C3 electrical water temp. gauge

[Keith McVay]

I bought a new electrical water temp. gauge for my '72, does anybody know how to calibrate the gauge without sending it off?

[Wayne W.]

Re: C3 electrical water temp. gauge

You should not have to do anythnig to it.

[Jack H.]

Originals were....

calibrated at final assy by putting them in a jig with precision controlled supply voltage to the gauge and a pre-defined precision resistor from the gauge to ground. Assembler picked from an arrayed selection of wire wound shunt resistors and installed the appropriate value resistor between the rear terminal posts of the meter.

As Wayne says, if your gauge is really 'new' then there's nothing for you to do. Any temp discrepancy you see should be double checked with a 'second opinion' thermometer (like IR gun system directed to the upper rad hose when the engine is warmed up). If she's off, it's most likely the result of your temp sender and/or your installation of it (use of too much or wrong kind like teflon tape can artificially raise sender contact to ground resistance at the block/cyl head).

[Keith McVay]

Re: Originals were....

I have a new GM sending unit, I also have a new & old electric gauge. Both are registering 210 'Degrees'. I have a manual which is registering 165 'Degrees' which seems to be right considering that the motor is not hot. Corvette Central are saying that they can re-calibrate the gauge but it takes 4 weeks, I was just trying to find a quicker way.

[Craig S.]

Re: Originals were....

Keith - there have been multiple posts on the boards about the sending units being inaccurate with the guages...I suspect that's where your problem lies. The current GM part will not give a correct temperature. I believe there is a NAPA unit that apparently will give an accurate reading...seach for posts on temp sending units....Craig

[Ed Jennings]

Re: C3 electrical water temp. gauge

You can buy a look-alike sender at Autozone for $6 that seems to work well with most vintage gauges. Ask for a Wells TU5. It is near identical to the Delco unit in appearance, but lacks the logo. If you have a digital ohm meter, a proper sender will read very close to 700 ohms at room temperature.