hi all ,just joined , and need some assistance with my 67 xr7,the power brakes work fine , the first time you hit the pedal,if you pause alittle , and have to hit the pedal again,no power assist,like there is zero vacuum to operate the unit,vav gauge at the intake is 15, the only items drawing vac are ,pb booster ,trans,vac advance,???
Welcome to CCCF!
15 inHg is barely enough to operate the booster. I think that is your only problem. What are your cam specs?