Primer Line Replaced with new Tubing

I've read some articles about broken primer lines and decided to replace the line to the engine.  It is over 50 years old.  The fitting at the gascolator used a compression ring, prone to cracking copper tubing, so I decided to replace it with the correct AN fittings. The AN4022-1 Discharge Nipple and AN780-2 Straight Connector both use the AN800-2 Union Cone Brazed to the tube, and the AN805-2 Union Nut to hold the Cone to the Fitting.

 The idea with the line to the engine was to make it longer so it could have some bends to flex with engine vibration.  Along with being a fresh, not work hardened piece of tubing, this should make it less likely to crack at the fitting.  The bends are made in 2 perpendicular planes to let it wiggle in all directions and, expand and contract with temperature.

 the same bends were made at the end where it joins the tube from the primer.  I clamped the tube, not the coupling, to the engine mount to again reduce stresses on the tube at the fitting.  This way the weight of the coupling isn't causing the line to move with engine vibrations, etc.

The tube from the gascolator to the primer is also clamped to the engine mount tube.

 I had some trouble brazing the AN800-2 Cone to the copper tube because of some "modern" flux I bought, which I have thrown away.  The first step is to clean the end of the tube with Scotch-Brite.  De-burr the end including the inside edge.  A 1/16" drill bit will open the hole after cutting to make de-burring easier.

In the end I used the same flux and brazing metal I use for brazing band saw blades.  The company has gone out of business so I will have to use it sparingly.

It doesn't take a lot of flux.  I put some on the tube then rotate the Cone on the end of the tube to make sure it gets worked inside of it.

 A small propane torch works fine for heating.  I tried my Butane torch but it wouldn't get it hot enough without the help of the propane torch.  It has to glow Red hot for the brazing material to flow.  When it gets hot enough the brazing metal flows nicely into the joint, just like brazing band saw blades.

 A little cleaning with Scotch-Brite and you're done.  Along with other problems the "modern" flux left a hard residue which I could not clean up.

 I took one of the pieces I tried brazing with the "Modern" flux and cut it in half to see how well the brazing metal flowed into the joint.  I pried the end of the tube loose and pulled it back enough to see where the brazing ended.  You can see it made it more than half way up the tube despite the fact that I thought it was a horrible mess and wouldn't use it.  The good flux flowed so well I didn't cut open a piece brazed with it.