On my sedan I run one, but did two on my roadster. My left side runs 20 degree hotter until a really solid drive and heat soak then almost catches up. Right side still runs a little cooler. Intersting.
I have the stock gauge connected to the stock "single pole" sensor. I have an aftermarket mechanical gauge in the other head. They usually read just about the same, but am kind of surprised that the stock Ford electric gauge seems to react faster than the mechanical gauge.
Not sure the meaning or how it worked , over 40 years have passed .my Flathead had 2 senders , left 2 wires one from gauge one to the sender in the rt head . This was bone stone stock from Henry’s build shop .
The stock system was run pretty much as explained by Shivasdad above. One of the senders had a single wire connection and the other had 2 connections, one for the gauge and the other to connect to the sender on the opposite bank. My experience with my own flathead has been that the stock gauge was not very accurate at all so i replaced it with a mechanical gauge which is spot on. Although the two banks are fully independant of each other , the coolant mixes both sides together in the radiator. A single gauge should be all that is required. I doubt that having dual gauges has really saved an engine. That being said many of us will install dual gauges for our own piece of mind. After all, it is our baby!
The King Seeley gauges Henry used were based on heat caused by current flow through the sender to ground. More current more heat on the bimetal sensor in the gauge and make the needle move up the scale of the face. The dual senders used a common wire to the gauge. The hotter side would allow more current flow to ground and electricity being electricity will follow the path of least resistance, so the hotter side would always control the gauge reading. The basic problem with this system is that even though the gauge was observing the hotter bank, the driver never which side it was. The only way to find out was to disconnect the single contact sender. If the temp went down, that was your hot side. If the temperature didn't drop, then the dual contact side sender was the hot side. In the beginning, Henry Ford went to D'Arsenval in France to have them develope gauges for his cars. D'Arsenal use only the finest materials and practices. They were only able to get the cost down to 25 cents per unit. Since Henry footed the bill for research, he took everything to King Seeley and they cheapened everything up and produced a D'Arsenval design for, if memory serves me, for 11 cents. It worked good enough to go from Model A until 1985. Except for 1956 when Ford went to 12 volts. That didn't go so well and for 1957, Ford went back to the King Seeley 6 volt gauge and used an instrument voltage regulator to drop the gauge voltage back to 6 volt pulsed power. I worked for a Ford dealers and remember the many problems with gauges in 1986, when Ford changed over to magnetic gauges like GM used. Ford, being frugal (read that cheap) used the dual sender/single gauge set up on 8BA figuring it was close enought. In 1954, with the introduction of the Y block, a crossover manifold was incorporated into the intake and only one sender was necessary. If it read hot, it meant the engine wa hot just like all modern day engines do today. So, if both senders and gauge are functioning correctly , you should have no problem understanding if the engine is running hot. BUT, for peace of mind, it never hurts to use one gauge per bank.
Things are more complicated on a genuine 32 with the stock "thermometer style" gauge. Here my home made dual temp gauge, made out of 2 original dismanteled units. I still have to improve the reading by adding a simplified scale. This specific dual gauge was time consuming to create, however, more complicated was to insert both pick-up temp bulbs in the stock 1932 flatheads (that have no such bungs). But now, I have my two banks temp info, what is peace-minding, and still with original looks and function.
Now how many of you have them hooked up? Haha most the time I see a dash full of cool gauges they fire it up and none of them move
I have a 1953 Mercury Monterey with the two different sensors. I had to replace the one on the passenger side cylinder head. It then started to read correct. But the sensor on the left makes no sense at all, as this one only switches over to a full on mode when the engine is overheating. So the left engine head is only being monitored above ~212 Fahrenheit. When I get the fuel system problems figured out, I think I will get another passenger side sensor and install it in the driver's side cylinder head. Then I plan on making an electronic switch that will toggle every 2 minutes or so from one sensor to the other. That way I can see both temperatures. I am thinking of putting a Red LED (R for Right cylinder head) to illuminate when the right head is being measured. I would think the 2 minutes should be long enough for the temp gauge to stabilize. I'll post the results when I complete the electronic switch.
I put a sender in each head and two gauges in the dash. I had to drop the voltmeter since there was only holes for 4 gauges plus the speedo. I would like to add the voltmeter along with a boost gauge but I havent come up with a neat way to mount them yet.
I don't think this would work. The dual sender was just a switch that would open up and send the gauge to "Full Hot" if the left bank overheated. I've never tried it, but I believe disconnecting the single pole sensor would also sent the gauge to "Full Hot".
Looks like those gauges are reading perfect. The water temps are very close to the same as well . Oil pressure is reading over 30 at temp ,,,,at idle. No foot on the gas pedal,,,,,LoL. Tommy
Westach has a dual temp gauge, looks like a little like an aircraft gauge, and is mechanical with dual bourdon tubes.
Many oval track racers would run an oil temp gauge, as a coolant level below the themo- couple or defunct sending unit will render a water temp gauge an erroneous reading until the heads/block are hot enough to elevate a reading, by then the damage is already occurring...the circulating... oil temp rise would hopefully save the day......
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