This block is probably a bypass/ballast resistor. You can't see the coils in that back. Anyway someone has bypassed the bypass. The reason lies in if you have a 12V or 6V battery, an internally resisted coil or not (ink stamped on case), a foot start or electric solenoid..........don't disconnect the jumper until we can figure out what you have.
Also you need to describe EXACTLY where the wire to starter goes. What terminal?
Also you need to describe what wires are coming into the ceramic block.
It could be just a junction block. A place to terminate wires. A pic or two would help.
A 1951, 216 should not have had a ballast resistor, so that is curious.
