Update on the temp problem.  I changed out the IVR with a new solid state one from Mac's and saw a dramatic change.  It now only reads midway when at a temp of 180.  The fuel gauge reads a little lower but I can deal with that.  I can possibly adjust the float a bit or try a different sending unit.  But at least I can now trust the temp gauge.

Now onto the next issue.

Thanks all for your suggestions.  

I'm not certain exactly what type of dash gauge indicators you're discussing but there are calibration adjustments possible on some of the Ford gauges. It looks like the old game of "Operation", lay off the caffeine for a day or two, but it's worth investigating.

On my '56 Third 312, I replaced my temperature sending unit with a reproduction unit. The gauge then read high even though my infra-red temp sensor showed normal temperatures. I found and installed a NOS sending unit and the gauge read correctly.
Jim  Yergin

hi just a thought but does the guage or the dash unit need to be earthed properly??i had this fault with my fuel guage good luck

Thanks for the input and suggestions everyone.  You have given me a lot to consider and check.  I find it hard to believe that the IR thermometer could be reading 40+ degrees off.  I do have a second one at work I could compare it to.  I have to believe it's either a sending unit or a wiring issue.  Fortunately I do have two of these cars.  A coupe and a convertible.  The convertible is the one with the problem.  The coupe on even the hottest days runs mid range on the gauge so I have been using it for comparison.  Over the weekend I'll run some tests and keep everyone apprised of what I find.

Sure sounds like the problem may be the sender. I'm assuming with engine running cold, gauge is indicating cold. Then at some higher temp, the gauge works its way to indicate hot. At this point with engine running, pull the connector from the sender and see if the gauge returns to cold. I know you replaced the sender but more than once, 2 defective parts were on hand. I don't know if the Lincoln car uses the same system as in the Ford. There is a procedure in the 57 Ford book using two 1 1/2V batteries in series to test the gauge. It (3V at the gauge terminal with the key off) should put the gauge aprox. 1/2 scale.  I remember an analog volt meter will show a pulsing needle that should average about 5V at the disconnected sensor lead.  I know you said the other gauges are working correctly but that doesn't mean there isn't an issue with the temp circuit. Check the Lincoln manual for the correct procedure as this may not apply to you. Hope this helps, JEFF>..........


64F100 57FAIRLANE500

I don't have a lot of faith in IV thermometers. From my experience when doing aircons they did not give accurate readings on all surfaces. This clearly showed up when trying to get a reading off copper pipe. The readings would very greatly depending on which way you held your tongue. The only accurate way was with a touch probe thermometer.

This is a question-are those gauges King Seeley (?sp) like the Ford gauges of some years?

I use an aluminum based anti seize on electrical sensors, or the copper coat electrical compound.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

This is a long shot.. I have read (but never experienced)  that putting to much sealer on the threads of the sender can disrupt the path to ground and cause gauge inaccuracy..  But then on reflection I would guess that would cause the gauge to read low  not high..

Put a volt meter on the feed to the temp sensor and see what it says.. It should read the same for all the sensors,oil pressure and fuel gauge as well.
I once had a Stewart Warner gauge that always read at least 20 degrees high on temp.. I finally started putting resistors in line between the sender and the gauge, till the gauge reading matched the IR reading.. PITA but it worked..