Disc brake vacuum question

It takes no more vacuum to operate a booster with disc or drum. The difference is in the brakes, not the vacuum booster. You keep asking the same question over and over again, yet have given nothing to go on. So let me ask you one. What is your manifold vacuum reading at idle? Before anything can be answered, that must be answered first. Your problem could be anywhere from a low vacuum reading due to the camshaft, or a vacuum leak, to a bad booster check valve or bad booster itself. Since we are all at a disadvantage and cannot stand there and diagnose your car, how bout a little help from your end?