I just installed one on a lensboard, and it works fine. Here is how it works, if it is a factory made flash sync model. Most all Packard shutters (and all with factory flash sync) have the little pin-hole in them that takes the in-out pin that is mounted on the front of the lensboard. The function of this pin is to switch the shutter from "bulb" to "instantaneous". With the pin out, the shutter will open when the air-bulb is squeezed.(pressure) It will close when the air bulb is released. (vacuum). No flash trigger on bulb.
When the pin is pushed in..the shutter will provide an instantaneous action, with the shutter opening and closing on one air-bulb squeeze. Shutter speed is between 1/20 and 1/125 depending on shutter size and pressure on the air-bulb when you squeeze it. When set to "instantaneous" the flash should trigger. If it does not, it is a simple matter to separate the halves of the shutter metal case (4 screws, sometimes 3 screws) and adjust the metal contacts of the flash trigger. How this works is very obvious when you take the shutter apart. The bottom line is that you have to have the "bulb-instantaneous" pin in "instantaneous" position for the shutter to trigger the flash. If your shutter didn't come with this pin (mounted to front of lensboard) you can make a makeshift one from a large paper-clip.