Oil pressure sending unit thread adapter
Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models
Sometimes an old engine will have an American made oil pressure sensor installed. In my case the conversion was made to work a needle gauge. For simplicity I wanted the original style pressure switch that controls a light. The problem then is the hole; it was over-taped to accept a 1⁄4 inch pipe thread that matches the sensor. The replacement metric switch has a 12 mm × 1.5 mm thread.
Trying to modify some brass fittings to make an adapter didn't work. The solution is modifying a 3⁄8 inch air line quick-connect plug. It has the male pipe thread and enough material in the body to drill out and tap. It's plated and looks good.
Cut off the top and drill into the body with 13⁄32 inch drill and tap with 12 mm × 1.5 mm.