where you don't want any hardware to come loose. I would NOT use studs and nuts on the main caps.



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Ken Plumstead Avatar
Smithers, BC, Canada   CAN
1965 MG MGB
1968 MG MGC GT
Sorry Robert but I’ll have to jump in here with a small correction.

The MGC main cap bolts are the same as the MGB 18V main cap bolts. 12B2356. Not so special or rare. One can get them from the usual suspects or really good ones from ARP.

Also, lock washers are not normally used in a high torque applications, just hardened flat washers. The lock washers don’t 'dig' into the block or the hard nuts and any ’spring’ they possess is completely overpowered by the high torque.

As a footnote: I did a bunch of reading about fasteners including the NASA fasteners study and what I learned was, split lock washers are just about the most useless thing ever invented. Their touted benefits are just myths. They don’t do anything. I am not using any on my rebuild, opting for Nylocs in most places instead.

Ken



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Ken Plumstead Avatar
Smithers, BC, Canada   CAN
1965 MG MGB
1968 MG MGC GT
In reply to # 3902205 by JMA
But has anyone used mains studs rather than the usual bolts on these engines?

Hi John,

You probably could, clearance permitting, but I'm thinking that ARP bolts would be the way to go. I've noticed on the 'Motorsports' forum that the MGB racing crowd seems to like using 18V blocks in their race engines so they can bolt their main caps on instead of using studs. It might just be follow the leader or they might actually be on to something. Hap would be a good person to ask about this.

Ken



MG: Transforming gasoline into Fun!!!

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JMA Avatar
JMA Silver Member John Anderson
Donvale, Victoria, Australia   AUS
I'm firmly in the stud preference camp, I understand many people like bolts but I prefer the 'feel' when tensioning stud and nut. I have frequently replaced bolts both heads and mains with studs, but I wouldn't rule out still using bolts but it won't be these 50 year old ones. I have new head studs and will also replace the rod bolts and resize them as a matter of course.

I don't have any contact inside ARP but have used their fasteners for many years without fault, I emailed them and still waiting on a reply.

Personally I'm not a fan of Nyloc's in engines but I won't be critical either, I take the view of 'each to their own'.

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Ken Plumstead Avatar
Smithers, BC, Canada   CAN
1965 MG MGB
1968 MG MGC GT
I am in the ARP preference camp whether it be studs or bolts. This is the first time I have used bolts for main caps and I did notice the different feel when tightening them up. I guess that's the difference between 'clamping' and 'squeezing'. Unfortunately ARP doesn't have anything for us to replace our head studs. It's because the head studs are fine thread on both ends. Argh!!!

I'm big on new fasteners too. I'm replacing just about every fastener on my car. I've got a box of original fasteners that I'm sure some of the concours people would love to get their hands on.

I agree on not using Nylocs for hot applications of course. They are working great on the suspension bolts though.

Ken



MG: Transforming gasoline into Fun!!!



Edited 1 time(s). Last edit at 2019-03-04 03:51 PM by Ken Plumstead.

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JMA Avatar
JMA Silver Member John Anderson
Donvale, Victoria, Australia   AUS
Ken,

We're singing from the same song sheet my friendsmileys with beer

I got my hands on a set of ARP head studs from Doug Smith in the UK, although they came in a Kent Cams box they are most definitely ARP.

As far as Hap is concerned he's always welcome to add something but he strikes me that he will only do so if he has something to say.

The point of the thread was to ask if anyone has actually fitted studs to this engine and if so what the correct length stud was used.

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twentyover Avatar
twentyover Greg Fast
Lives in SoCal, Resides in the Burbs of Detroit MI, USA   USA
In reply to # 3902625 by Ken Plumstead .... Unfortunately ARP doesn't have anything for us to replace our head studs. It's because the head studs are fine thread on both ends. Argh!!! ....

B series stud sets have bespoke Fine/Fine studs. Because of the crappy replacement studs available today and the volume of B series head being rebuilt, the fact that so many MGB's are and were raced, ARP can justify a bespoke build based on the number of studs that are consumed, they have made Fine/Fine to match the production style.

Most US stud sets are fine on the open end, coarse on the end that screws into the base.

Playing devils advocate, WHY do MGC head studs need to be Fine/Fine? No reason I can see except to match what the factory did. Why not drill the fine end into the block, and run a coarse nut on top the head to screw it down? Now I realize that the lengths of coarse and fine pitch segments are different. Does that make the idea unusable? You my not be able to bottom the block side stud thread, is this a problem? I don't know, I think i need to think about how long ARP studs are, and the length intervals they produce. I do know they produce coarse thread nuts.

I'm not sure I believe that an MGC needs an aftermarket head stud, but this may be a way to get an ARP stud if you don't mind thinking a little differently than Saint Abingdon

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kirks-auto Platinum Member Robert Kirk
Davenport, IA, USA   USA
Place bolts such as used on main caps and USA flywheels are rather unique in design, I did not mean to suggest rarity. By design they do not require an additional locking device and that was my point.



Regards,
Robert Kirk

kirkbrit@yahoo.com
E-mail PLEASE for quote/questions/orders

Business phone 563 323 1017

http://kirks-auto.com/
Moss distributor/UK importer
Beat or match most retail/delivered quote


Member Services:
Parts for your classic British and Italian car. 30 years in business.
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Ken Plumstead Avatar
Smithers, BC, Canada   CAN
1965 MG MGB
1968 MG MGC GT
I'm pretty sure that B series head studs are fine/coarse thread. I'd have to go downstairs and dig out my old head studs to verify that though.

I called ARP when I was looking for new head studs and they said they did not make a dedicated MGC head stud and they didn't make 'any' fine/fine thread studs. Like you said, if you came up with a big enough demand, I'm sure they would. In the end I had to go with the Moss set.

In regards to your upside down fine/coarse stud idea; the fine thread upper end has the longer threaded section, so if you put it in upside down in the block the short coarse end threading would probably not go all the way down to the top of the head leaving the nut hanging out there in space.

Now, the redneck solution to that would be to throw a die on it and cut some more coarse threading on the stud so that the nut would run all the way down to the block but I'm thinking that might not be a good idea on a hardened head stud.

Ken



MG: Transforming gasoline into Fun!!!

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pfg49 Gold Member Peter Gascoigne
Southampton, UK   GBR
Socket headed screw with correct tensile strength and a suitable load spreader?

I thought the original question was about mains bolt, where did we jump to head studs?



Edited 1 time(s). Last edit at 2019-03-05 10:08 AM by pfg49.


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twentyover Avatar
twentyover Greg Fast
Lives in SoCal, Resides in the Burbs of Detroit MI, USA   USA
In reply to # 3902653 by Ken Plumstead .....

Now, the redneck solution to that would be to throw a die on it and cut some more coarse threading on the stud so that the nut would run all the way down to the block but I'm thinking that might not be a good idea on a hardened head stud.

Ken

The correct way to do it would be to make sure the threads were clean- drill the fine section into the block deep enough to account for gasket thickness, head thickness, nut thickness, and probably two washers.

making sure the threads don't hang up and drill the stud deeper in the block, make sure that the single washer you use has 1 - 1.5 full threads covered because the stud will stretch.

OK, the stud is bottomed in the block and still too long? there should be a number full threads proud of the block if the stud is bottomed. Grind down the end of the stud until only 1 or two of the threads is proud of the block. Still too long? Look to the FAA, you can stack hardened washers to get the threads height correct.

Now that i think about it, What I just described does sound a little redneck

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Ken Plumstead Avatar
Smithers, BC, Canada   CAN
1965 MG MGB
1968 MG MGC GT
Greg,

I'm thinking you are over thinking this way too much.grinning smiley


In reply to # 3902635 by JMA
The point of the thread was to ask if anyone has actually fitted studs to this engine and if so what the correct length stud was used.

John,

Sorry for the misdirection of your query. Sufficed to say I don't think anyone has tried the stud thing or is at least willing to admit it.

Ken



MG: Transforming gasoline into Fun!!!

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