I am rebuilding my MC2100 carb for my '79 CJ5. The engine is a 304 V8. When taking the carb off, a copper tube broke off the top of the engine. It is the tube marked with the red arrow in the picture linked below. In trying to remove the plate that the two tubes are mounted in, the head of the bolt broke off. I am guessing this is a vacuum line. I do not know what is under that plate, so I am hesitant to plug the hole and drill a new one because I don't want metal shards from the drilling to go inside the engine. I thought about drilling out the broken nut but I still have the other to contend with and not sure how successful I will be getting it off. My other thought was to thread a barbed hose fitting into the existing hole and use a flexible hose to make the connection. My first question is "What is that connection?" and my second is "Any other suggestions on resolving it?"