160 vs 180 thermostat

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CurtDawg510

CurtDawg510

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Location
Hayward, ca
So i got my 6.4 in my 70 duster.... dam thing is a runner!
Only thing i didnt like much was the temps with the 180 thermostat.... on a 95deg day it would run 192-194 deg on the highway.... fans turn on and 196, and i fell thats warm enough.... i know they can run hotter and do, but i dont like over 200 myself....
Fans would turn on almost as soon as you stop, and would cycle on and off kinda quick (one min on, one min off or so) in city drivin....
So now i am runnin a 160 thermostat, i like this alot better.... same 95deg day down the highway, im runnin 175.... and i can pull off the highway and do city drivin, pretty much all stop n go and the fans hardly turn on.... sometimes i can jump from highway to town, then back to highway and fans wont even turn on at all!... and when fans do turn on at 196, now it cools down to about 180-185 quick, then takes much longer before then turn on again.....where the 180 thermostat would keep temps right around 190-194, so the fans are almost always on....

I also have a 180 oil thermostat, so oil temps are always around 175 cold days to 190 hot days

just my experience

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You have it now so that when the t-stat opens it never closes. They are supposed to cycle. Your mileage will likely suffer. Computerized engines are designed to run "whatever" thermostat they are listed to have. Differing from that can have poor driveability results. Lastly, if the engine does not get up to proper operating temp, you'll never get all of the contaminants out of the oil. Don't take my word for it. Look up something with a 6.4 in it and see what temp the fan kicks on. A lot of them kick on at 220 even 235. They are designed to run that hot.
 
RustyRatRod said:
You have it now so that when the t-stat opens it never closes. They are supposed to cycle. Your mileage will likely suffer. Computerized engines are designed to run "whatever" thermostat they are listed to have. Differing from that can have poor driveability results. Lastly, if the engine does not get up to proper operating temp, you'll never get all of the contaminants out of the oil. Don't take my word for it. Look up something with a 6.4 in it and see what temp the fan kicks on. A lot of them kick on at 220 even 235. They are designed to run that hot.
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But they pull timing when air intake temp reaches 117-120 deg, and or coolant temp hits 240.....im also tuning it with HP tuners, so its not really designed to run that hot anymore, i know they run them that hot to burn cleaner for emissions.....i drive in some heat, i dont want it runnin 20-40 deg hotter than thermostat rating when runnin down the highway....isnt that more when thermostat is stayin open?
And for the oil, i runnin an oil thermostat, that keeps oil temps up....
I get average 20mpg.... hot doggin included
 
I agree with everything that RRR has to say, componets have a tendency to wear out sooner as well when they're not operating at the designed temps.

That being said, you've got to be comfortable with the car as you're driving around town. I hate the feeling of having to keep one eye on the temp gauge and the other on the slow moving traffic ahead. I think part of the problem is that you may have poor air circulation within the engine compartment. Dropping in that behemoth has reduced some of the effective area that would allow for airflow and dump some of that engine heat.

I once had a 30' 5 window coupe with a big *** engine in it that was tightly cowled and had the same problem as you. I tried a lower rated t-stat which helped, but eventually took the cowl side panels off and that solved my problem. Dump the engine heat in a tightly cowled engine will help the cause, especially in stop and go traffic. Hot rodders would cut louvers in the hood to help facilitate the problem, but I wouldn't expect you to do that.

I'd run it as is, you can always swap in another t-stat if need be.

Great looking project! I'd love to see the whole car.

95* in Hayward? Eww!
 
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Very nice project, but I would have to agree with Tinmannz about the motor being boxed in. It appears to be very snug in there. Are those scoops functional?
 
You may have a bad thermostat, or something wrong with the cooling system OR a faulty gauge. But putting a colder stat in is not the answer
 
Sounds to me like you have it set up nicely.
Great looking car.
 
Engines are designed to run in a specific temp range. As the engine heats up all the metal expands, the gaps designed in are there for that temp range, a lower temp range tightens up those gaps for better or worse.

I agree that modern engines are designed to run hot for emission reasons, and that might be hotter than is good but the modern engines seem to last 2 to 3 times as long as our 60's engines so they must be doing something right. I would go with what the factory used.
 
If it's no longer tuned "stock" ....who cares.

They stat runs open, partially or full. They open before the rating as well, the rating means 'fully open by 160'
Run the temp where the tuner manual recommends ..because it's usually so the tune doesnt cause engine damage

Enjoy.
 
Changing the tune doesn't change how the engine is machined. Youre going to wear things out much faster.
 
A good stat sets the minimum operating temp.
The efficiency of the rest of the system sets the maximum. The efficiency is always changing, with airflow thru the rad as the principal player, followed hotly, by the waterflow.
It's nice to have a system that is able to overcool, so the stat can do it's job.
 
Dana67Dart said:
Engines are designed to run in a specific temp range. As the engine heats up all the metal expands, the gaps designed in are there for that temp range, a lower temp range tightens up those gaps for better or worse.

I agree that modern engines are designed to run hot for emission reasons, and that might be hotter than is good but the modern engines seem to last 2 to 3 times as long as our 60's engines so they must be doing something right. I would go with what the factory used.
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Take a 60's engine rebuild it to factory specifications with roller lifters and put a computer-controlled fuel injection and computer-controlled timing on it and see if it doesn't last just as long...
 
Id run it as is. Maybe wrap the headers/manifolds to keep bay temps down? Manifolds are cheap, wrap aint gonna break them down.
 
MOPAROFFICIAL said:
If it's no longer tuned "stock" ....who cares.

They stat runs open, partially or full. They open before the rating as well, the rating means 'fully open by 160'
Run the temp where the tuner manual recommends ..because it's usually so the tune doesnt cause engine damage

Enjoy.
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Stat starts to open at that rating fully opened 6 to 8 degrees higher.
 
Dana67Dart said:
Engines are designed to run in a specific temp range. As the engine heats up all the metal expands, the gaps designed in are there for that temp range, a lower temp range tightens up those gaps for better or worse.

I agree that modern engines are designed to run hot for emission reasons, and that might be hotter than is good but the modern engines seem to last 2 to 3 times as long as our 60's engines so they must be doing something right. I would go with what the factory used.
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I think most of lasting longer has to do with overdriven transmissions , it is like not putting as many miles on the engine -----------less rpm.
 
j par said:
Take a 60's engine rebuild it to factory specifications with roller lifters and put a computer-controlled fuel injection and computer-controlled timing on it and see if it doesn't last just as long...
Click to expand...

^^^^I hope , I`ve done just that .
 
famous bob said:
I think most of lasting longer has to do with overdriven transmissions , it is like not putting as many miles on the engine -----------less rpm.
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Here's my theory on why they last longer..
think about being able to turn off the fuel injection and the ignition gets to burn those last bits of fuel before it shuts off. Then think of a carbureted car that shuts off the ignition and the Pistons are still going up and down sucking down the fuel and air on top of the cylinders which now at startup has washed the oil off..
 
/6 Matt said:
Changing the tune doesn't change how the engine is machined. Youre going to wear things out much faster.
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Machined...? NO.
180-220 is fine. Expansion factor is what speaking of. 150 or less would be a problem.
With more power comes more heat, tune is changed from stock, not within stock parameter. If his motor is shrouded by a tight compartment ..whos to say there aren't hot spots the gauge doesnt show in the back near the firewall...
...get a heat gun and zap some readings, then see. Your 360 say 0 intial timing too, you gonna run it that way..?
**** has expanded by 180, even if it didnt..its not blowing up over it.


famous bob said:
I think most of lasting longer has to do with overdriven transmissions , it is like not putting as many miles on the engine -----------less rpm.
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Yep and fuel injection. New engines dont get the fat or lean spells our carburetor engines do..and they auto adjust for optimal timing on the fly...the overhead cams outlive the old stuff mostly as well...the ring packages are better...the machining process is light years ahead of say what a 440 was carved on.
Its definitely NOT because of running temps like some in this thread are overstressing.
 
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gtokid1 said:
Stat starts to open at that rating fully opened 6 to 8 degrees higher.
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Did you take auto shop as a kid?
Go toss a 180 thermostat in a pot of water with a temp reading of 150 or so and watch it start opening.
Im old enough...unless something changed...by design, they are supposed to be fully open by the advertised rating .
 
j par said:
Here's my theory on why they last longer..
think about being able to turn off the fuel injection and the ignition gets to burn those last bits of fuel before it shuts off. Then think of a carbureted car that shuts off the ignition and the Pistons are still going up and down sucking down the fuel and air on top of the cylinders which now at startup has washed the oil off..
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True!
  1. Overdrives. A engine turning 2200 rpm's vs 1600 rpm's @ 60 mph. That's 36,000 more revolutions in 1 hr. Think of all the hours to get to 100,000 miles.
  2. Oils. Todays off the shelf oils are superior to yesterday oils (except for our flat tappet cams)
  3. As J par mentioned, FI vs Carbs. FI runs the car so much cleaner.
  4. Progression in the machining process. You didn't find Auto Gauges at the end of a CNC process 100% gauging every critical dimension of a machined part and feeding offsets back to the lathes.

.
 
MOPAROFFICIAL said:
..unless something changed...by design, they are supposed to be fully open by the advertised rating
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From the horses mouth...
Stant


THERMOSTAT TEMPERATURES
  • Thermostats have a “rated” temperature such as 180F or 195F
  • This is the temperature the thermostat will start to open, give or take 3 degrees
  • The thermostat fully open about 15-20 degrees above its rated temperature
 
Dana67Dart said:
From the horses mouth...

Stant

THERMOSTAT TEMPERATURES
  • Thermostats have a “rated” temperature such as 180F or 195F
  • This is the temperature the thermostat will start to open, give or take 3 degrees
  • The thermostat fully open about 15-20 degrees above its rated temperature
Click to expand...


To be a smart-*** , nil point...I use mr. Gasket high-flow thermostat. Lol
learned this a long time ago they start opening before the rating and they're fully open by/if not 90% .
Our shop teacher was the ****, we had cut down race motors and he drove a cherry 40's plymouth special every day.
He set up the hot plate...filled it...setup a thermometer in it and dropped a 180 thermostat in.... it started popping open at 150-155 slowly...he showed us the difference between design and actual function. They dont smoothly open either...they pop in increments is what it visually looks like.
I'm not gonna argue it. I know what I've seen ..and you know what you've read.
All good. It's not gonna help going back n forth over a thermostat
 
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