1956 is the only Year Gauges were designed to work on direct 12 Volts. The 1957 reducer can be used on 6-12 Volt Conversions as well as 1957 and later 12 Volt Systems.

71% of original size (was 708x19) - Click to enlarge  71% of original size (was 708x19) - Click to enlarge

get a dash voltage reducer from 1957 and later forcer. i installed 1 in my 49 mere 12volt all gauges work now,even gas gauge

We checked the calibration of the sensor and it appears correct so the problem is the gauge.  At around150 degrees the sensor is reading the correct ohms but the gauge is pinned at hot.  Gotta call Bob's speedometer and ask him why.  

Either the sending unit is incorrect or the gauge is defective.
The gauge in the '56 that sits in my garage was repaired by Bob's Speedometer. When the key is on, it goes to COLD and stays there until the coolant temperature goes to 180 and it moves a little off COLD. Then at 190 it will move 1/4 of the gauge and at 195 it will go to half. I've never seen it go any higher  than that. Have electric fan and only use it at red lights here in Hot 'n Humid Florida.

SIDE STORY: The temperature gauge that was repaired by Bob's Speedometer came out of the dash of my first '56 Ford Fairlane that I had when I was a  teenager.  I sold the car to a friend who wrecked it but form some unknown reason tore the dash out of the car and put it in his grandparents barn. It sat there in that barn for 58 years.
Last year, I was up around Detroit and found out the dash was still there and I gave the new owner of the barn a 6 pack of Bud Light for the dash and put it in the trunk of my 1956 Ford Crown Victoria and it now hangs in my garage here in Florida. It had the original temperature gauge, so it was sent to Bob's Speedometer to be repaired and it is now working just fine in the Crown Victoria. If that temperature gauge could talk....etc.
Thanks for your time,
Tim 
Hot 'n Humid, FL
33706

ONE FINAL ENTRY!!  Temperature sensor calibration

When I said everything now works fine, I meant when I turned on the key, the temp needle swung to the COLD side.  However after a short drive the needle gets penned up at the hot position.  There is no indication the engine is overheated so I assume the sensor is out of calibration.  Called Mac's (where I bought it) and they gave the following information which should be very useful to other members.  Haven't checked it yet.

Engine cold      14-20 ohms
160 deg            35 ohm
175 deg            50 ohm
212 deg            open circuit or infinite ohms

i want to close this one out.  I replaced the temperature sender and everything works fine.

Thanks guys..

Okay about Bob's Speedometer.......
They repaired my temperature gauge and it stays on COOL until the temperature gets to 190 degrees. Then it read 1/4 on the gauge. Around 195 degrees 
it will read 1/2 on the gauge.
I have and after market set up with three readings: Temp, Volts and Oil and an electric fan that is never on when doing 70 mph on I-75. Some times it is turned on when I wait at long traffic lights in the city in the summer.
You might let you car get warm and see if your gauge will move just a little.
good Luck
Tim
Waiting Room for Heaven, Florida
33706

Please remember if you have a Pertronics ignition do not leave it run very long without the engine running.. If the gauge does not move very quickly off the "H" then start looking for the problem. Good Luck 
PS I had more problems with the tank float than the sender or the gauge especially getting a near correct reading.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

It was Bob's Speedometer who refurbished my cluster..

I've tested the gauge with a 9 volt battery and had luck.
Also, I've been sending gauges to Bob's Speedometer in Howell, Michigan for years with no complaints.
They fix 'em and I install 'em.
bobsspeedometer.com
Tim
Wrinkle City, Florida
33706