The tube is secured to the fitting on each side of the water jacket by a one time use compression ferrule, or sometimes it's soldered to the adapter fittings.. Either way, if you are trying to reinstall the original tube, it's a lost cause. Do not gamble the life of a brand new engine for the sake of a few bucks to buy a new line and do it right. That's false economy. If your engine builder does not understand how the upper engine oiling system works on an old stovebolt, you picked the wrong builder.
Jerry
