Help me choose, I'm torn between a 160* or a 180* high flow stat. Engine is 1969 440 375 horse mostly stock except for a small Comp cam and Edelbrock performer intake, 391 gears. Car is a 69 Dart GTS so because of the small engine bay and big 440 motor not much air can circulate around the motor under the hood. What thermostat would you recommend? Thanks..

I think the 180 is even on the low side, DEFINATELY NOT the 160.

I run 160 in all of my pump gas streetcars, some run 180F+ and some run hotter
If you do short stop and go driving with trips less than 5 miles then it doesn't matter as it usually takes my motor more than that distance to get up to 160F
Cold motors wear, hot motors don't wear as much or as soon

I would suggest the 180 if you plan to drive the car (ie. not drag strip only).

Keeping water temp at least 180 helps reduce bore wear from condensing fuel. Also keeps temps steadier when running so the tuneup (mostly timing) can be dialed in correctly. If you run a 160 temp will be near 160 sometimes... and probably warm up to 180-200 sometimes under load in warm weather. If timing is set to avoid ping at 160 it may ping at 180-200. Similar effect on fuel mix and jetting. Actual temp under heat and load will depend on cooling system performance... a 180 stat should be fully open by about 185 degrees.

As long as your cooling system can handle the the load and maintain the temp, then you definitely want the 180.

I also run a 160 in my street cars, my big block stroker Duster runs at 178 degrees all day long with an aluminum radiator, flex fan, good shroud, and 160 stat.

I would suggest you also drill a small weep hole in the thermostat, I have had problems with air trap before and the thermostat won't open.

^^^ agreed, a 1/32 hole in the "flat" is plenty & also lets you pretty much completely fill it completely the first time as opposed to waiting for the stat to open. this elims a potential burp of coolant out of the rad neck onto your pristine eng & it takes care of hot metal areas that have no coolant on them when its first fired.

Just leave a heater hose off while filling the radiator and all the air comes right out, you can hear it. When the fluid appears at the heater hose nipple install the hose and fill the rest of the way. Done it for years on customer cars, saves lots of time and headaches.

I learned something today.

old dogs and new tricks, ehh Robert

today is my day

Uh, what about the air in the heater???

The heater has coolant in it already, just a little air in the hoses. Unless it is a fresh built car with everything dry. The tubes at the heater core are at the top of the core on regular heater B C & E bodies. Even if you flush it with the garden hose it still has liquid inside the core.

But Dave you are correct, any air in the heater core and hoses will still be in there. You can take the hose off at the heater core and do it but it makes more of a mess.

Just try it one time and you will see that it works well. Yes you may have to add some more after the stat opens, but it won't be another 1-1.5 gallons like before.

And if you waste time drilling a hole In the thermostat you still have the same air in the heater core and hoses, no difference.

I don't have a heater core or heater hoses in my car but whenever I change fluids I drain my radiator and both sides of the block, then I use an 'Airlift #550000' tool to suck all the air out of the system, then I stick the hose from the kit into my bucket of new fluid and it automatically pulls all the fluid into the cooling system with no air pockets. Best tool I've ever bought.

And I also drill a couple small holes in the base of my thermostat.

All this is good info, but I think we got away from the topic. What about the thermostat temp recommendation. Would you run a 160* or 180* stat? if you were me. Thanks.

at least 180 & on drilling the stat it takes longer to find/chuck up the 1/32" drill bit than it does to drill it. then I chamfer that mini hole with a slightly larger bit by hand, takes 5 seconds.

Running a 160 just delays the onset of heat. Might work as a restrictor once it opens and that might work out for you if it holds the water up enough in the radiator to lose the heat. I found replacing a 160 in a car I had made the oil stay much much cleaner. I put the factory 195 in it and it stayed right on the stat all the time. Even idling for long periods with no shroud.

The real deal is system capacity. Get that right and it will be fine. Engine masters did Dyno testing and a clutch fan without a shroud was the best engine driven setup. So I'd run a 180 or 195 with a big radiator and call it good. Get outside intake air piped in and you'll have a nice rig.

There is a lot of info on this subject on the WWW. Here is just one link, but it is consistent with most of the others and is easier to read than some others. What it says is that there is double the engine wear at 160* as there is at 180* with no appreciable performance gain.

And if it matters, I always drill a couple of small bleed holes in my thermostats. Which, after some bad experiences with other brands is only the Stant Superstats.

http://www.carnut.com/ramblin/cool3.html

Thanks for the link DaveRS, interesting reading. Most everyone here seems to agree, I should use a 180* stat for my application. I'm going to order a Milodon high-flow 180* stat tomorrow. Thanks everyone for your advice, you guys a great.

I like 180 myself with that setup. I have always been tempted to run a cooler one for obvious reasons, and more than once found myself going back and having to put in a hotter t-stat because engine never reached a good operating temp.

The only part you all got correct was that the cooler operating temperatures creates more wear. The year is 2017.

Today's gasoline requires 195 DEGREE MIN OPERATING TEMP.
It is not the same fuel as in 1970. If you do not run the engine hot enough the fuel will collect in the intake manifold and burn off n the cruise mode, flip flopping the air fuel ratio. This is not conjecture, hearsay or i read it on the internet, but information from instrumentation and years of tuning experience. Ethanol laced fuel requires a different tune up that non ethanol fuel. the A-F ratios are different......gee wilikers Mr Wizard...

60% distilled water 40% antifreeze and a bottle of coolant additive.

If you guys would pay attention and retain just a little knowledge this forum would be a better place.

195 is not hot
210 is not hot
195-210 is the normal operating range where your car should run
220 is warm
230 is hot

Lol, you can stare at your 195-210 temp gauge all day if you want, not me. Lots of ways to build and run these cars, it's all personal preference. I've been driving 9 and 10 second cars on the street for decades at lower temps, although you may be referring to bone stock motors.
And I will admit that I want to install a 180 thermostat this Fall since my car runs a little too cold in the Fall/Spring.

No it isn't. It's a matter of data and testing vs neanderthal thinking.


Come out of the cave, that bright like is knowledge.

Ok I'll try but I ain't happy about it

I appreciate learning facts, but nobody's gonna kill their motor with a 160 stat, alot of racers don't run a stat and let it free flow. Now back to my cave.

just to throw some gas on this fire, my 440+6 runs way better with a 195 as opposed to the 180. i tried it based on the recommendation by Tom in his 6 pack tuning guide. if you over heat with a 195 installed you have a bigger problem than the thermostat.....

Here in Texas Gulf Coast, my thinking went to use a 160 stat; seemed counterintuitive to use a 180 or higher. Had pinging, spent a lot of time chasing the timing. Finally, emerged from the cave (like the metaphor!), read Mopar's Big Block tome, "160 thermostats should NOT be used in other than high endurance racing vehicles. Use of 160F thermostats in vehicles other than this can cause serious engine damage." Who am I to argue with the engineers who design/build these motors. Went to 180 stat, timing was a lot easier to manage and dial in. Engine temp still the same 190-205.

Only used 195s in my rides...never anything cooler. I want the motor to come up to a hot steady temp and if the cooling system has the capacity to keep it there you've got a solution.

Then why is the stock gauge at 180 when at mid point and at 210 in the overheated range. Old iron doesn't like heat as the new junk today.

I had issues for several years regarding the engine temp I use to belive you could not get the car too cool WRONG Just switching to a warmer 180 resulted in a car that et over .3 faster due to no hesitation Now the lowest stat I run is 180 and lean toward 195 Its like a MSD unless you are racing run the factory temp MSD are Ok for race cars but don't live on the street very long

My engine never warmed up enough to run right with a 160.

The only advantage to running a colder system is the intake might be a couple degrees cooler. EVERYTHING else will be too cold. pistons, oil, cylinder walls and bearings.

There is also NO advantage to a slower warm up. Which is another reason a closed thermostat is better than 1 with a drilled hole in it. A few hot to cold cycles will rid of any air if you have a coolant recovery system.

I agree on a fast warmup being far beneficial to get out of that high wear "zone". I drill a very small hole only for easy first time fillup, not near large enough to have any effect of cooling.

I am not going to continue to provide any more mopar technical support here on moparts. As I provide technical support in my employment on very very complicated technology this is not my first technical information rodeo. I might have a clue on how to analyze information and create proper technical documentation/information. The six pak tuning guide is a perfect example of well researched information that does not get used before coming on here complaining that the damn thing doesn't work correctly and getting bad advice from the uninformed.

Some of you are very uninformed and are incapable of comprehending anything that makes good sense. You pollute threads with hearsay, old wives tales/opinions and refuse to use good technical advice. Diplomacy prevents me from speaking directly to a few of you and telling you in plain english that children should be seen and not heard.

Good luck with your 160 or 180 degree thermostats in your "old iron" and your fast wearing - poor running engines. BTW in 1970 the thermostats were 190 degrees from the factory...

They may not kill there motor,but it will eventually shorten it's life span.Also,a real race engine is rarely street driven and the percentages of each are quite different,the OP ask about a street driven car,not a race car.If your 160* makes you happy,good luck with that.

i will miss your wisdom tom. you are spot on about using a high temp 'stat, and today's fuel, in my opinion, requires a higher engine temperature to burn correctly. my '78 E58 cop motor came with a 195 'stat, and it ran 195-200 down the road in my '38 plymouth coupe. in high ambient temperature with stop - n- go traffic, it ran 210-215. this is with just a re cored stock radiator and a stainless 5 blade flex fan [no shroud]. it made good power, got reasonable gas mileage, and never puked when shut off. always started instantly when heat soaked to boot. i have a buddy that has a 55 chevy with a '95 LT1 that gets hyper when his temp hits around 200. most vehicles today run a 205-210 'stat. i know some will mention the newer machining operations and the computer controls as the reason for higher 'stats, but unless you are pushing 230+, i for one, wouldn't fret a bit about a 200-205 temperature reading. i understand your frustration completely because i have experienced some of your same deals with guys around here. i try to help them through my knowledge gained by the mistakes i have made in the past so they will save time and money, but they just want to label me as an "old, crabby know-it-all". any more, i just let it roll off my back, even though in the end, their results want me to say : "i hate to say i told you so, but......" and now, i'm being plagued by "old timers", and have to watch what i say because sometimes i get confused and blurt out wrong stuff. however, i am quick to "own up" to being stupid, when others seem to try blaming something else when things go wrong. just my opinion tom, but i for one will miss you.

Hey dont leave us! Yes there's some less than perfect peoples' attitudes here & some misinformation but we need all the (correct) tech that be mustered and when the student is ready the teacher will appear (actually when the student is ready he will grasp what the teacher has been sayin all along!). right now it is not about the students but about the teacher & I would suggest you get drunk/get laid/take a vacation & come back & you'll be fine. we need you! I read your sixpac tuning guide & it was awesome, I dont have one (I have dual fours) but I'm gleaning from it. I understand they are complicated but are awesome when setup right.

Awwwww, come on........Don't deprive the rest of us due to a couple of Neanderthals. It's not fair. Besides, we are loosing experience here at a rate that is unsustainable. Everyone has an opinion and in this Facebook society, everyone just HAS to share it. Even if it has no basis in fact. Unfortunate, but true.

So, why not come on back and just ignore the ignorant? Some of us would appreciate it.

Come back Tom....Come back. Gosh I didn't mean to cause any hard feeling between members when I originally posted this question. I just wanted peoples opinion on the best thermostat to run in my mostly stock street driven 440 A-body with its stock factory cooling system, because it has a tendency to run a little warm. I very much appreciate all the response and opinions I've received. I feel this Forum is a wealth of info and I've learned a lot in the short time I've been here. Thanks to everyone who replied.

I've run mopars with 160 and no stat for over 50 years...pump yourself up with "ideas" and feel great while MY test of time has succeeded over and over.

I think this still applies !


They may not kill there motor,but it will eventually shorten it's life span.Also,a real race engine is rarely street driven and the percentages of each are quite different,the OP ask about a street driven car,not a race car.If your 160* makes you happy,good luck with that.

I agree that we are talking about vastly different engines, my cars are street driven so they are not all out race cars, but obviously my 600+ HP engine is gonna create heat much quicker than a stock type motor. I've never had a bone stock motor in an old Mopar my whole life so I should have just avoided a thread like this as I usually do.

For the original poster, these guys are right, you should run a higher temp thermostat for your combo. My motor with a 160 will run 178 all day, and sitting in really bad traffic on a 90 degree day it will creep up to 190 or 195 which is fine, I'm sure my cooling system isn't perfect but it certainly does the job as the temp will come back down once I'm out of the traffic, maybe a 180 will make it more stable.

Sometimes our street/strip motors will only be at 140 degrees in the staging lanes and run the same 9 or 10 second ET's as they do when fully warmed. Stock motors are a different ball game, 3 tenths faster at 20 degrees warmer is a HUGE difference.

I'm gonna try a 180 after reading some of this info but I know when I did that years ago the temp seemed to climb over 200 while in traffic since the temp was already 180 or higher to begin with, but I doubt I had a great cooling system back then.
And I know for a fact my motor is not happy cruising around at 210 degrees.

As far as the name calling and stuff, that's pretty sad, we used to be able to debate or explain stuff here on this forum without that kind of behavior but I have thick skin, so no biggie. I'll try to keep my knowledge and years of experience in the Race Section.

During your "test" how many of those engines were torn down, to check bore wear, and at what milage was that done? How much was the bore wear?