Water Temp Sender for V8 Conversion, To drive the original oil temp gauge Options

[DickSteinkamp]

What sender are you non P-motor guys using to use the original oil temp gauge as a water temp gauge? Mine is a Chevy V8 in a 1976 if there is a difference.

I have tried several VDO senders. The closest I can get is their 323-057

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It is their 0-150C (0-300F) sender. The problem is that it centers the needle at 75C (165F) so at normal operating temps, the needle is about midway to the right of center.

Their 0-120C sender exaggerates this even more. Their 0-200C sender centers the needle, but won't give me much warning if I start to over heat.

[Chi-town]

Use the 0-300 and send the gauge out to be recalibrated to where you want it

[914forme]

If your gauge has numbers take it out bench test it, 4 screws hold it in the back, and you can gently move the needle to where it needs to be, then retest it. Get it to where you need it to be, not to hard, it has stops on the low and the high sides.

Move the needle while the gauge is off. Be gentle, as the gauge shaft can be bent ( harder than you might think), but the needle themselves are very light gauge metal, can be mangled with ease if not careful.

It is also a good time to repaint the needed if they are sun faded.

[DickSteinkamp]

My gauge doesn't have numbers...

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...but that wouldn't stop me from centering the needle at about 200F. The problem with that is I would probably destroy the gauge. (IMG:style_emoticons/default/sad.gif)

The three VDO sending units I've tried seem to be linear but start at 0. I believe the original sending unit for oil temp was probably something like 60-160C (140-320F) with about 110C (230F) as the mid point. The engine would normally run just under the mid point.

I'd love to end up with something similar. Maybe something like 130-270F with 200F as the midpoint.

I've considered using the stock oil temp sending unit (it would probably be close enough), but I think it might be tough to adapt the metric threads on the sender to the NPT threads on my intake. Has anyone done this?

Chi-town...do you know of anyone who recalibrates gauges?

[Chris914n6]

Cook the senders at 212f, measure the ohms to find the difference, then add a resister to get close to centered on the gauge.

[DickSteinkamp]

Cook the senders at 212f, measure the ohms to find the difference, then add a resister to get close to centered on the gauge.

Good idea! Thanks!!...but maybe instead of trying to figure out what resistor would do the trick, put a potentiometer in line between the gauge and sending unit and center the needle using the potentiometer when the engine is at operating temp. Does that sound like the same sort of thing?

[Chi-town]

North Hollywood speedometer
Seattle speedometer
Palo Alto speedometer

[DickSteinkamp]

In retrospec, I don't think the resistor/potentiometer thing is going to work. That resistance will be there full scale which will prevent the top end of the needle movement from happening.

Thanks Chi-town. I've done a lot of work with Seattle Speedo, but since they (he?) moved to the Spokane area, not the same results. I'll try one of the other two.