Took my '84 351W/4bbl/AC/Auto on a 75 mile trip yesterday..Most of the time the truck never goes over 10 miles or so. It took all that way for the temp. gauge to get off the marks..BEFORE the NORMAL starts.. I know there are a couple reasons why..SO..I think the thermostat is a 160..so I'll change it to a good 180 or 195.. I see both mentioned here.....That being said..Which Temperature 180 or 195...???..and should I install a new sending unit while I'm at it ?...thanks..J

 

OE is 192, so 192 or 195

 

The 192/195 range is a bit better for MPG and winter heat, while the 180 is a bit better for all around use including hot summers with the A/C running.

If the temp gauge stayed below the "Normal" zone for most of that trip, I'd suspect the current t-stat is stuck open. Of course, I have also seen this same symptom from a t-stat installed backwards, though that usually results in the engine overheating.

 

The sending unit for the gauge could be bad...but honestly, these gauges aren't exactly accurate anyway. :\ With a new sending unit, mine would tell me I was overheating when I was at 210F...

Personally, I use Autometer gauges for water and volts (eventually gonna get oil pressure). I get actual numerical readings instead of having to guess.

 

I have only driven the truck 1800 miles in the past 4 years..None in the winter...It has 109K on it. I will get a GOOD 180 thermostat..and probably replace the sending unit while I'm at it. Miserable job..but did it a lot of times when we used to build Replica Cobras and GT 40s. Not one of FORDS better designs...J..

 

I use whatever is factory.