How good is this stuff??
Made a bit of a mess with trying to helicoil a few cam cap studs on my engine. The studs weren't torquing up and were pulling out so I helicoiled them, well tried to and managed to bore holes and thread too big for the helicoil to fit proper. Could I jb weld the threads in the hole put a helicoil in, jb weld the stud and put that in then? Would it be secure?
Never used JB before but have used araldite for other tasks which is kinda crap- same stuff diff name??

What studs? How much torque ar the bolts done up to.
I think we need a lot more info.

I have used JB weld and its good. However never used it on studs that will habe a lot of torque applied.

Any pictures of the offending thread / engine etc.

I would use it on a get me home bodge but I would get the cossie casting welded and do the job once

Its a cosworth YB.. Offending studs are the ones sticking up in the pic. The nuts are done up to 22 ft lbs. Near half are suspect failures, someone went to town on them..

take the head to a engine machine workshop and get it done properly. All you'll do is waste money trying to fix it and every time they come lose or fall out you'll have to fork out even more or even wreak the engine

Ah... A Cossie head. Don't bodge it, weld up and have new threads cut properly.
Last thing you want is a scrap cossie head, or a completely blown engine when it gives way and trashes the crank, pistons and block as a result.

Thats not a cheap ten a penny head. Do it right first time. It will be cheaper in the long run.

Trouble, as I see it, with any repair on the studs is that they hold the caps that secure the cams, get them the slightest bit out of line and your in deep do do! Looks like you may be looking for a new head, or at the least a very expensive repair done profesionaly. Not what you want to hear but! Ray

There was do do involved when I realised the problem...

There is basically no room for a misaligned cam cap. I could bore the cap holes so there is a slight left to right adjustment that will allow the cap to settle centrally on the cam when torquing up.
Another option is to use an m10 stud that fits the larger hole and have the top part machined down to m8 and threaded to go through the cap.

I think the point is that this is a precision repair that needs to be done by folk who do this work all the time. I’m all for refurbishing engines yourself but when it comes to repairing damage like this it is best to do it 100% correctly with the correct tools or you may just lose the whole engine. The cam takes quite a pounding and a hell of a lot of vibration which would just break up any JB weld over time. I have used it myself and but for just ‘gluing in’ pipe fittings to intake manifolds where it worked very well but was not under any great stress.

JB weld is more advertising Hype than substance.
Take your pore old head to a competent shop for a threadsert fitting.

a true line and centre can still be achieved by measuring so if you take it to a machine shop proper engineer they will make note of all hole centres prior to doing any thing, I wouldn't recomend elongating holes or wideneing holes in end caps at this will only affect the overall strength. Have them plug welded, ground and retapped there may be enough meat in the head to have a helicoil inserted

[Edited on 6/3/11 by austin man]

i had an old fiat twin cam with a problem similar to that. tried all sorts to sort it but ended up welding inside the holes then reboring them and tapping them.

i watched the chap do it while i waited. he fixed the head to the machine lined the tool up with the hole then raised it out the way. welded up the hole but not fully, just enough to make it smaller, let it cool then brought the head of the mill down and re drilled it then tapped. he did 7 altogether and from memory it set me back about £150 but was well worth it for a proper job.

Thanks for the advice chaps... just need to find a capable engineer.

So I taped out the holes to accept a high tensile m10 bolt and had custom studs made to fit with an m10 bottom and an m8 top.
Went over all the caps individually making sure when tightened down they weren't gripping the cam are were aligning proper. Some needed addressed slightly prob cause the pilot hole and tap were slightly out... Some high strength bearing retainer on the new threads and I think I have gotten away with it... well its back on the road now!