Brake Vacumm

[tbrown5079]

I installed a complete brake booster, pedal, master cylinder etc. from a well known supplier. Nice kit and perfect for my application. 56 Pickup, stock 4.8, disc/drum, GM F body front end. Only problem is, it stops, but I can never really set it down if I want too. If I brake hard 3 or 4 times it works better, but if I don't use the brakes again for a while I get a hard pedal and it will stop, but not as quickly as I would like. They exchanged the booster because they said it was bad, but the new one isn't any better. I have 20" of vacuum at idle and replaced the booster check valve. The brake pedal travel is all good. I am going to check vacuum when running next. The fact that it is not consistent is puzzling. These engines should have more than 18" of vacuum when running right. The kit has a lifetime warranty. Any suggestions? Tbrown