Sixties era V-8's: Do you prefer 160 or 180 degree thermostat?

[JamesR]

I replaced the water pump in my Mercury FE engine. I though it might be a good time to try a 180 degree thermostat, which is what the car originally came with. I had put a 160 degree thermostat in a few years ago and it made the car run a little cooler with in town stop and go traffic. It turns out though that I mostly drive the car on the highway now. With the 160 t-stat the temp gauge read pretty consistently 165 to 170 on the highway. It's a mechanical gauge so when the car was turned off the heat soak would get the gauge up to over 200...maybe 210 or something.

 

After installing the 180 t-stat the other day I drove the car my usual 25 miles on the highway and the gauge read consistently 185-187 degrees. When I returned I worked on something and left the engine running in park. The temp got up to over 200. I shut the engine off and the heat soak got the temp up to 220. Only time I've driven it with that t-stat.

 

What temp do you guys like with your sixties era V-8's? I drive ONLY in the spring-summer-fall and mostly on the highway. They do make a 195 t-stat, too. Thanks. 

[Jubilee]

For me, if it has a direct drive fan, it gets a 180. Fan clutch gets a 160. I like a direct drive fan on anything that goes in a parade.

[EmTee]

It sounds like your radiator is doing its job.  The thermostat essentially establishes the minimum coolant temperature.  180° was the norm for most cars in the '60s and early 70's.  The exception was A/C equipped cars, which usually called for 195° thermostat.

[Rusty_OToole]

If the cooling system is in good shape and will stand at least a 7 pound pressure cap the 180 would be best. Better fuel economy and more heat from the heater. If the cooling system or heater core are iffy, a low pressure cap and low temp T stat might be safer.

[30DodgePanel]

My 68 Chevy truck has a 327 and I've sampled both and prefer the 160 due to a few factors.

 

Since a 327 run hot naturally and because I'm in the desert I use the 160 and it definitely helps stabilize it where I feel it's safer on the engine and can still pass emissions testing annually, even though specs call for the 180. I also have a TH400, so the lack of overdrive contributes to my decision. Keeping the carb dialed in is key also and that's the tricky part for me since it has the original Rochester on it and as we all know, they are finicky.... 

 

I have a 4 core radiator and vintageair kit a/c btw. 
The cooler the better in this heat.

I suppose if I was in a cooler climate I'd use a 180 though.

Edited August 13, 2023 by 30DodgePanel (see edit history)

[John348]

I don't really drive my cars all that much but when I do I like to keep things cool. Everything was new when they were restored and the blocks were bored so, living by the quote "cooler heads prevail" I like to use a 160 degree stat and I use the Robert Shaw high flow thermostats in all of them.

Plus we are not running the same quality fuel that was used in the 1960's, which I was told is a leaner, and hotter mixture. I had used a 180 stat and things got a little touchy in traffic. Once I advanced the timing a little and went to a 160 stat things were a little less nerve rattling. Not a good feeling leaving the show field at Hershey and watching the gauge climb

  

[JamesR]

4 hours ago, EmTee said:

It sounds like your radiator is doing its job. 

I plan on eventually having the original radiator re-cored, but in the meantime (until I can find someone I trust to do the job) I've replaced the original with a good quality aluminum radiator from Wizard Cooling. I put it in a few years ago and it works very well. Not cheap, but worth it for the quality. The fact that Wizard actually makes a unit that fits early '60's full sized Mercuries was part of the reason I went with them, too.

 

Quote

180° was the norm for most cars in the '60s and early 70's.  The exception was A/C equipped cars, which usually called for 195° thermostat.

Was the 195 t-stat on A/C cars to get better performance with the defogger function? I can't think of any other reason. But maybe they didn't even have a defogger on early A/C units (??)

Edited August 13, 2023 by JamesR (see edit history)

[Pfeil]

190 for me, on my 60's water cooled cars. Early 70's cars (1971-1974) those were the years we were trying to EPA certify cars for emissions. Those pre catalyst years were difficult because we were trying to do everything on just the engines so everything was about thermal efficiency or maybe just beyond. Many G.M. cars of that era had 205-degree thermostats. My 1976 Olds, with catalyst, per factory uses a 190-degree thermostat.

The image below is from Phil Andrews on the Pontiac section of the forum, 1951 Pontiac Chieftain. Today we would be looking a normal range. In fact, if you had a GM product that had idiot lights from the late 50's to mid 60+ you would never know your temps were this high. 1959-1970 Pontiac hot temp light comes on at 246 degrees.