As per above, when you incline, the needles swing freely. I would like to test each gauge electrically, from Zero to Top (tach, speedo, temp, press, amps, etc.), with a 12V battery and hit the +/- ? The speedo, no issues, w. the old drill. I want to be certain before I install. Thank you. Regards, Alberto
I think I'd go with something that has a little less amperage. Although some little voice in my head tells me that might not be wise either. Might be better off using a power pack for model railroading where there's a rheostat that allows you to regulate the voltage, from zero to 16 volts and the amperage is low. I might also put a voltmeter inline to watch exactly how much voltage I was feeding in. The tach if fed pulses at a constant voltage, not variable voltage, right? So that's not going to be all that easy to do. Or, pack them up and send them to Palo Alto Speedo for testing. http://www.paspeedo.com/ Personally, that's what I'd do. D
I think the temp gauge reading at least is resistance dependent, which means you’ll need a variable resistor box to dial up the right resistance for the right needle position. And it’s probably nonlinear, which makes it trickier. Good thing I can walk to Palo Alto speedo from my house .
Alberto, my advice would be to get a specialist company to calibrate them, especially the speedo and rev counter. The Rev counter has a electronic box and more often these are defective. You can possibly check the smaller gauges work ie needle moves but accuracy of the gauge is much more difficult to achieve. If you do send them away, then include the sender units so they can measure them all together. The veglia sender units are non linear and virtually impossible to find any real data, you are at risk of blowing critical bits in them. Tony
My problem is huge lack of accessibility to a diagnostic location, as would have to take all to the USA. Guess I can do it, but a major pain... Thanks for the great opinions, Yikes... Regards, Alberto
I sent my gauges by post to a company in the UK many years ago and then it dawned on me had the parcel been lost in transit I would have been screwed. Telephoned the company repeatedly untill they confirmed it had arrived, I then drove 300 miles to collect them when ready............feel your pain but there is no easy solution. Deliver and collect.....if you can.
Alberto, My opinion: Don’t send them out. No need to, unless you have had specific problems with them. You already know how to test the speedometer. Only the tachometer is a bit tricky to test. The rest is easy. The small instruments, that is the fuel tank gauge, oil pressure, oil temperature and water temperature gauges, are very simple to test. (Tricky to calibrate, but simple to test for function.) They are all just reading resistance to ground, and they happen to be calibrated to read middle of the scale at around 100 ohms. The sensors usually work in the range of 300 to 0 ohms to produce the readings. To test them, pull the wire going to the sensor/sender. Connect the wire through a 100 ohm resistor to ground. Turn on the ignition. If the needle swings to about halfway up on the scale, the instrument is functioning. And you are done! Better yet, use a potentiometer of around 500 ohms (1 K will do in emergency) in place of the resistor. Turn it until the meter needle points to the center line mark on the scale, then read the resistance value. They should be in the 100 to 150 ohms range approx. I give the values from my car as a reference only: Fuel gauge, mid-point (1/2 tank) reading: 110 ohms Water temperature, mid-point (90 degs. C): 158 ohms Oil temperature, mid-point (100 degs. C): 110 ohms Oil pressure, mid-point (60): 105 ohms Turning the potentiometer through, say 500 to 0 ohms, you can verify that the needle moves smoothly throughout the entire scale. And you are done the scientific way! You are now also able to check if the senders in your car are in the correct range! The ammeter can of course be checked the normal way, by connecting another meter in series and varying the load - or a bench power supply voltage. Then compare the readings. As mentioned, the only tricky item is the tachometer. It reads the frequency of pulses fed to it from the ignition. It could be tested by a simple pulse generator, but if you don’t want to go that way, you can just connect it to the Dinoplex/Winterburn/whatever ignition system you have for the car. Those systems all have a separate output feeding a clean pulse to the tachometer. To trigger the ignition, rig up any old distributor you have, and spin it with an electric motor. Those are just some ideas, you can probably come up with other, even easier ways to do the testing. But it is not, as the saying goes, rocket science. Best, Lars
Thanks for providing that link, Tony. It definitely belongs to the subject. In fact, that was the thread I was thinking of when I said that calibrating the instruments exactly may take some doing, but verifying basic operation is fairly straightforward. / Lars
Yes, its easy to check if the speedo + small gauges work but the Rev Counter is more challenging without the right equipment. when i sent mine away for checking / repair they came back like new as they dismantled the front and cleaned 40 years of grime from the clock faces as well. For me water and oil press accuracy is important.
Could I ask if you have the details of the company in the UK as I'm UK based as my speedometer over reads by 10% which then makes the tachometer 10% more mileage than I'm actually doing. Thanks for the help if you're able to provide it. Anthony.
Anthony, these are the best guys to go to. Not the fastest as they are normally very busy. Ring before you send https://www.speedycables.com/
