As noted in the 1947-48 Illustrated Parts List Book, the sender unit for Water Temperature is different from the type used on the Kaisers. Check this book for the exploded view which will show you where to find the sensor and the lead back to the gage. If the gage shorts out, normally the gages swing to full hot as soon as you turn the key (before you start the car) and it stays there. Otherwise, if there is a thermostat in the cooling system you should start to see movement after a couple of minutes. Check the BLUE COVER 1947-48-49-50 Factory Shop Manual for more information on the cooling system set up.
I am assuming that you have both items, valuable tools in their own right for the repair, restoration and upgrade of your vehicle. If you do not, both books show up on eBay from time to time, or members can run a free WANTED ad in the KFOCI MONTHLY BULLETIN.
If everything is working properly, the gage should sit around the 170 mark.