Dual needle temp gauge.. Does it exist?

Hi. I have a friend building a merc with a flathead, the client wants a temp sending unit on each bank. The stock instrument cluster has room for 4 gauges, and he doesn't want to modify it or run an additional temp gauge below the dash, etc..

Sooo... A temp gauge with 2 pointers, one for each sending unit would be the answer. Does anything like this exist? I don't think I've ver seen one. They have these type of gauges for air bag setups, so maybe one for temp isn't that far fetched? Thanks fellas.

 

Maybe I've dreamt it, but I could swear I've seen one. I'll dig through my Flatmotor catalogs and see what I can find.

 

Here's a dual oil pressure/water temp gauge:



I found it here: http://www.gaugeguys.com/Smiths/classic.htm There are probably others, it's just the first one I found with a google search.

It's not exactly what you're looking for but it would get two gauges in one hole. I do recall seeing a dual temp gauge somewhere.

Edit: here's a dual cylinder head temp gauge:



http://www.ecas2cvparts.co.uk/cylin...ius-diam-includes-fitting-details-p-1516.html

 

He wants one with 2 temp gauges on it, I believe.

 

That's nothing like what he asked for. I've personally never seen one but who knows.

 

Maybe you could get two gauges and combine them so they share the same housing?

 

He could run a switch, and flip for other side, unless he wants to monitor temp all the time. Trucks running exhaust pyros often do that rather than spring for 2 gauges. If not he should contact Instrument Sales and Service in Portland,Or and see if they carry one. They build gauges for many different applications and if anyone builds a dual gauge they will know about it or maybe even build it themselves.

 

Westach makes them, I have one.

http://www.westach.com/

 

Maybe check what aircraft are useing. Seems to me i've seen that in a cockpit once.

 

Wow, awesome guys, thank you. Were really just trying to fit 5 gauges in 4 holes, and looking for the best way to do it. The switch idea isn't bad either, but the client wants to keep an eye on both at once all the way down the road. Thanks again fellas.

 

That's where I saw it! Smiths!!

 

Check out Classic Instruments.

Link

 

Ive heard of people running them with a toggle switch, switch back and forth, But a 3 way toggle might work better, Rt, Both, and Left

 

Hook up a blinker relay and have it constantly flip back and forth between the two senders. The sound would drive anyone nuts though.

 

And how exactly would "both" work?

 

Voltage-wise it would read double. Resistance is halved when resistors (senders) are in parallel, so half the resistance would flow twice the voltage. Whether or not the voltage-to-gauge-scale is linear and it would actually read twice the temp on the gauge face is another story.

Worst case you'd get used to seeing a normal range on the 'both' setting, and could dial it down to one side or the other to diagnose it if it got too high.

Edit:

I was wrong, it's a little more complicated than that. The half thing works when it's the same resistance on both, but if they're different it gets a little weird as they get farther apart:

R = total resistance
R1 = first resistor (sender)
R2 = second resistor

R = (R1 × R2) / (R1 + R2)

If they both read 20 ohms, the combination would read as 10. If one read 30 ohms and the other read 10 ohms, the combination would read as 7.5 ohms.

 

Westach makes dual water temp gauges in 2", 2 1/4 SQ, and 3".

 

I said "might", I'm sure there is some way to wire it, stock flatheads ran both after all

 

Westach will make you just about any combination of gages you can think of. That's why people keep saying Westach makes them. They do.

 

Jkustom,
If your freind is running the stock gauge and sending units. The best way to read both heads is to install a single post sender in each head and wire them through a switch to the gauge.
Shaggy,
Ford used two different sending units on flatheads. The single post unit is a true temp sensor. The two post is a simple over temp switch. The wireing runs from the gauge to a terminal on the two post unit(left bank), then from the other terminal to the sensing unit(right bank). The switch unit opens at about 210°F. The Ford sensors are not resistive. They use a heater coil wrapped around a bi-metalic strip to open and close contacts. The rate that they open and close control the position of the gauge pointer. When the two post switch opens in over temp the gauge goes hot, same as when the ignition is off.

 

i haven't done it yet, but i thought you could get 1 electric gauge, and 2 sending units, 1 for each side of the engine...then use a toggle switch underneath the dash to switch from each side of the engine...this idea would work...no?

 

We have looked at this, very doable in a 3-3/8 size, but just too tight in a 2-1/16"
We have a couple of alternatives which use a single gauge:
1: dual senders: 2 senders and a toggle, pretty easy
2: dual senders 2: We have senders which are half the resistance, so you can run both to one gauge ahd have an average of the temps of each head. Similar to installing a sender in an intake manifold on other water cooled engines.
3: Sender with warning. We can use a standard sender on one side of the engine, and a warning sender on the other. Basically, the gauge acts normally until the warning sender triggers at a pre-determined temperature, this will peg the gauge.-Probably the easiest option and then you know which side has the problem.

Brought this up a while ago but was dismissed for "why don't you just produce a dual temperature 2-1/16 gauge" We looked at is, but just can't make a business case for it, investment is just too high and volume too low. The killer is the small custom movements and circuit drivers, need alot of development which equals $$$ up front.

Mark

 

Thank you, Mark.

 

The Westach ones I see are square. Anything that looks more appropriate? Stewart-Warnerish?

 

With my flathead, I think I'd rather run two temp gauges and give up the oil pressure gauge, using an oil light instead.

 

this is getting way to complicated. What is wrong with stock? put in a sender on both banks, the gauge will read the average of both. That's all that really matters anyways, Right?

 

I guess that is how my 53 Merc works, except with the ignition off, the temp gauge goes to C. My Merc gauge goes H when the engine gets really hot because of the fuel system running lean. But the right hand head sensor must not be working since the gauge never moves up during normal operating temps.

 

The top gauge won't work as that gauge is mechanical for both sections. The temp gauge has the borden tube, whereas the oil pressure section is just a tube going to an oil pressure port on the engine.

 

There are ways of making a single electric gauge work for sensing both heads. A simple circuit can be built to take both sender units and electronically switch their signals at a reasonable 30 second rate to the gauge. LED's could indicate left or right bank reading and could be placed in or near the gauge.

I will probably build one up for my 53 Merc, but first need to characterize the gauge operating properties.

 

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