I have been curious about something for a number of years. I originally built my 36 Plymouth in the 80's. I bought a radiator from some company in New Jersey that at that time advertised in Street Rodder. It was a decent looking radiator with a built in transmission cooler. However it was very thick. I built a fan riser for my 318 that put the fan in the center of the radiator. Cooled great! Then I added air. Had to get rid of the mechanical fan and run an electric. Even with a shroud it would run hot in city traffic or at idle. Then it began puking after I shut it off but not in the catch can. I pulled it and took it to a radiator shop and they told me it had minute cracks in the bottom that would open when it got really hot. He said the copper on the bottom was too thin and would flex. They stiffened it and that seemed to solve that problem. In discussing the heating problem he said that it is possible to have too thick of a radiator. I eventually bought a Walker radiator, shroud and electric fan and that seems to have solved the cooling problem. Is it possible that the radiator was too thick?