Hy guys, A booster [vacuum] works by applying vacuum to both sides of a diaphragm when it is in non apply mode. When you apply the brakes an atmosphere valve opens allowing filtered atmosheric pressure air to enter the apply side of the diaphragm, one side of the diaphragm now has pressure on it, the other side of the diaphragm has vacuum or less than zero pressure on it. The diaphragm with the pushrod which applies the master cylinder now moves very easily to the apply side. When you release the brake pedal the atmosphere valve closes and the engine vacuum restores both sides of the diaphragm to a balanced vacuum on both sides condition. As to whether or not a 235 can generate enough vacuum to support a booster, of course it can, hundreds of Chev. trucks powered by 235s are or were driving around with hydrovac power brakes, hope that helps.
