I run a 180 degree thermostat. As I remember, that is stock. With a 15# pressure cap and 50/50 coolant, the boiling point is around 250 degrees. Lower temperatures may accelerate wear. You could possibly go a little higher. Not sure, so let's see what others say.

 

Oh no, you've re-opened the can of worms! There's some guy who will go nuts here arguing that your engine can't get too hot (or some such stuff!) LOL
Stan

 

Bingo.

 

Stock was a 192 degree thermostat.

 

So the range is 180 to say 240? Anything higher is overheating or is 240 even too high?

 

240 is pushing it. Can we agree on 180-195? Anyone?

 

Just remember the thermostat temperature just calls out what it opens at...coolant temps run higher than that. A 180-195F tstat is plenty.

 

OK let me ask this another way. At what temp should I shut down to prevent overheating?

 

240 and climbing ... Shut 'er down!

 

I get uncomfortable at 220.

 

seems hot to me

I have been fighting temp problem for a long time on my 67 pony. It runs at around 220. Seems high to me. The dash gage is almost pegged. Have changed fan clutch, thermostat, head gaskets and got radiator "rodded" also added an electric fan. nothing helped. have ran out of ideas.
any ideas would be appreciated.

 

I'm new here and came here with the same question of what is a normal operating temperature? I always remember 210 as a running temperature and will check my truck tomorrow for a temperature comparison. Mine goes one step further as with this new rad and e fan I was hoping for better results but I hit 200 this weekend with a 90 degree day and local driving and my issues is I vapor lock the mechanical fuel pump set up. Has happened 2 times now. I read a online article that to trouble shoot your system do a temperature gun and compare lower and upper radiator hose temps. Should be close or you might have a blockage in the block. Have tried this yet. The article also mentioned hot temps on frwy driving is a low coolant flow issue. High Temps local is a airflow issue. The specs on my e fan is "suppose" to be 1700 CFM and at the local O'Reilly's. The have a 2200 CFM fan available. So debating going back to mechanical fan with shroud. Sorry just rambling. But feel some good info. 🤔

 

180-195

 

I Googled "What is the optimal operating temperature of a gasoline engine" (even though I already knew) and it came back with as the first result:
"195 to 220 degrees Fahrenheit
For most cars, the normal operating engine temperature is in a range of 195 to 220 degrees Fahrenheit,..."

Which I have found to be true myself, but I'm just some guy on the internet. The fact that the factory originally specified a 192F-195F thermostat I always took to mean that Ford did not intend for my Mustang to BEGIN to start needing to cool itself through the radiator until it reached at least that temperature. So I imagine they knew all about the 195-220F thing even back in the 1960's.

 

I agree with Gypsy, given the fact the original stock tstat didn’t even begin opening until 192.

The next question is how are you determining your current temps? I would not rely on the original stock gauge and wiring. You should use a mechanical temperature gauge to verify accuracy.

 

I have a mechanical temp gauge in the upper radiator hose and agree, one is required to a more accurate number.

If any one has an electrical fan model they have would appreciate a share. I am on the path now to go back to mechanical as have a shroud ordered and have my original fan still.

 

Unless buying at the high end, most electrical gauges are only 180 degrees sweep, or less. while most mechanical gauges are 270 degree sweep or more. This makes the mechanical gauges easier to read and easier to pinpoint the displayed temperature quickly and get your eyes and attention back on the road in front of you.

Check out the autometer gauge line, they are about the best gauge one can buy for a reasonable price.
This is the one I’ve used on several vintage Mustangs and Shelbys.

https://autosalesinc.pxf.io/c/40473...39/2996090/35994?subid=autolinker&u=https://www.summitracing.com/parts/atm-2421

I’ve never had any trouble with their nylon connecting line over many many years. But if one has concerns about the reliability and / or safety, Autometer sells a braided steel line which should be bulletproof.

if I was go with an electric oil pressure gauge, I’d definitely get this one:

https://autosalesinc.pxf.io/c/40473...39/2996090/35994?subid=autolinker&u=https://www.summitracing.com/parts/atm-5652

At $235.00 It is more than double the price of the AutoMeter mechanical oil pressure gauge, but it’s a full 270 degree sweep gauge with a more accurate sending unit than the other (cheaper) electric gauges which are less than 180 degrees sweep.

Z

 

Old, but still VERY relevant and helpful thread,.......

 

I thought old posts were to be deleted.....

John

 

Very relevant all these Many years later,.......

 

 

On small block Ford's if you take the valve cover off and there is sludged oil on the heads it's running too cold, crusty oil means it's running too hot. Engine blocks are designed for a specific temperature due to the cylinder wall thickness from the factory, that's why some engines that are over bored with stock cooling systems will over heat

 

@zray - I aborted my electric fan - ebay cheapo - came with a 3 core radiator (keeping it) and they gave me a refund for $45 towards the fan not working. Shows you the value of it. LOL......

My Gauge set-up........
Bosch SP0F000053 - 2" mechanical temperature gauge - 100-250F ($25) amazon
Autometer 2283 - 1-1/2" radiator hose adapter with gauge tap for mechanical gauge. ($50) walmart
Installed and working great.

Yet to be installed.....
Replacing existing clutch fan and fan blade (fan had both 16" and 17" blades) not sure why different sizes.
Part# FANS11 - 4" deep plastic shroud (up to 17" fan) - ($80) CJ PONY
Derale 17015 15" heavy duty stainless steel flex fan ($80) amazon (chose 15" for extra clearance)
Derale 34550 2.5" fan spacer ($25) amazon (size will vary based on fan blade and motor accessories)

Will update once installed and see how the temperatures go.