temp gauge

[scooby3242]

Newbie here!!! I have found alot of post about the temp gauge, but haven't seen this problem. My 71 c10 had after market gauges when I bought it and changed it back to the original gauges...Well all the gauges work except the temp gauge...when you turn on the ignition it pegs hot...my sending unit and engine harness are new...so i thought it was the resistor on the back of the guage. I had another one that was on the back of another fuel gauge I had... same results..pegged hot... so I had a brain fart and noticed that the nuts that I put on the temp gauge to hold down the resistor were different(looks like zinc plated nuts) so I took the nuts that were on the fuel gauge and put them on the temp gauge and the gauge did not peg hot anymore. My question now is does the nuts make that big of a deal? and the temp gauge only goes up about a quarter of the way....I have a 350 motor with a 180 thermosat.....How high should the temp gauge go with a 180 thermostat? thx for the replies.........................