I am embarrassed to post this. Very rudimentary. I have never been able to get the kind of brake performance that I know my brakes were capable of. I started out with the GM metric calipers and Corvette master cylinder. I couldn't get them bled out to my satisfaction. Always took a pump to have good brakes. I'll bet over the 3 years I played with that system I ran 5 gallons of fluid through it trying to bleed it out. It got really tiresome. I figured it had to be trying to build a system with mis-matched parts. So with all the "stimulus" money still burning a hole in my pocket I installed a complete new Wilwood disc brake system. D154 calipers front and rear, 7/8" master cylinder, proportioning valve, residual pressure valves and braided flex lines. I cannot get the air out of the system! First hit of the brakes gives just barely adequate braking. One pump then gives great braking. First hit goes a long way down, second pump gives a high hard pedal. So it's not a lot of air, but there is some there. There are no leaks. Annoying as hell. My very first attempt at bleeding the system was using my vacuum pump. That got it close, but not 2 pump close. So I got the wife out to do the pump, hold and release method. That got me to where the second pump gave me good brakes. Driveable but not good. So, then I tried the hose in a bottle with some fluid in it. I pumped a quart through each caliper. Still a 2 pump system. I have re-bench bled the MC a couple of times. I have been taking the calipers off and using spacers to mock the rotor because as mounted the bleeders are not exactly at the top. The bleeders are not far from being straight on top, but I have been removing them to get that last little bit of air. I have tried bleeding the rears with the proportioning valve both ways. I have checked each line individually for flow. Unfortunately nothing has got that last little bit of air out. I certainly don't have the braking performance this system is capable of. I am out of things to try and out of ideas. I know that Wilwood has engineered this whole system to work together, but I can't make it work. Just shoving more brake fluid through it ain't working. This ain't my first rodeo. Been playing this game for more than 50 years. Never had a system I couldn't get bled out. I haven't tried pressure bleeding. Never needed to. Also don't have a pressure bleeder. I have been thinking about drilling a hole in the MC cover and pressurizing the MC to force fluid in instead of sucking it in. That seems a little radical to me though. I would appreciate any insight any of you guys might have!