Bleeding Brakes

I agree I've never run into this problem before. This valve is new I just bought it. I'm tempted to run a one peice line to the back but I'm dont want to have that lockup problem. The factory didn't put them on in 67. I guess they found there was a problem and started in 68. Maybe some one on here has run across this before. The reason I asked about he engine running is because the manuel says you need to have 500 psi to test these valves. Thanks for your input.