318ci engine, blowing out black water / oil and steam

Hi everyone, I just revcently did my first oil change on my 72 Barracuda 318 that I just imported. I put in 4 litres of oil which was about 200mm over 4 quarts.

I ran the engine for about 2 mins then checked the oil, realised it was slightly over and took some out, the dip stick then read, on the full line.

Now when I started the car it emits black water / oil and steam from the exhaust. What has happened? head gasket? allowing water / anti freeze / boil in the the engine..

please help.
Author: cogaussie