I read a post a few months back where a guy suggested using gravity to bleed the lines.
I havent ever tried it, but the dude said he'd open up all the bleeder valves, fill up the master cylinder, and then let gravity pull the fluid from the master cylinder down thru all the brake lines.
I dunno how well that would work, since on all the trucks i've bled the brakes on, the lines were usually lower than the master cylinder and individual brake cylinders.
I've also read that "professionals" use some sort of vac system to pull fluid thru the lines.. but I haven't ever done that either.
When I have bone dry lines, from either a fresh install, or from just sitting, I fill the MC up, put the cap back on, then pump the crap out of the brakes.
In both my '46 and '50 this results in some pressure build up of both air and fluid.. not so much you really feel it in the pedal, but enough that if you have a vented MC cap, it'll start squirting like a lawn sprinkler.
Then I have a helper hold the pedal to the floor, and I go to the wheel furthest away from the MC and open the bleeder.. which usually sighs a little air and a dribble or two of fluid.
Then I start standard brake bleeding procedure.. have the helper pump three times then hold to the floor, then I open the bleeder till all I get out of it is clean fluid.
Brakes work in my '46 2 ton with vac assist with or without the engine running, so fluid should be able to pass thru it regardless of the engine ever having been installed or run.. but thats just a guess.
