Hey Rick, No, the check valve is lately a plastic fitting at the hose to booster chamber connection and when you test it with oral vacuum it will pass air away from the booster but not toward it.Some older boosters with a remote reservoir (usually truck or aftermarket)would have a in the line fitting which worked just as the one we described.Without this when the engine is shut down and vacuum is zero you would have no vacuum assist and panic would likely ensue although anyone MAN enough to manage a stovebolt would do OK without boost but he probably would talk ugly.
If your booster is the type which mounts the MC and has a rubber grommet where the vacuum line connects, the check valve usually plugs in this grommet.These checks do malfunction but should be readily available on the HELP board at local parts store.
