I have scout axles on my yj (78 axels d44), i put on ford f150 1976 calipers so my yj brake lines would fit directly on there. I have bled the brakes several times and there is no air left in there im 100% sure. I used a yj 4 cylinder booster and master in my rebuild, but i have my il6 laying around. When the engine is off i pump the brakes and the resistance is good. But when i turn the engine on and pump the brakes it goes to the floor. I should mention that i have a amc 360 in there now and i took the vacum off the intake directly just in front of my tbi on the drivers side.

There is no leak in the vacum line. I did the tests to check for booster airtightness as described in my manual and according to them the fact that the pedal goes to the florr when i turn the engine on means my booster is finished.

Can someone comfirm this before i make the change?

Not confirmed, just the opposite really. Your calipers are probably tilted, you can call me and I'll explain or do a search. Booster does NOT sound bad.

I don't think the MC you used can push the volume needed. Might try a 69 vette MC... I think they run about $30 at your local parts place. That particular MC has close to the same dimensions as the YJ MC with more volume and set up for disk brakes.

I would do a quick search in the Hard Core forum for brake write ups....

Best of luck with your project.