I'm pretty sure it has something to do with running it with no water. It IS a water cooled engine after all. I can't see it being a leak in the intake or crack in the head, even with no rings the pistons wouldn't allow water to "gurgle" down that fast. It nearly has to be a LARGE gaping crack somewhere in the block or somehow the gasket intersects water and oil somewhere. I'm not exactly sure which evolution the '61 is as far as rocker oiling, but there may be something there.
