water in cylinders?

I have been working on a 76 Chrysler Cordoba with a 360. It has a used edelbrock intake on the stock heads. I got the engine all rebuilt and back in the car, I started it dry block just to make sure it would start and it ran great. I started to put anti-freeze in it, after four gallons the radiator was still not full, so I tried to trun it over and it would not. so I pulled the plugs ane every cylinder was full of water. what could be my problem?