I am also curious if others with upgraded and modified V8s are seeing their stock temp gauge read high as well.

We discovered something interesting today. We took some values of resistance in boiling water and different temperatures with the sending unit. We then duplicated them with a POT and got the gauge to read somewhat normal. When the car is running it reads higher than this. Why would it read high with the car running? Interference from something?

I am wondering if it has anything to do with the aftermarket 100 amp alternator, or maybe the fact that the coil is mounted right next to the sending unit.

Does anyone think it is the voltage regulator on the back of the cluster that is causing this?

 

We discovered something interesting today. We took some values of resistance in boiling water and different temperatures with the sending unit. We then duplicated them with a POT and got the gauge to read somewhat normal. When the car is running it reads higher than this. Why would it read high with the car running? Interference from something?

 

This is the advantage of a mechanical gage.

 

We discovered that the instrument panel voltage regulator is the culprit.

The new one I had was erratic.

I reinstalled my old one and the gauges read a little low.

I have been through several of them and none of the replacement ones are worth a damn.

I am making an electronic one.

 

BTW I have observed that a return spring from the carb attached to the sendind unit that is touching metal will give a false reading