Mike,
My original message was a short version of what caused the crack. I left out the part about that I also did not level the two manifolds together at first installation on the car. The differences in the space between the manifolds and engine block were insignificant or so I thought. The differences in this spacing combined with the intake/exhaust "ear" thickness differences. Probably worked together to cause the crack. At least that is what I am thinking.
Bob-A
