Ok, it appears you and I have gotten the education we were looking for over the past 2 days. The gentleman that called yours 1/2 water heads I would say is correct. There's just not much room for water to flow thru those tiny holes. Mine has what appears to be normal water jackets except they don't have the steam holes across the bottom. Without the freeze plugs in the end you can look right thru them and the water passages are large. And the upper water passage is large also. Based on what we know now I don't think you would want to use your heads on an application that was going to run for more than a few minutes. I love KB and it's been a pleasure working with you on this. For some reason my photos won't attach. I'll shut down and try again.