FLATHEAD TEMP SENDING UNITS
- Thread starter 34ford
- Start date
slim
Well-Known Member
If you run bouth sending units back to the gauge-parralle it should read the hotter of the 2 sides if i remember right higher ohm reading = cooler temp so gauge should register the path of least resistance or hotter of the two simple enough to hook up and test to make sure im not full of .... Two gauges would be the ideal setup but in sure you already considerd that.
34ford
Well-Known Member
Slim
;That would work somewhat but not well because the gauge would not match the sending units .If you put for example two sending units in parallel and they were 150ohms each the total would be 75ohms The would cause the gauge to go quite a bit left or right depending whether they were positive or negative coefficient.The original sending units for the original gauges ,one had a single contact to ground and the other side had 2 contacts isolated from ground and they were wired in series to the gauge. They were matched to the gauge. If either one got hot or cold the gauge would move only because they were calibrated that way. Unfortunately modern gauges are designed for a single sending unit . Now if they offered the same sending units done the same way as the early style that matched the new style gauges then that would work but on checking they don't .I guess the demand it too low for all of the gauge manufacturers .There are about 6 different values . Thus back to a switching device .This will solve the problem for all manufacturers . For now I used a dual contact flasher which is doing the job but noisy.
Bob
;That would work somewhat but not well because the gauge would not match the sending units .If you put for example two sending units in parallel and they were 150ohms each the total would be 75ohms The would cause the gauge to go quite a bit left or right depending whether they were positive or negative coefficient.The original sending units for the original gauges ,one had a single contact to ground and the other side had 2 contacts isolated from ground and they were wired in series to the gauge. They were matched to the gauge. If either one got hot or cold the gauge would move only because they were calibrated that way. Unfortunately modern gauges are designed for a single sending unit . Now if they offered the same sending units done the same way as the early style that matched the new style gauges then that would work but on checking they don't .I guess the demand it too low for all of the gauge manufacturers .There are about 6 different values . Thus back to a switching device .This will solve the problem for all manufacturers . For now I used a dual contact flasher which is doing the job but noisy.Bob
slim
Well-Known Member
have alook at the koyo unit 10-30vdc programable ya your right on parrell 75 ohm series 300 simple relay is no problem but timer to trigger it whithout making all sorts of racket is the pain http://www.automationdirect.com/adc/Overview/Catalog/Relays_-z-_Timers/Timer_Relays
I run two gauges on my flathead, with a sending unit in each head. It works very well. In fact, the thermostat on the right head seems to stick till it gets to 200 degrees, when it initially warms up, then opens, then runs right back down to normal again. The right side always runs 5 degrees hotter than the left side as well. I find it very interesting to watch the two gauges. Glad I did it that way, on a motor that is supposedly notorious for overheating.
Digger_Dave
Well-Known Member
Flat head Temp Gauges
Bob, like others have said, using TWO gauges - and two sending units, or a switch for left and right sending units is one way.
But as noted, the right bank is the one I like to keep an eye on. (it tends to react to rising temp changes faster)
Ford's sending units shared the signal as well as being 6 volt.
But I think you can keep it simple with only one sender - for the modern gauge - on the right bank and plug the left opening.
Before I make an electronic switching unit to handle dual sending units for modern gauges
Maybe Dave knows ?
Bob
Bob, like others have said, using TWO gauges - and two sending units, or a switch for left and right sending units is one way.
But as noted, the right bank is the one I like to keep an eye on. (it tends to react to rising temp changes faster)
Ford's sending units shared the signal as well as being 6 volt.
But I think you can keep it simple with only one sender - for the modern gauge - on the right bank and plug the left opening.
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Ford gauges didn't really "share the signal"....The right one was a regular style sender that worked the meter, the other was like an idiot light that broke ground at a predetermined temp and put the gauge all the way to "Hot". That's why the gauge works backwards to most, so a no-ground causes a hot reading.
