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Which means "Evil Twin". Lets see your projects where you change boring into fun or create the fun from scratch.
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PostPosted: Wed Apr 15, 2020 8:11 am 
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TheDarkSideOfWill wrote:
14mm head studs? Hello 30 psi!

In my limited metallurgical knowledge, I think GM's problem with the Northstar 11x1.5 threads was stress corrosion cracking.
Not sure if the 14x1.5 thread is enough larger in diameter to reduce the stress enough not to have that problem or if the difference in casting alloy would eliminate it.

Do you know what alloy Ferrari uses?


14 in the block, M11-1 I think it is for the part that goes through the head. The ferrari studs are long and basically pull from the main bearing area not the deck so they need the larger OD to be stiff enough I guess. The only problem I've seen is the head gasket leaks a bit around the studs and the water cause the studs to corrode the aluminum head and block. The threads in the block are deep so they seem fine but the body of the stud become stuck in both the block and head, making removing the head a bugger you need to make a puller to get the head off and trying to remove the studs from the block can destroy the threads. On the 308 and TR heads I opened up the holes a bit to make the binding near impossible and also use a bit of sealant around the suds.

I coould never find out what the block alloy is exactly..."proprietary alloy" is all I found.

....but 30psi is known OK(ish) on ferrari engines ;)


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PostPosted: Wed Apr 15, 2020 9:33 am 
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FoaTech wrote:
I have needed odd quantities of ARP studs for unconventional projects and I just call them and tell them what I want and the send it. I had custom studs made years ago, like 1999. The company is top notch, expensive, but top notch. It is much easier now that the tuner crowd has been blowing up stuff and needed more metric stuff. When I started getting custom studs, they would put standard threads on the nut end because they didn't make metric nuts.
Anyway, just call them, they will work with you.


The 11x1.5 studs I have use 7/16-20 threads at the top end.

I'm not sure what the LS studs use at the top end. I had to call them about flywheel bolts as well. The cast cranks use 8mm flywheel bolts. The forged cranks use 11x1.5 flywheel bolts. Fortunately that's the same as LS engines. The automatic LS flexplate bolts are the right length for me to have my flywheel reworked for that length. If I build another one, I'd use the "adapter" flywheel bolts that are made for a flexplate + the LS to TH400 crank flange adapter.

The LS engines use 6 bolts, the Northstar uses 8. I'll have to ask about those as well.


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PostPosted: Wed Apr 15, 2020 10:01 am 
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mk e wrote:
TheDarkSideOfWill wrote:
14mm head studs? Hello 30 psi!

In my limited metallurgical knowledge, I think GM's problem with the Northstar 11x1.5 threads was stress corrosion cracking.
Not sure if the 14x1.5 thread is enough larger in diameter to reduce the stress enough not to have that problem or if the difference in casting alloy would eliminate it.

Do you know what alloy Ferrari uses?


14 in the block, M11-1 I think it is for the part that goes through the head. The ferrari studs are long and basically pull from the main bearing area not the deck so they need the larger OD to be stiff enough I guess. The only problem I've seen is the head gasket leaks a bit around the studs and the water cause the studs to corrode the aluminum head and block. The threads in the block are deep so they seem fine but the body of the stud become stuck in both the block and head, making removing the head a bugger you need to make a puller to get the head off and trying to remove the studs from the block can destroy the threads. On the 308 and TR heads I opened up the holes a bit to make the binding near impossible and also use a bit of sealant around the suds.

I coould never find out what the block alloy is exactly..."proprietary alloy" is all I found.

....but 30psi is known OK(ish) on ferrari engines ;)


The Northstar head bolt threads are mid-way down the outer walls of the block. I would like them to be way down in the main bulkheads, but they're already pretty good.

Can't you counterbore o-ring grooves around the head bolt holes in your heads or block to seal the water out of those locations?


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PostPosted: Thu Apr 16, 2020 6:50 am 
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I had 275 4 cam block with a head stud broken flush with the surface. I ended up taking it to a tool and die shop and they used an EDM machine and "burned the stud into a thin wall tube and at the very bottom "burned" it into a set screw and an allen wrench took the stud right out. Never touched the block and the threads were not damaged at all. It wasn't cheap but given the block was unobtainium, it was worth it.

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PostPosted: Thu Apr 16, 2020 8:13 am 
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EDM is pretty amazing.

The Dark Side of Will on another forum wrote:
I finally got OnShape customer support to find me a workaround for a bug I found (that they won't admit is a bug) and was able to model this up.
Because the pin block is very hard, milling this won't work, it'll have to be EDM'd.

Image


The Dark Side of Will on another forum wrote:
So the prototype machinist recommended I have this EDM'd because it's hardened.

The machine shop sup at work said he had a cutter that could do it, but he'd just need some time when the boss isn't around, etc.
7 months later it was still on his desk.
So I snagged it and took it to the EDM place.
Two weeks later, tada.
Ooooooh, shiny!
The surface finish in the cut is REALLY good... but that's what EDM does. Per my model, the minimum distance from the notch to the pin bores is only 0.025 or so... pretty good fixturing to cut that without screwing it up.

Image

Image

Image


I had the notch in this round block EDM'd before I decided to try a different technical solution for this project. The wall thickness between the notch and the two nearby pin bores is <0.020 and the EDM didn't break through. Check out the surface finish too.


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PostPosted: Thu Apr 16, 2020 8:16 am 
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FoaTech wrote:
I had 275 4 cam block with a head stud broken flush with the surface. I ended up taking it to a tool and die shop and they used an EDM machine and "burned the stud into a thin wall tube and at the very bottom "burned" it into a set screw and an allen wrench took the stud right out. Never touched the block and the threads were not damaged at all. It wasn't cheap but given the block was unobtainium, it was worth it.


That was outer wall, not the V, and you could access the bottom of the stud?


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PostPosted: Fri Apr 17, 2020 6:32 am 
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That was outer wall, not the V, and you could access the bottom of the stud?[/quote]

I am not sure what you are asking. Help me out here.

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PostPosted: Fri Apr 17, 2020 9:25 am 
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On each bank of a V engine, there's are two rows of head bolts... one "inboard" row close to the V and one "outboard" row in the "outer wall" of the block. I'm also thinking that in order for a wire EDM to be able to cut the stud like that, the bottom of the stud would have to be accessible... IOW the tapped hole in the block is not blind.

I don't know the right term right off, but I know there is a different type of EDM that can cut arbitrary shapes, but needs case-by-case tooling production... That's all I know about that, beyond it being expensive.


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PostPosted: Fri Apr 17, 2020 11:24 am 
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EDM is awesome....my drop gear setup was all wire EDM'd to create splines in the hardened gear and matching hub. Luckily in those days I work someplace where there was after hours access so it only cost beer for the machinist to stay late.


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PostPosted: Mon Apr 20, 2020 6:45 am 
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TheDarkSideOfWill wrote:
On each bank of a V engine, there's are two rows of head bolts... one "inboard" row close to the V and one "outboard" row in the "outer wall" of the block. I'm also thinking that in order for a wire EDM to be able to cut the stud like that, the bottom of the stud would have to be accessible... IOW the tapped hole in the block is not blind.

I don't know the right term right off, but I know there is a different type of EDM that can cut arbitrary shapes, but needs case-by-case tooling production... That's all I know about that, beyond it being expensive.


I see now. This was not wire EDM, it was a sink erosion. They bored it first and then burned in a socket head so an allen wrench was used to unscrew the stud.

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