Being able to do it is one thing. How about what other potential issues are lurking in there that will go unattended to? I'm not trying to say that complete teardown is always a must. But sometimes you come across other things needing attention that are fortunate discoveries "while you're in there."

You may be "lucky" that the head studs are loose. That's how I recently found all of my head studs on my '79 engine. When they were last replaced, they were not threadlocked in place. They only had some nasty smelling gray paste on them. So they were easy to remove. I used two M10 nuts double-nutted on the studs and they all turned out with a mild amount of effort, using a std. 17mm box wrench.

Thanks - I think the 8 hours is referring to the guy that used vice grips to turn the broken stud very slowly.

In 8 hours the average person could remove the engine, separate the gearbox, and get the engine partially disassembled.

To start - does anyone know (or can they please measure) the precise diameter of the head stud channel holes, and the diameter of head studs?

I'll bite...
My 3.2 heads measure 10.5mm diameter at the smallest point. The four holes start out from the top at 24.5mm,dropping 50mm before reducing their size to the 10.5mm.The difference, of course, due to the diameter of the head securing washer and nut. The fourth hole, by the spark plug, provides a bit more access in the beginning, but at the 50mm mark also reduces to 10.5mm. The head studs are 9.84mm at the thread, and 7.64mm nominal for the shank. Good luck with your project.

Excellent info - thanks very much - I can't locate the broken head stud that fell out of my 3.0 engine, but I'm assuming that the dimensions will be the same.

So, the maximum O.D. of the tool will need to be slightly less than 10.5mm, with a tapered I.D. suitable to grip the 7.64mm shank.

I'm hoping to make a prototype removal tool soon ;)

Don't do it half assed, do it the proper way.

Well I guess I'll chime in here. I have been working on a tool to get these things out. Here it is and it is in the testing stage. It is made out of a craftsman extension and works a bit like that toy that you put on your fingers and then you cannot get your fingers out. You screw it on with a bit of pressure and then it really locks on. Looks to be promising.
http://forums.pelicanparts.com/uploa...1332014427.jpg

http://forums.pelicanparts.com/uploa...1332014472.jpg
http://forums.pelicanparts.com/uploa...1332014516.jpg

I think this is a great idea. Imagine being at an event and having one stud break (or you realize one has broken). You can just pack up and go home where you can remove the engine and do a top end rebuild while you are at it. Or you can haul out your trusty stud extractor and a spare stud, do the fix, and you are back in business. Then, when you get home again, you can ponder your next steps.

When I finally raced at Sebring it was a 4,000 mile round trip. I'd have hated to have a mechanical issue rain on my racing. I'd not have thought twice about taking the chance that there was some seal damage or that others would soon break. Speaking of which, I don't see that the copper base gasket would likely be an issue. The C shaped head seal, for cars which have that, could perhaps have gotten damaged. But guys have from time to time reported finding amazing numbers of broken studs and the motor still ran well enough, or so they thought.

So I'd say this would be a fine special circumstance tool. And a challenge to the tool maker. Cut channels for some carbide gripper pieces to be fixed in the ID so it will really grip but can be reused? Though maybe as a special purpose, just one broken stud, tool reuse might not be important.

Excellent! A Chinese-finger stud extractor! Not quite what I was thinking of, but maybe better!

Have you had much success with it yet? What is your plan with respect to application of heat to the broken stud area?

Thanks - very good points and suggestions to consider.

The intent is a one-time use, special circumstance tool, to be used when you become aware that a stud has broken, you don't have time for a full top-end tear-down, but you want to prevent additional damage.

The heat issue is the real killer. If it is a top stud then it's pull the motor time unless you have carbs then it might be worth pulling the fan shroud. On the bottom you can actually heat up the metal air defectors and bend them out of the way to get the heat pretty close to the stud area. Heat exchangers pulled off of course. The tool is really pretty cool, it grabs the stud very hard, almost to hard, I might have to shorten the spiral section. I hope to test it this week on a motor that is out already and see if it holds up.

Thanks :)

The bottom studs are the ones that break; I've never heard of a broken top stud.

The tool does look very cool - what type / size of material is the spiral section made with?

Looking forward to your update, and images ;)

I have been looking at the tool for a while and I believe it could grab the stud.
But doesn't almost the entire torque you apply concentrate to the top spiral? If so, I think it will snap like a straw...

Hi,

How about EDM (Electrical Discharge Machining)? Shouldnt be to hard to make an electrode. The hard part would be to make sure you only machine the stud, not the engine case.

Done right this should only leave parts of the stud threads in the case, which would be easy to remove with a thread tool.



Regards,

Johan

Another suggestion from above - assuming the stud is broken close to the case:

With the engine tin moved out of the way, it might be possible to use a two-piece tool; the lower stud gripper could be as large as the space allows, with a hex socket to engage the second piece - a simple long socket extension that is small enough to pass through the stud channel in the cylinder.

Thoughts?

What I have seen often, is when one or more stuts are broken the head gasket is broken,too.

The spiral section is just the craftsman extension machined down then drilled and then the spiral is cut into it.

This photo was to show how the tool worked. In actual application the spiral cut would be pushed all the way over the broken stud. It will push all the way over the stud but it is just very hard to remove the stud out of the tool so I only installed the stud part way in the photo. This tool still has to prove itself, hopefully it will work. If it breaks it is back to the drawing board.http://forums.pelicanparts.com/suppo...leys/smash.gif

If you need a ginny pig look no further. My lower stud on cylinder 4 broke. I don't know how long a stud is http://forums.pelicanparts.com/uploa...1332137896.jpg
but this is what broke off.

Yes, I assumed that you push the broken stud up above the spiral so that it is supported. I think you would have to make the spiral progressively wider toward the top to make it stronger.

But still, having replaced studs from 2 engines, I know how much force that is needed to make them come out.
There is also the possibility for the tool fail, brake off and jam up the cylinder on the stud. Maybe even cause damage to the cooling fins.

Hi - can't wait to hear the results of your testing - Best of luck :)

Hopefully it will have enough grip to lock onto the stud securely - if not, perhaps my now revised (and evolving) plan to use a solid steel rod with a tapered hollow end + carbide gripper pieces (as suggested by Walt - see above) might work better?

In either case - application of heat http://forums.pelicanparts.com/suppo...ys/flaming.gif is the key process!