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OK, my fuel gauge works fine now but a newly purchased (NOS) temperature gauge and sender was returned from Joe Ray's Parts after calibration but calibration is way off! Room temp = 140F and running temp = 240F. Calibrating a temp gauge along with a sender can't be rocket science. Joe Ray says that he uses boing water, pulls the needle off and sets it to 212F. Is there any tricks to pulling the needle off? I don't want to ruin a $130 gauge.
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Re: 1963 Temperature Gauge Diagnostics
Sender may be a newer one that always reads high, C1's have that problem if store bought, but some dealers say they have the right repro ones. -
Re: 1963 Temperature Gauge Diagnostics
I for got the grounding of the sender may be off!Comment
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Re: 1963 Temperature Gauge Diagnostics
Original gauges from the era of your car were factory calibrated using a special test fixture. The fixture emulated the voltage + current conditions to simulate the engine just going into overheat. The assy worker installed the needle pointer onto the gauge's shaft pointing into the low end of the red zone and that was that.
They didn't much care about guage accuracy under 'normal' driving conditions (is 180F really 180F on the gauge?) as the purpose of the temp gauge was to show general engine heating trends and be accurate in warning of a bona fide overheat threat. Today, we're used to modern systems that are accurate across their entire dynamic range and we tend to INSIST our classic cars operate similarly with a high degree of mid-range accuracy...
If you attempt to re-calibate your gauge with your actual temp sender using the boiling water approach, you'll be 'close' so long as you do NOT stumble on the common pitfalls of this approach:
(1) The temp sender must be immersed in the water and NOT make physical contact with the container (you don't want temp to climb above 212F due to a heat conduction path separate from the boiling water.
(2) You need to wait long enough for the temp sender to come up to temp and equalize its temperature with that of the boiling water.
(3) Use the right power source for your calibration circuit. When the system is installed in the car and on the highway, the source voltage is NOT 12 VDC! In actual use, the car's generator/alternator is active and is pumping the battery ABOVE it's normal 'rest' voltage to keep 'er charged. You want a source voltage of approximately 14.2 VDC and not 12.0 VDC, otherwise you will mis-calibrate things...Comment
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