I've heard of people using JB weld as an emergency patch for older engine cylinders, so I sure dont think a little vaccume is going to hurt it any.
I used some as a gasket on an intake on an old car when I ditched the old "Thermal coil in the cup" choke assembly in favor of an electric choke, worked just fine.
Word of warning, wear gloves. it dosent burn your skin or anything, but if it gets in contact, it will take a week to wear off. A cheap pair of rubber gloves might let you get a finger in the tube to smoothe out the inside of it and pack a bit up on the inside as an anchor.
JB Weld is great for the things that duct tape cant handle.
