I put an 86 E350 Master Cylinder on my YJ the other day, but I don't have any brakes until the 3rd pump. I am running axles front and rear out of a 1975 J20. The Brakes are stock drums in rear and discs in the front off of the truck. I have bled them several times and put new calipers and pads on the front. I tried adjusting the rod in the booster but by the time I get brakes the front wheels don't want to turn.
Could the stock YJ Brake lines be too small, or is there a check valve somewhere that is supposed to hold pressure? This thing is deadly with a 401 and no brakes, but it sure is fun.