I replaced the BrakeBooster and master cylinder on my 1978 F250 with a 460 engine and 4 barrell Harley carb. I bled the breaks about 5 times including master cylinder, I have decent breaking power now, but my Brake Pedal is still low, about 1/2 of what it should be. I checked vacum at the Brake Booster, , and it seems to have good vacum. When I apply gas (from idle)the brake peddal comes up full heightfrom half position, but when I apply pressure to brake it goes back down to half position. The truck seems to have a decent idle, not to fast, not to slow, about right. And vacum seems to draw good at Brake Booster.I also checked the vacum hoses andI couldn't find any cracks, holes or air leaks. So, I am thinking it isn't a vacum problem, but the increase in curb idle and responce to the height of the Brake Peddal which in turn does increase vacum to Brake Booster kind of suggests a vacum problem or idle problem, but I have to apply way to much excerleration to gas peddal to get the brake peddal to come up.So a little unsure on it.Of course I know a Tachometer is best for checking idle speed, but any hair brained idiot knows when a vehicle is idling correctly or not, by the sound of the engine and if there is any stalling in the engine or not.Any comments or advice helpfull. Thanks!