50 flathead V8 temp. sending units

[cadillac512]

41ford1
Your attachment shows the wiring diagram for the temperature sensors. On it the diagram shows that contact opens at approximately ? temperature. I am unable to read what the temperature is. Do you have the original to tell me what that number is?
I have a 1950 shoebox and have been running a actual temperature gauge for each head after a rebuild. The temperature runs anywhere from 190 to 210 degrees on each head while driving. I have now installed new factory sensors and it is running in half way between cold and hot. I haven't run it much since. I was wandering at what temperature the double contact opens to send it to hot.

The attachment shows the double contact opening at 204F. Enlarged, it's blurry but readable. So 19Fordy is correct and so is his sender. My '41 Merc with original senders and 180 degree 'stats runs 185-190 degrees on the heads in warm weather and the gauge reads just under 3/4. In cool weather it might run between 1/2 and 3/4...right on the thermostats' beginning opening points. I believe my gauge will read right on the HOT mark at approx 212-215F if I disconnect the double wire sensor and run just the single.


Terry

 

[petehoovie]

Clearer...

 

[19Fordy]

Terry said, "I believe my gauge will read right on the HOT mark at approx 212-215F if I disconnect the double wire sensor and run just the single."

Terry is correct. I have never tried it but, what would the dash gauge read if you replaced the double wire sensor on the driver side with a single wire sensor so that you have two single wire sensors wired in series with each other and then connecting to the stock dash gauge.

Would the temp gauge readings be different when using a stock split core radiator or a single core radiator?

 

[JayChicago]

Thanks for the information but if mine are the same which they should be, the two manual gauges i had in were always reading wrong. Like i said they both showed it running anywhere from 190 to 210 degrees. Now with the factory sensors and gauge it is running about midway between cold and hot. Looks like i need to do some more testing.

You are probably good now. I bought a car with a cheap aftermarket gauge hanging under the dash. Gauge was reading 25 degrees too high! Suggest you use a temp sensor gun on the water outlets to see what actual temps are.

 

[cadillac512]

Terry said, "I believe my gauge will read right on the HOT mark at approx 212-215F if I disconnect the double wire sensor and run just the single."

Terry is correct. I have never tried it but, what would the dash gauge read if you replaced the double wire sensor on the driver side with a single wire sensor so that you have two single wire sensors wired in series with each other and then connecting to the stock dash gauge.

Would the temp gauge readings be different when using a stock split core radiator or a single core radiator?

Since it would halve the resistance, would it make the heating coil in the gauge run hot thus making the gauge read "cold"? (before burning out the gauge maybe?) I don't know...makes my head hurt!


Terry

 

[1950 custom]

The temperature sensors are from Dennis Carpenter ford and the gauges are NOS i picked up from ebay. I have attached the pictures of the package the temperature sensors came in and the mechanical temperature gauges. I don't know if they are made by K-S but they look just like the original. I will get an IR and check the water temperature in the radiator next time I get it out.
A little background although most of it doesn't have anything to do with it running hot from what I thought it was.

My dad had this car when I was a kid. He gave it to me after I married, and it has set in my shop for near 30 years now. I removed the engine last year and had a local guy to rebuild it. While he had it, I removed all the old wiring and installed all new wiring. Before putting it back in the car I put everything back new. I also changed it over to 12v completely including removing the points and replacing them with an electronic ignition. Replaced the generator with an alternator. Dad had someone to put a resistor on the coil so he could use a 12v battery but didn't do anything else. I replaced all the gauges because they had been operated so long with 12 volts on them without a voltage reducer. They are all NOS and I purchased 3 12v to 6v reducer from shoebox central for the gauges. Changed all bulbs and put a turn signal on it. After first starting it up I couldn't get it to run without it running hot in a short period of time. I had it in time according to the ford manual. I had the guy that rebuilt it to come look at it and he timed it by ear, and it ends up being advanced 27-30 degrees if I remember correctly. It ran much better then but still overflowed the radiator. At this point I removed the temperature sensors and installed the mechanical ones and also replaced the 190-degree thermostats with 160 degree one and drilled bypass holes as shoebox central suggest. After this I found out you can't run the radiator full. It has to have a little room under full. At this point it would always run around 220 degrees according to the mechanical gauges. I drove it during the break in period and after I changed the oil replaced the temperature sensors with the factory sensors from Dennis Carpenter. I have only driven it once since then and the gauge ran at halfway between cold and hot. Hopefully the mechanical gauges are off that much, and it hasn't been running hot after all.

 

[petehoovie]

The temperature sensors are from Dennis Carpenter ford and the gauges are NOS i picked up from ebay. I have attached the pictures of the package the temperature sensors came in and the mechanical temperature gauges. I don't know if they are made by K-S but they look just like the original. I will get an IR and check the water temperature in the radiator next time I get it out.

 

[Joe B.]

Get the digital thermometer with aiming laser, then you will know for sure what the temps are where on the engine. I have the 160 stats in my '50 now, with the hole, like you. I also had 190 stats. Original gauge is wired only to the right side single terminal sensor. It reads in the middle when cruising on a cool day and reads around 160 at the sending unit with laser. Once in stop and go the gauge moves to 3/4 and reads 180-190 at the sender. It has been on my agenda to wire it like factory, but still dealing with other priority things. Yes, the coolant needs to be about 2" down with the 4# cap or it will spit some out 'till it's back to that level. I also do the hand on the radiator cap check for a second opinion.

 

[1950 custom]

Took the flathead out this afternoon. The temperature was around 77 degrees.
Here are the temperature readings that I found.
The dash gauge was showing 3/4 Hot. Water temperature in the radiator was 140 according to the IR digital thermometer and 190 and 195 from the two mechanical gauges stuck in top of the radiator.

Other readings from the IR
Driver Side Location Passenger side
173 Tstat Neck 174
152 Hose at Tstat 167
161 Bottom Hose 140
180 At Sensor 197

It seems as though the mechanical gauges are off some. Not sure what to think now. I may try to purchase another mechanical gauge and put it in one side and use the single sending unit and dash gauge for the other side.

Any and all suggestions are welcome.

 

[19Fordy]

I have read that the reproductions of the King Seely Ford flathead temp. sending units
are of questionable quality. One thing is for sure, those Dennis Carpenter reproduction units won't work accurately with your Ebay gauge if they operate on the OHMS Law Principle. King Seely gauges only operate using King Seely temp. gauges. As a side note:Here's a good chart about Ford/Merc 1949-53 thermostats.

 

[petehoovie]

I have read that the reproductions of the King Seely Ford flathead temp. sending units
are of questionable quality. One thing is for sure, those Dennis Carpenter reproduction units won't work accurately with your Ebay gauge if they operate on the OHMS Law Principle. King Seely gauges only operate using King Seely temp. gauges. As a side note:Here's a good chart about Ford/Merc 1949-53 thermostats.

 

[ivory88de]

Looks like I'm a little late to this party, but I hope I can still get some answers/info.
I'm restoring a 47 pickup with a reworked flathead and a 12 volt system (including Gauges) am struggling with how to set up the temp sensing using the 2 sensors that can only be bought in 6 volt. Is there anyway to do this other than using 2 separate gauges and sensors