Brake canisters

You give it manifold vacuum at the ribbed fitting and the brake hose/booster goes to the black fitting. It goes inline between the motor and the brake booster. All it basically does is generate a really strong vacuum source over time to create a strong negative pressure. You can then use this with your brake booster to create strong braking when you need it. It probably has some valve inside that allows manifold vacuum to pull air out but not release pressure through the same fitting.

i have the same canister, it seems to work ok, nothing fantastic though. i had some very small vacuum leaks that i finally found between the upper/ lower intake manifold. i bought a vac gauge and to this day the best is around 11-13 inches of vacuum, with the idle at 1000, with a 232/240 565/574 cam. as for the install, crazy pete is right, there is the ribbed peice in the top with a check valve which only allows vacuum in and the other fitting i routed to the brake booster. the other hole i used a pipe plug with some teflon tape. it did make a noticeable difference after the install, but check for vacuum leaks, cause thats what made the major difference. take some intake aerosol cleaner and have the car running, spray down the vacuum lines and the seals on the intake, if the idle changes there might be a leak there when you spray it. also poor vacuum could result from improper adjusted rocker arms that are too tight causing the valve to stay open just a fraction.