When I pulled the head off the mustang I just bought I see this:
http://i12.photobucket.com/albums/a2...n/85fa910d.jpg
#6 is completely clean. My first thought, water... so I check the head gasket and it looks perfect. So then I think cracked block or head. I go look at the head on the table and see this:
http://i12.photobucket.com/albums/a2...n/a706d131.jpg
You can plainly see that #6 chamber has far more carbon on it than any of the others. If water were getting in there, the head would be washed also. So what will wash a cyl and put that much carbon on the head, it doesnt add up.

 

that is weird havent seen that yet [sm=helpout.gif][sm=signs003.gif]

 

that is weird, i would get new heads.

 

I tried finding something on google but couldn't find anyone with the same problem. What was the reason you tore the engine apart? Maybe the engine had a misfire and there was no combustion or a valve is bent or stuck partial open. Might want to try putting some liquid in that combustion chamber on that head and see if it leaks inbetween one of the valves.

 

It looks like the exhaust valve is not working for some reason pushing the exhaust back thru the intake, I just don't get why the intake isn't the color of the exhaust [sm=dontgetit.gif] you should just need new cylinder heads.