Temp gauge not working

[70CHEVYBB]

I am trying to get my 72 in order. I have a problem with my temp gauge. PO had put in after market gauges and tied up extra wires. I found the temp gauge wire and touched it to ground and the gauge flickered. I figured it would work. I installed a sending unit and it all the way past hot. I then found out the sender was light only. I then installed one for a gauge. After warming it up it goes to the low side of the red hot mark. I do not think its the gauge because I switched out the gauge cluster from my 70 that was working. Could I have a ground issue? I did use teflon tape to seal the threads.

Thanks, Wes

[MikeyMan]

Do you have the sending unit from your 70 that worked with those gauges? If so, swap it.

There are many threads on this board about new sending units from the parts stores not working accurately with our original factory gauge. Not sure where I got my sending unit for my crate motor, but my factory gauge then read closer to the hot mark.
I don't think teflon tape is an issue, threads will cut through and you are getting a reading.

Hopefully, others will chime in where to get a sending unit that will work properly with the factory gauge.