The metal vacuum advance line on my 223 inline 6 has a loop in the center. Is there a reason for this? I have searched but wasn't able to find anything. I think I may have found a possible leak for when the engine was running, I slightly lifted the metal line and the rpms increased. When I let go, the rpms decreased. I am trying to remove the line from the distributor vacuum can but as luck would have it, the darn nut is rounded. Hopefully the penetrating oil and vice grips will do the job. The fun never ends.

 

The distributor has to be able to move to set timing. The loop lets the line "give" enough that it won't be stressed.

Use pliers on the nut, they are a wedge fit into the carb and get tight. You can cut the line a couple inches from the carb and from the distributor, and put rubber hose in between.

The nuts are (sometimes) available from NAPA, p/n WH 6100x3 (at least for flat V8, I don't think they changed)

 

Thanks Ross. Actually, the rounded nut is on the distributor connection. Since I think there may be a crack or small fracture somewhere in the metal line, I'll cut the line a few inches from each connection and run rubber line.

 

Condensation loop