I'm currently working on a Cadillac flathead powered Model A, and somewhere in the annals of the HAMB was posted an analog two-needle electric coolant temperature gauge. I'd really like to use one of these, but have been unable to find the one I saw by doing several searches. The Cadillac flathead has just a single water pump, on the passenger side, with an outlet on both heads back to the radiator. The coolant flow route is from the radiator through the pump to the right bank of cylinders, with a passage to the left bank that runs through the lifter galley under the intake manifold. The temperature is balanced between banks through the use of a small outlet in the right bank head to the radiator, and a larger outlet in the left bank. The larger outlet on the left bank offers less resistance to flow, so that the coolant which is already heated somewhat by the right bank flows through the left bank faster. I want to insure that I have relatively similar temperatures on both sides, hence the "want" for a dual indicating gauge. I assume that the Cadillac engineers did a pretty good job of keeping the temperatures equal side-to-side, but since I am running Edmunds heads and using a two-into-one tubing manifold for the coolant return to the radiator I may well be compromising all those formulas and slide-rule calculations that were made so many years ago. I will have a thermostat in the return manifold. Originally the thermostat was in the radiator, and rather than control coolant flow it operated shutters in front of the radiator to control air flow. Thus ends todays lesson on the Cadillac flathead cooling system. Now, do any of you know in which thread this dual-needle gauge appeared, and have a link to it? I can find all manner of dual digital gauges, but I'm not going that route. Nor do I want to do the SPDT toggle switch deal to a single indicating gauge if I don't have to.
There are a lot of hamb posts on this subject. I just installed separate gauges on each head directly. Honestly, I rarely ever look at them as long as I don’t have an overheat issue. Here is the link specifically from this forum. https://www.google.com/search?q=dua...uMzguMZgBAKABAbABHg&sclient=mobile-gws-wiz-hp
There are duel temp cylinder head temp gauges . Not sure if this will work for you . There are fuel temp gauges in the market but most ate new modern stuff . smiths back in the 70’s made a duel temp / oil pressure gauge , possibly modify to suit ?
I would be looking in the areas of things that use more than one engine; tanks, boats, airplanes. The only common single gauge twin needle I can think of would be for aircraft though.
https://www.ebay.com/itm/185755562533 100°C - 212°F. Not using much of the displayed range on a water cooled application.
I was going to run two senders on my FH V8 (never did) but was going to use a switch and toggle between the two of them. I was going to do it to just keep from buying more gauges and just use the factory one in the cluster.
If his Caddy is running at 300°C, I think he's got a problem. Need a CHT from a water cooled twin, like a Diamond or something.
The Jalopy Journal
