[DanEC]

[quote=DAVID GAGNARD;1256949]Unless you have a serious leak in the line/caliper (which you would have seen fluid leaking from by now) the source of your bubbles are the threads on the bleeder itself................I've seen this a hundred times...
It will not hurt anything,once you get fresh fluid coming out, then have someone in the car manually pumping the brake pedal and do the last bleed the old fashion way with 2 people and be done with it..........QUOTE]

After reflection this has got to be the issue and I think where I'm going with it. Even just barely cracking the bleeder until fluid movement is barely noticeable and coating around the base of the bleeder screw with grease it still pulls air into the line. It's surprising but it only starts after the syphon column reaches maximum head and then the dam breaks and here come the bubbles. It's got to still be pulling air around the bleeder in these old, rebuilt calipers. My wife has been put on notice for brake bleeding duty when the weather cools a little. Speed bleeders is another upgrade I can work on once I get this thing together and running.

I tried pressure bleeding the one bad caliper but it just caused brake fluid to run out around the bleeder screw even with it barely cracked open.

Kevins2's comment about raising the nose to get air out of the master cylinders does kind of concern me. I don't think it's practical to bleed these things separate from the rest of the system - at least that I know about. Guess I'll give that a try and rap them with a wooden dowel to try to move the air along.