Worried about going to far into the HEAD

I am doing a heli coil thingy on my head for the exhaust manifold. I am drilling into the head, (21/64 bit) And I just don't know how to tell what is to far. Then I can't tap it by hand. Bah, I am sure I am just freaking myself out, I jsut don't want to fuck up my head and everything else. thanks

Stick something into the bolt hole in the head and mark the depth with tape. Transfer that mark plus a 1/64 to your drill bit(wrap the tape around the bit @ appropriate depth). As long as you dont go past your mark you should be good to go. ;)

so what happens if I go to far from that? lol, doesn't the bit also get smaller as you drill?

Dude if you cant follow those directions you might want to consider a machine shop. ;)

Also, your drilling alluminum with a steel bit, the minimal amount of wear(if any) to the bit is negligable.:thumbsup:

well I did that with tape, I have drilled in one hole pretty well, it is still before my tape mark, I am freaking out because well, it got real cold outside, my garage was closed, and I have like no room between and the garage door infront of the car, so im getting frustrated, the tap I have kinda can be hand tightened but it for so much, I think I am rushing it, which is bad, it's my frist time doing this sort of thing, bah just don't want to fuck upp, im going to wait for tommorow to get warmer.

so what happens if I go to far from that? lol, doesn't the bit also get smaller as you drill?
You are sofa king retarded. The drill bit gets smaller? Think about it..., if you need help (cause your brain doesn't work right) I'll help you tomorrow. You can use a socket for the tap if that gigantic tap handle doesn't work.

yah giaganto doesn't work at all, I gave up last night becasue I was rushing shit, so I thought about it, and went inside, because i don't wanna fuck something up, call me today, I just waited fucking 1 hour for prom tickets.