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Aloha,

I would like to add a cylinder head temp gauge. From the pictures below can anyone tell me which is the hot ignition terminal wire I can connect to? Will a 12 volt neg ground Faria gauge run on my 6 volt+ ground or am I wasting my time? Any help is greatly appreciated.

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If you have a volt meter or test light, it should be pretty easy to figure out which terminal is which.

What's front with the stock temp guage and sender?

It is doubtful you will be able to use a 12v electronic gauge directly powered from a 6v positive ground supply. I doubt your new gauge uses the old bimetal or even magnetic operation like the original gauges Packard used so the issue is not only voltage but also the solid state components inside the gauge. Solid state is polarity specific and I suspect the gauge will not have the added components needed to make it universal. Most gauges today also use LED illumination and if that gauge does, typical implementations of the LED will be another polarity specific item. The LED will probably have a current limiting resistor calculated for 12v and will be dim if it lights at all on 6v. Since there is only one wire to power the LED and only one coming from the sender, the gauge will most likely be needing a negative ground. You might check the paperwork carefully to see if there are specific requirements.

There are some 6 to 12v converters which can work with mixed grounds and convert a 6v input from a positive ground car to power a 12v negative ground electronic item. I suspect you will need something like that to power the gauge and will also need to power the LED from it rather than the illumination power coming from the dash light circuit. The other option which would give you a lot more flexibility would be to get a purely mechanical gauge.

Another question would be where you are going to place the sensor. If you are going to keep the original gauge and sender then there are limitations on where you will be able to get a reliable flowing water temperature unless you are not measuring water temp but strictly the surface metal head temp and plan to somehow mount the sender on the head surface.

Here is the back of a 54 ignition switch showing the terminal designations. IGN is the terminal closest to the lamp and bracket. It will be hot only when the key is turned to the right or run position. ACC will be hot in either key direction.

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Thank you for responding BigKev and Howard. My original water temp gauge and sender work fine and will remain the same. The Faria temp sender just mounts flat on top of the head. Ideally , because the of the aluminum head, I wanted to monitor it's temp. The Faria gauge is fairly inexpensive but only goes to 120 F degrees so I'm probably spinning wheels. Classic Instruments does sell a vintage cylinder head temp gauge with a microprocessor and is very expensive. Neither actually say they are 12 volt. But the lights are LED. I was not going to connect the lights. The Classic looks like the 14mm thermocouple sender goes around one of the spark plugs?

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Classic is a reputable company and their products are decent quality. Not familiar with the Faria but if that is the one you are considering you might contact the vendor and explain the situation. See what they say about voltage requirements and if a converter would be needed. If so maybe they have one to recommend. There might be another question about the black face gauge though.

The proofreading on the writeup description and silkscreening on the black gauge face seems a bit lacking. Simple errors which are easy to see makes me wonder about how good a quality product it actually might be with things you cannot see. Believe the temp description in the writeup should say 60-220F and not the 120 printed. The temperature identifiers silk screened on the gauge face under TEMP identifies the Centigrade numbers in white and Fahrenheit in blue. That should be reversed because F is actually the white numbers.

The max 220 temp range might be a bit close for the head temp but if all is normal I think it could work. A bench test done by a poster on a 52 Packard sender and temp gauge has that combination maxing at about 220 degrees when the needle is pegged at the hot end. No idea how much warmer the aluminum could get over the flowing water temp but I would think if everything is normal and there is airflow over the head it should not go over about 200 in operation. I do think it would go higher when the engine was turned off after a hot run though. No idea if there would be a max temp the sender can withstand without damage.

Thanks again Howard. I've have pinged both vendors. Radio silence so far. The Faria does appear backwards. To keep things cooler I disconnected the fresh air tubes so the air flows into the engine bay and put 5" filters on the ingoing cabin tubes. Aside from basically the gauge not working with the 6 volt, by connecting the power wire to the yellow IGN wire and pressumably it's a 12v neg gauge, do I risk any damage to the rest of the electrical system?

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Summit racing markets a number of mechanical temperature sensors, those might work, and then you wouldn't have to mess with any wiring. They are also cheaper and more reliable.

Summit Racing Mechanical Water Temperature gauge

Good afternoon...We use a mechanical guage on our 1949 Deluxe and it works great. Ernie in Arizona

What is the point of adding a gauge and what is the purpose of modifying the fresh air inlets?

The point of adding a cylinder head temperature gauge is to monitor the surviving ultra rare hard to find 359 aluminum cylinder head. Which is different than monitoring water temp? Modifying the fresh air inlets is to allow more air into the engine bay. Pressumably to make things cooler? What am I missing here Mr. Goat? Any who, Westach has a 6 volt+ CHT gauge with a 14 mm J type thermocouple that goes around a spark plugs. We will go with that. Thank you for all those who showed interest and helped.

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