I got a used header and it seems to have a lot of carbon build up, in the area where it meets the engine block. I'm just wondering what could I use to clean some of that carbon build up.

 

Brake parts cleaner will dissolve it off. If you don't want to use something so harsh(no problem using BPC) you can use simple green although it'll take a lot more effort to get it off.

 

Okay thanks, I was thinking maybe some CLR might work too.

 

I got this long metal pipe cleaner type of tool, it has a metal brush head on a flexible long handle. I don't know the formal name of it but it works great sliding into each header primary tube and it goes all the way down to the secondaries, pulling and pushing while turning the tool and it scrapes the inside of the header clean of carbon. Compressed air works well too if you have a decent spray nozzle and a compressor, you can blow the carbon loose. You could also try brake cleaner if you can find a spray can with strong spray pattern.