Stick your finger in the water transfer holes on the deck and feel the casting around the head bolt . They are not cast deep enough or big enough . With the stock 7/16 or if you go to 1/2 head studs there is only .750 thread engagement and no casting left to go deeper , it just goes nowhere . The thread cast is just stuck on the cylinder bore and 60% is hanging in the water jacket with no support . The KB is a solid deck with the water transfer port drilled the lower water gallery .