Tapping treads from metric to unc

[hershal]

Hey guys
Quick one
Does any one know what I should retap a stripped m8 hole to as a unc thread?
I know 8mm is close to 3/8 but should I tap a 1/4 unc. I am looking at buying a tap. But for want to buy the wrong one

[Parksy]

My advice would be to keep it metric, just drill out the hole to "clean" out the damaged thread so when you create a new thread, you're not using existing cut metal. Might need to drill the fuel rail hole a little bigger, but you won't compromise strength.
Give this a read so you select the correct size drill bit and tap.
http://geometroforum.com/topic/4334878/1/

Should elaborate, if for example you want a 10mm thread, u can't drill out a 10mm hole. The bolt will just fall into the hole. Using the thread pitch of the bolt you want, u subtract that from the bolt diameter to get the drill bit size you want.

[hershal]

Parksey cheers. I ended up taping to 10mm metric bolt. Got it all back together tonight . Started first go.

[Parksy]

Happy days! Did you ever find out what was causing the engine not to start? How is it running btw?

[hershal]

I can't pinpont exactly what the issue was. As I ended up pulling everything off at once. And then I put new leads, spark plug, cleaned injectors, cleaned MAF, cleaned throttle body back on. Was a good learning adventure though. Cheers again for all your help. It was much appreciated. And being quite new to the whole 4x4 scene it was really good for me to learn some new stuff