51 KY 3100 the bed is done and I think the roll does not go completely around. There is a a gap where air can get in. The plugs I made can be removed in a few seconds if need be. As far as rust prooofing goes, one trick we use on float planes in the motor mount (which is a many tubed structure like a birdcage) is to drill small holes and pour in LPS oil. We plug the holes and then shake, twist, roll the unit so the oil goes into all the tubes. We drain it and replug the holes. As these are flown mainly in salt water, the trick works very well.
