First, I'm not familiar with this manifold, but there is some mention around the 'www that it's made in China, and that evidently some folks are getting poor quality control.

However, I don't understand where the leakage is. The only coolant present is the very front and very rear "ports" on the heads, for example, wehre the threaded hole is clear up out of the picture at top left.

Now, if you are referring to the uncovered hole in the middle top of the pic, near the carb, that is the head crossover casting, and has an "inner" hole that IS covered, so the uncovered hole near the carb is OK

Where is the thing leaking?

 

This is a crop of your picture. The uncovered hole is the heat crossover, and is a dead end hole in the casting, won't hurt anything

 

No, what I'm asking is for to clarify the problem. I do not understand where the leak is coming from?

Or are you indeed referring to the area that I described?

Can you "point" to where the leak is, in what part of the original picture that you posted?

 

OK, I wasn't too sure where you were referring to in the picture. The cropped picture I posted shows the hole that is part of the "heat crossover." That will not leak antifreeze, unlenss you have a cracked head.

I BELIEVE you can see the top of that cavity in the head on my old 340 factory intake on one side of the engine, just the way the casting was made