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MilanoGuy asks some good questions about the studs. Does this company require the studs to be removed to perform their work on the block? I understand they are very hard to remove and sometimes ruin the block in the process.
 

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Any modification that results in a closed deck will require removal of the studs. Even if a stud breaks, there's no reason to scrap the block. EDM (Electrical Discharge Machining) can remove them.
 

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Hi 4sfed

How do you remove the studs from a block? Do you put the whole block in a industrial oven and heat it?

I've never intentionally removed a head stud. I've had a head stud tear out of a bock and I repaired that by having a machine shop install a timesert down in the block.

I see your Avatar is the Boneville speed record car are you affiliated with them?

Bye
 

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Jim was the engine builder and pilot.
 

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Hi 4sfed

How do you remove the studs from a block? Do you put the whole block in a industrial oven and heat it?
I grip the threads at the top of the stud with a collet with matching internal threads, then locally heat the area where the stud screws into the block with an acetylene torch. Aluminum cutting oil is applied where the stud screws into the block. A few sharp blows to the top of the collet tool and the stud comes out or breaks off.

If it breaks, I use a vertical mill to remove the stub. It's not a job that can be reliably done with a pistol drill. Lacking a mill, there are shops with EDM (Electrical Discharge Machining) equipment that can easily remove the stubs.

There is another technique I recently learned about. This method uses a 300 amp welder shorted for 10 seconds across block and stud. I haven't had an opportunity to try it myself, but the theory is sound. The heat will be concentrated at the threads where resistance is highest. You will still need a good way to grip the stud.

Here's a picture of the tool with collets for SAE threads.
1609716
 

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Thank you very much. I've also heard of that electric technique only using a battery charger at it's max setting, Never tried it myself.
 

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Struggling to understand why the resistance will be higher at the bottom thread than where the arc welder clamps clamp to the block or stud. The reason these studs are hard to get out is because there is such tight tolerance between the tapped hole and stud thread. Therefore the full thread depth can be assumed to be in perfect contact with the block.

My arc welder clamp would be lucky to contact a stud I clamped it on for 1/10th of that surface area, so doesn't that mean there would be more heat there?

So would you have to make special clamps?

Then my arc welders cable diameter is smaller than the diameter of one of these studs, so wouldn't the cables get hotter than the stud?

Not sure I understand. Admittedly I'm thinking of my home handyman arc welder ... maybe a 3 phase industry one would make these studs seem puny? Still need really good clamps.
Pete
 

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Then my arc welders cable diameter is smaller than the diameter of one of these studs, so wouldn't the cables get hotter than the stud?
The cable has many strands of wire so lots of surface area for the current to run. According to the skin effect, the current runs along the outer surface of a metal object. So even if the cable is smaller in diameter to the stud. It has more surface area due to the large number of strands.

This might also be why the current will encounter resistance when it reaches the threads.
 

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The cable has many strands of wire so lots of surface area for the current to run. According to the skin effect, the current runs along the outer surface of a metal object. So even if the cable is smaller in diameter to the stud. It has more surface area due to the large number of strands.
But that does not mean that current only flows on the surface. Have you ever seen high power electrical equipment with solid copper bus bars? The very best electrical contacts have some extra resistance and others have much more. Copper has a much higher conductivity than steel and a modest copper wire will offer less resistance than a larger steel stud.
 

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But that does not mean that current only flows on the surface.
Yes, that is true. I should have said current flows mostly along the surface. It diminishes as you go deeper into the metal. And each metal has a different diminishing relationship to depth. I can't remember copper vs steel, but stranded wire does have more surface area than solid wire.
 

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If an interference fit was the only issue, a small amount of heat would expand the aluminum more than the stud. I started with a new block for the Bonneville engine and the studs were easy to remove with little or no heat. After years of exposure to the coolant, there will also be some corrosion between stud and block. The corrosion has high resistance concentrating the heat at the stud/block interface ... so the theory goes.

I've not tried this method, but it's author claims it works well. This type of heating is commonly used to thaw frozen pipes where they're not readily accessible. Again, he's using a 300 amp welder for 10 seconds. The typical 225 amp tombstone may require a little more time.
 

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A solid wire has less resistance than a stranded wire of the same gauge because it has more cross sectional area of copper. The skin effect is not relevant for DC and lower frequencies. This is getting off track but your post #28 is incorrect. Look up wire gauge tables if you are still in doubt.
 

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Stefano
I think that the confusion arises because finely stranded wire has a lower resistance for a given wire gauge, think welding cable. It is because there is less wasted space between conductors and the total cross sectional area of copper is greater.
Jim,
since heat input is proportional to current squared the time for 225 amps to generate the same heat as 300 amps is 1.78 times longer.
 

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I also looked in my old textbooks and found that I overlooked something. Stranded wire bundled together does not take all the surface area of each wire. They appear fused as one, so the surface area is not necessarily greater. Sorry for misleading.
 

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Yes. Never open an inductive circuit when current is flowing unless you want to create a voltage spike and/or sparks.
 

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Since we are having so much fun chatting: My arc welder thoroughly enjoys tripping my garage circuit breaker. I really should get an electrician around to put a 15amp circuit in, like I did in Sydney, but I have found the MIG is not so naughty and while not always as beautiful, will stick the same thicknesses of metal together.

I would so love to modify a Nord engine, but I haven't got a car/need for said engine (I want my 1750GTV to take me back to 1971 every time I get a chance to drive her ... )

Question 1: Any reason why you guys don't weld the "closing the top of the block" plate in and machine afterwards? I would have thought with these now old blocks you would want to re-heat treat them anyway

Question 2: Nobody seems to need or want to strengthen the bottom end. Is this because of the long stroke length meaning high rpm is never going to happen?, although I would have thought that Jim's Boneville engine was trying it's hardest to push the crank out through the sump even @ 7000 rpm. These blocks to me don't look that strong, compared to a Subaru, Porsche or Sud, etc.
Pete
 

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Pete If the deck is welded in how would you change the liners later if needed? I maybe wrong but the stud and threaded hole with corrosion due to dissimilar metal would also create a resistance point and generate heat.
Tim
 
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