rethreading manifold stud holes

one of the studs in the head of mt new engine appears to have been pulled out by the previous owner with a fair bit of force, leaving it in a funny V shape more annoyingly,so the standard size manifold stud will never fit
am i alright to just re tap the hole larger? i tried to re thread it the other day, but this didnt work as my cheap halfords set wasnt man enough for the job, so if anyone can link me to a very strong (preferably single, i dont wanna buy a whole set!) m12 re threader, tap, whatever the correct name is that would be great
cheers all

If you're not 100% doing it, I'd pay to have it helicoiled.

Just come into work and one of the mechanics immediately said he could do it if I got a helix oil kit for it, cheers mate

Dunno if anyone can tell me what the manifold studs are? Guessing M8 x 1.25

M10 x 1.25

Fuck sake. Just bought M8 x1.25, lol cheers tho

Sorry Tom, but M8 will always be useful somewhere....
You did mean the exhaust manifold I hope.

No worries at all mate, yeah I did mean exhaust manifold. Really bloody annoying motor factors aren't open normal hours on Saturday. I could have had my engine all back together over the weekend! Sods law isn't it