Ok here is the deal my 77 K5 has no brake pressure at all I've replaced the master cylinder the booster the calipers and put on pads it needs rotors but I haven't gotten around to that yet and it also needs wheel cylinders on the back I'm going to do those tonight. Just so you know this is my first run in with an all mechanical carb and I'm not really that savvy about vacuum so for my question would the vacuum have any effect on the reason my truck doesn't stop? Or could it be that I've replaced the parts and maybe one or more isn't working properly? I also did bleed the brakes when I put the calipers on and there is no air in the lines and also no leaks at all in the engine bay or under the truck. I also replaced a few line due to them being old and rusty and breaking so I think all in all I put 3 lines on it 1 on the rear that comes from a T-junction to the drivers side wheel cylinder, and 2 up front.