sheared carb mounting stud

[Dag-Navit]

Ok, i knew better but sheared a carb mounting stud on my s4se LHD DH trying to back it out of the intake manifold (weber). Before i start drilling and extracting, anyone got advice/cautions for me before i make things worse possibly? Havng looked through the forums there seems to be a range of ideas. My thought is to drill out and try to remove the stud with an extractor (easyout) first, the stud sheard flush with the face of the manifold, so nothing to grip. For those that are curious, i am removing the body from the chasis with engine in, so need to remove the studs for clearance, would prefer not to remove the head, studs were replaced 20 years ago by yours truly without incident (could f sworn i used neversieze on them ). thanks.

JS

[csjohnson]

I have never tried this on an intake manifold but I use to use this product when I worked as a machinist. IT is called Tap/Out. Basically the product is nitric acid. The Nitric acid will eat iron based metals but it will not eat aluminum. The product comes with clay to build a dam around the stud that is broken off. Fill with a small amount of the acid and sit and wait. Once the stud is gone add the base solution to neutralize the acid before cleanup.

Like I sad I have never used this on a lotus head or intake manifold but I have used it on aluminum and copper. It might be worth looking into.

Chris

[oldelanman]

On my stromberg head the studs go right through the flange and stick out about 6mm the other side. Don't know if your weber head is the same but if so you may be able to get hold of the other end and wind it out from the rear of the flange. Give it a good soak with penetrating oil first. If you do end up drilling it may still be easier to screw the bit out that way anyway.
Don't forget to stuff something in the inlets before you get the drill out !

Good luck. Best regards,

[69S4]

Was the stud actually turning before it sheared off ? If it was then you may have some success with an easy out. If not I think you'll run the risk of breaking the extractor in the drilled stud and be in real trouble. How long is the stub you have to drill?

[prezoom]

Not sure of the availability on your side of the pond, but Eastwood here offers left hand drill bits. A good soaking in a penetrating fluid and a couple of whacks with the hammer and prick punch, locating the center of the stud, may allow you to use a reversable drill motor and the left had bit to walk the stud out with no other action. A little heat never hurts as well.

Rob Walker
26-4889

[Fred Talmadge]

drill all the way thru the stud, use a little heat and the ez out should work. Don't force it or it will break. of course use some penetrant and a few taps with a brass hammer help as well.

[Dag-Navit]

Thanks all for your suggestions.
The stud appeared to turn anti clockwise an 1/8 albeit very tough, i then chose to turn it an 1/8 back the other way, couldn't get it to turn, tried for a better grip and it sheared relatively easily it seemed. My son says he saw it turn, but i am not sure, i think i just twisted it to the point it sheared.
Only a couple of threads protruding from the backside, so nothing to grip really, plus reluctant to use what appears to be a lot of force on that soft alluminum flange.
I wil try the drill and ez out....carefully and let you know. I like the Tap/out idea but leary about the lotus head casting...we'll see, hopefully more conventional approach will get me there. thanks again.

JS

PS, is Eastwood the Eastwood automotive products supplier in the US, i am in CA

[alexblack13]

I'm with stuart here JS. If you sheared off this stud trying to remove it and the stud was in good condition this would suggest it is well seized into the manifold. OR its glued in!! It sheared before it unscrewed! Drilling and easyout method will not work on its own. You will break the easyout and make the job 10 times worse. Heat might work. If you drill it VERY carefully and insert the easyout & load it up carefully. (Consult the manufacturer for max torque to use and stick to it). Then apply heat. Do all the usual soak it overnight in whatever first. Worst comes to worst drill it out and retap. To do this you must center the drilling VERY accurately.

Best of luck with it. Don't break the easyout in the job as they can be a bitch to remove.

Have fun!

Alex B....

[Tonyw]

Dag,

If the stud has broken off as you were undoing it then an easy out or extractor is not going to work and you will inevitably end up breaking one in the hole, you could try heat but I think given the cost of Twink heads I would not.....

If I were in your shoes I would make a jig out of some mild steel plate with three holes a close fit to the remaining studs on the flange and a small hole over the broken stud, bolt the plate to the opening drill out the offending stud to tapping size and carefully tap it out. The reason for the jig is twofold, firstly it will stop crud from getting in the inlet and secondly you will be able to dreil through the centre of the broken stud.

Hope this helps and good luck.

Tony W

[wojeepster]

Use a mill, go slowly. The most important thing is to make sure it is centered. Go up in drill size. Then use easy out.

[GrUmPyBoDgEr]

The Stud may have been Loctited when it was assembled. As others have suggested, heat is probably the best method to try first.
If the Stud won't loosen by trying to screw it out try screwing it in. The exposed threads were probably corroded or even damaged.
Final solution is to drill it out (Easy-Outs can make even more of a problem of the job when they snap.)
I don't even have Easy-Outs in my Workshop!
Even if you end up drilling the whole of the tapped Thread out you can make a good repair of the job with a Wire Thread Insert; failing that a threaded Bush, failing that weld up the resulting Hole & start again with a fresh Threaded Hole. Even "Plastic Metal" may do a good job.

There are many ways of skinning a Cat, as my Dad used to say.
Cheers
John

[Dag-Navit]

Agreed, my experience with easy-outs is mixed at best, i will drill and try it being careful not to over torque beyond the spec ( looking for suitable US or Brit' made tool!). Thinking it through i am now fairly sure that the stud did turn initially, as John mentioned, the exposed threads end of the stud poking through the flange are corroded, i think the stud locked up as the thread turned into the casting , eventhough it was only 1/4 +/- turn. turning the stud through clockwise, winding it in makes good wense, for which i would need and easy-in as there is no stud length to work with proud of the face, sheared a thred below the surface. Is there such a thing?

[gwiz22]

Dear JS,

Please do not try to drill the stud out in situ, whether to use a screw extractor or to re-tap. Getting a hand drill into the confined space is challenge to start and being able to accurately identify the exact centre of the broken stud and then be able to drill squarely throught the depth of the flange is a mighty challenge. I have never been able to drill centrally through a snapped stud or bolt even with the offending item firmly held in a vice using a hand drill. However, I am not a toolmaker or metalworker, just a weekend enthusiast. Remember the stud is steel and the flange is alloy, a fraction off centre and even if you start with a small drill and work up to the tap size drill, it will take out the threads on one side.
I would seriously recommend you remove the head, and either get a machine shop to do the necessary (you have comeback if they screw up) or if you do it yourself, to use a vertical pedestal drill, make sure the head firmly fixed with the broken stud in a perfect vertical position.
I know it might seem a lot of work but if you do drill in situ and go off centre, you are then going to have to remove the head anyway and be up for a helicoil or weld and re-tap.

I hope you don't think I'm a merchant of doom but drilling out a steel stud using a hand drill at a horizontal angle in a tight engine bay seems a tall order and as someone has already stated, twin cam heads are expensive and getting more rare every year.

Good Luck
Graham

[alexblack13]

''Easy in''...steady on!! The answer is yes. L/H variants are available.Normal special order and expensive.AND.. Not g/teed to work.

You now have (I think) all the relative advice required and you now just need to tackle it. The golden rules are when 1st drill goes in...It must be bang on center and in line/parallel to the threaded bore in the head. Can't stress this enough.

Center a 'dimple' made with say a 3mm drill for eg, relative to the bore, NOT the stud. then when happy increase to say a 5mm drill. Again check its centered. If its not, decide which direction it needs to go, and using sharp centerpunch drift a line down the side of the dimple in the direction you want to go. Then drill the 'dimple' a little deeper & check again. It should be better. Do this again if need be until DEAD ON.. If you 'drift' off center it makes drilling it out difficult as the drill will take the easy route and veer away from the stud and drill only the ali, leaving you with a very untidy, off center & out of position hole.

When confident 'dimple' is centered. Fit small sharp, pref new, quality drill, approx 3mm for ist bore. Don't force it and keep the alignment. Use a square and a helper to keep it true.
Be carefull. Breaking the easyout (or a tap!) is a disaster and a real pig to get out. They cannot be drilled and would need to be taken out with special (spark errosion) process.

Expensive!!

Let us know how you get on.

PS..I am assuming you have the head on the bench? Attempting removal in situ will result in tears.Lots of them

[GrUmPyBoDgEr]

JS,
if you apply some penetrating oil, Graham,WD40 or something similar now it will have plenty of time to work whilst you're removing the Body.
There is no "easy in" but it quite often happens that when you start drilling the drill does that job.

Graham,
I think you're being a little over cautious there & you may have forgotten that the Car's body is coming off so access to do the job won't be confined.
If the snapped stud is first Centre Punched as well as possible, starting of with an electric Drill with a small Bit & gradually working up in Dia. to the original Thread Core Dia.
I've found in the past that the Stud usually gives up the fight somewhere along the line & the original thread can be rescued.

Cheers
John

Ooops Alex got there before me!!