Really need help here...BBK header collector stud nut

Does anyone know what size this is? I think it's metric, but I'm not sure. I finally got the car running right, and I need to fix this tonight or tomorrow.

I bought the BBK shorties on ebay and they didn't have nuts. I thought they were the same size as the original headers I took off. I bought some SAE nuts (can't remember the size) and they seemed to work, but you can't really tighten them down. Are they supposed to be metric size? I don't think I stripped the stud, but maybe just the nut because it's the wrong size. It threaded almost all the way up, but it wont tighten like it's a bit too big.

Just really trying to avoid taking the header off if the stud isn't stripped. Would be nice if I could just pick up some new nuts and fix it.


Thanks.
 
Are they made like the Mac headers, where you can unscrew the stud? Hit up the hardware store and buy one nut of a much of different thread sizes and threads and label each one so you know which to get when you find a match. I've had to do this a bunch of times. Luckily i have 2 hardware stores 2 miles from me.
 
Are they made like the Mac headers, where you can unscrew the stud? Hit up the hardware store and buy one nut of a much of different thread sizes and threads and label each one so you know which to get when you find a match. I've had to do this a bunch of times. Luckily i have 2 hardware stores 2 miles from me.


yea, you can unscrew the stud, and I'd have to remove the header. And of course it's the one on the passenger side, and I still have an air pump...lol.