Big Block heart attack

Just brought a dart with a 383 in it, I have never had a Hemi before but I just went to change a hedder gasket and when I removed the first bolt at the front of the engine coolant pours out, went to the other side same thing.....what the ??? I have only had chev cars and never would of thought I would see this...is it normal?? looks like the bolt would go into the jacket as there is a plug nearby.

If its normal I will no doubt need to seal the bolts when they go back in.