ok heres what happend, at school ther was a 1200 a12 and i have my 120y a12 there being rebuilt, i had mixed up the head studs (oops) ad didnt realise that the earlier 12T stud was shorter than the later 12T stud so here i am staging the torque, up to stage 2 at 60nm and "CRACK" and im like "sh!t" hands on my head thinkin i sure as hell hope i havent snapped the b.arstard off, luckly for me the stud was alright even tho it was the shorter 12T stud (no f ing good 2 me) well i got the air gun into the hole blew some thrads out and whipped out the tap, wound it in went all the way and thought good mightnt be so bad afterall, well put the head on, wound it on (with the newer 12T stud) and it got stuck, took the head off and it goes all the way in and im like "what the ####", so i did it again, same thing happened after about 20-30 minutes we realisesed the new thread was slightly off on an angle (sh!t).

so..... after all that what should i do? drill it out find a new tap/stud or tigten it up untill i think "that'l do, before i sh!t it" help i just spen sbout 100 bucks on redoing it so i dont wanna get a new engine, help please

Tom

helicoil it. and check your torque figures - 60nm with an M12 stud into alloy sounds awful high to me.

EDIT: hang on, you're not talking about the studs in the head are you? you mean the thinner head bolt for oil supply to the rockers? you threw me by calling them "studs" - they're bolts.
But the advice is still the same - you can helicoil it and use the original bolt if the thread has survived. Otherwise, you'll need to get another one of those bolts.

sorry for not being clear, the head bolts.

yeah its all good just drill it out to the right size and put a helicoil in it,as long as the hole isnt rusted from the water jacket its, fine. my dad an i put helicoils in all the bolt holes in our 350 chev, they were badly rusted and you could still torque them down a long way.... trust me, ive been putting thousands of helicoils in at work for more than two weeks straight !!!!! ohhh the wonderful jobs u get as a first year apprentice.

Is helicoiling really strong?

The two places where you bolt the gearbox mounting to the body, the mechanics stripped the one hole 3 times already and just drilled it out and made new thread.
When this happens again, I plan to also helicoil it back to the original size as the one bolt is large and the other one is small.
I don't like that and it is at the moment at the last oversize that it can be drilled to.
My dad said that they used helicoils on beetle aircooled engines.
I cannot remember why, but something to do with holes that stripped easily where you bolt the head to the engine block.