I did a full engine rebuild and now I'm putting the intake manifold on. only problem is that I looked at the gasket and saw that there were only two cooling ports open, in the front of each side. So being the genius I am I cut about a 3/4 inch hole in the two back passages to let coolant through to the rear of the heads, because that's what an intake manifold gasket is supposed to look like right? (lol). A friend of mine told me that those passages are supposed to be closed so that the coolant is forced into the outlet in the back of the manifold. Do I need to put new gaskets on or will it be fine with the back ports open?

 

It'll be fine. Some intake gaskets have them open, some closed. But, most intakes are blocked off back there, so it doesn't matter either way.