I have a 460 in my 1979 bronco which i believe is out of a 71 lincoln. We finally found a new master cylinder for it which took many weeks and now i have bench bled it and bolted it on and started to bleed the brakes but when i finished and started my car the brake light came on and the only way i get brakes is if i push the pedal all the way to the floor. I basically have no pressure at all. Im wondering if i bench bled it wrong. What i did was put plugs in the ports and attached tubes to them and put the ends of the tubes back into the fluid bowls and started to pump the master cylinder till i saw no air bubbles. They say to pump it until you cant pump it more than an 1/8th of an inch but i pumped it probably 50 to 100 times and felt no difference and it continued to go the full inch even though i saw no air bubbles so i installed it. When you pump the brakes fluide shoots out of the bowl as well as into the ports so it seems like there is air in it again. Also when i install the master cylinder do i not just bleed the bronco like i would normally bleed the brakes. someone was saying something about a needle on the proportioning valve and haveing to pull the needle when bleeding it. If anyone can help me in my problem it would be great cause i need brakes very soon. Thankyou. Sorry for the length but i dont want to leave anything out and give the best description i can. Thanks.
Joseph

 

For what it is worth: I did brakes on my 86 302 including a master cylinder. after completion, With the engine off, they were fine. As soon as the motor was started the peddal could be pushed to the floor. It looked very much like a master cylinder, so I took it back for a replacement, rebled , and same thing. A buddy came by, pinched the big hose going up to master cylinder and problem went away. Unpinched it and problem came back. So, I took this one back as well. Damn same thing with the third one. Another nieghbor came by, adjusted the rod on the booster that contacts brake pedal, and all issues were resolved. Hope this helps.

dennis