180 or 190 thermostat?

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Until I am otherwise told, I'm gonna say that 220-230 is my concerned range since the factory has the overheating mark at 250
 
nm9stheham said:
The 180 (or even a 165/160) can be used in winter to open the flow sooner and get heat to the heater core and the passengers. It can take a loooong time to get a 190 t-stat open on a very cold winter day with the car zipping down the road in all that cold air, and with a low HP, large surface engine like a 170 or 225.
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Incorrect.. see below..

Lonewolf3165 said:
The misconception being used here is the thermostat opens to provide the heat. It doesn't. It opens to allow the water to flow throught the radiator to cool the engine down. Even when the engine is ice cold it's circulating coolant through the heater core(as regulated by the heater control valve). The thermostat does NOT close off the flow through the heater hoses. By installing a lower temp rated therostat you actually are reducing the heat process by allowing the heated coolant to flow through the radiator sooner. A higher temp thermostat(like a 190*) would keep the coolant from flowing into the radiator until it reached the higher temp so that the coolant flowing into the heater core would be allowed to reach a higher temperature. However it doesn't make the coolant heat up any faster(from cold until say 180*). It just causes it to be heated longer before it's allowed to be cooled by the radiator after the t-stat opens up.

Think about it, a car with a t-stat that's stuck closed will still produce heat but will cause the engine to overheat. While a car with a t-stat that's stuck open takes a lot longer to produce heat & may never get very warm on a cold day.

For most of our classic A-bodies running on the steet a 180* t-stat is just fine. If in the cold winter you feel you don't have adequeate heat then maybe try the 190*.

I hope this helps.
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me too..

xxs2
 
Just as a side note on thermostats,,

There is also an optional thermostat that "fails open", which should be seriously considered, to save you a potential stranding, or worse, a serious overheat with consequences..
 
Man, I don't mean to be a hater, this is getting a little too cerebral, what's wrong with the stock one? Nothing. End of discussion, no need for 2 pages of bored dudes backyard engineering an answer. I swear y'all would argue over a fart in the wind.
 
PoisonDart74 said:
Man, I don't mean to be a hater, this is getting a little too cerebral, what's wrong with the stock one? Nothing. End of discussion, no need for 2 pages of bored dudes backyard engineering an answer. I swear y'all would argue over a fart in the wind.
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I sell parts for a living. The current overseas supplied t stats,don't even touch the quality of a actual Stant stat from ten years ago. I warrantied,so many the last 3 or so years.My recommended: Mr Gasket,or a Robert Shaw 180 "fail safe " stat. If it fails ,it fails with an opening.
 
Lonewolf3165 said:
The misconception being used here is the thermostat opens to provide the heat. It doesn't. It opens to allow the water to flow throught the radiator to cool the engine down. Even when the engine is ice cold it's circulating coolant through the heater core(as regulated by the heater control valve). The thermostat does NOT close off the flow through the heater hoses. By installing a lower temp rated therostat you actually are reducing the heat process by allowing the heated coolant to flow through the radiator sooner. A higher temp thermostat(like a 190*) would keep the coolant from flowing into the radiator until it reached the higher temp so that the coolant flowing into the heater core would be allowed to reach a higher temperature. However it doesn't make the coolant heat up any faster(from cold until say 180*). It just causes it to be heated longer before it's allowed to be cooled by the radiator after the t-stat opens up.
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Now that you write it out, I realize I was wrong to think and post my info; I thought through a couple of car heater systems I am familiar with, and can't think of one yet where the heater core is not bypassing the t'stat. My apologies if I misled anyone; BS (accidental or otherwise) is not what makes this site so good! Just when I thought I knew something.....
 
PoisonDart74 said:
Man, I don't mean to be a hater, this is getting a little too cerebral, what's wrong with the stock one? Nothing. End of discussion, no need for 2 pages of bored dudes backyard engineering an answer. I swear y'all would argue over a fart in the wind.
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I'm not sure how the other poster's feel, but I'm going to continue on the high road, trying to help,

But I'll continue to watch you muck about, demonstating your, hmmm.. intelligence (?), (for the chuckle factor).. lol

PoisonDart74 said:
this is getting a little too cerebral, what's wrong with the stock one?.
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Ahh,, they stick closed and cause overheat..

I thought it was supposed to be us old farts that opposed change for the better..

ROFLMAO....

have a nice day...
 
i'd say if you're in texas or sit in stop n go all the time then 180 is better

if you are up north and just do free wheelin' 190 is fine


the real debate is whether your block passages are all clogged up and your radiator is all clogged up . those are way more important than thermostat performance lol.

p.s. never run straight water you will have rusty sludge all through the block passages and when it freezes outside your freeze plugs will pop out, and/or you will crack the block

overheating will also mess your engine up; after a real good overheat you will start hearing knock knock noises
 
I hear you man. I mean that's what I was trying to say earlier, this is not a worried about overheating problem, simply where am I gonna make more power. Iv sat in traffic in 90+ degree weather surrounded by cars and it never even touched 205 and in it's entire life it's never touched 210.
 
inertia said:
I'm not sure how the other poster's feel, but I'm going to continue on the high road, trying to help,

But I'll continue to watch you muck about, demonstating your, hmmm.. intelligence (?), (for the chuckle factor).. lol

Hahaha Grant
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fnaramore said:
I hear you man. I mean that's what I was trying to say earlier, this is not a worried about overheating problem, simply where am I gonna make more power. Iv sat in traffic in 90+ degree weather surrounded by cars and it never even touched 205 and in it's entire life it's never touched 210.
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I'd say you are where you want to be, if you run too cool a stat and the engine can't run at optimum temp then cylinder wall damage can occur.
 
Abodybomber said:
I sell parts for a living. The current overseas supplied t stats,don't even touch the quality of a actual Stant stat from ten years ago. I warrantied,so many the last 3 or so years.My recommended: Mr Gasket,or a Robert Shaw 180 "fail safe " stat. If it fails ,it fails with an opening.
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Good to know, thanks for the tips!



fnaramore said:
I'm not sure how the other poster's feel, but I'm going to continue on the high road, trying to help,

But I'll continue to watch you muck about, demonstating your, hmmm.. intelligence (?), (for the chuckle factor).. lol

Hahaha Grant
Click to expand...




Oh boy, you guys are just baad to the bone on the internet aren't ya? :thumbup:

As far as I'm concerned, I'm not making any progress unless I gather enemies and trolls, so bring it on. Rock solid right here.
 
Dead wrong.
190* opens later & closes sooner= hotter heat. Not exactly what you want in summer driving sitting in traffic. Even a 190* t-stat won't give you heat any quicker, just more consistant hotter heat on cold days.

As other have posted the thermostat temp rating has little effect on maximum(peak running) temperature. However running the engine without one can cause higher temps because the water flows through the engine too quickly & doesn't allow for the necessary heat transfer from the engine into the water.

180* t-stat should be fine.
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The "too fast thru the engine" theory is frequently debated on forums all over with no resolution. I contend that's not the problem at all. Water is an excellent coolant, it both easily picks up heat and dumps it. Hard for me to believe it can be flowed thru the contortions that make up a coolant jacket too fast for it to accept only a very small amount of heat.

What does happen is that without a t-stat there is no restriction to flow at the outlet, so the coolant pressure in the block is lower and only due to those same contortions. With a t-stat block pressure is higher than cap pressure by some significant margin. With a lower block pressure it is easier to boil the coolant in localized hot spots. Once boiled it doesn't accept heat so readily and it takes a lot more effort to cool it back down.

Those disc type restrictors sold to replace a t-stat are OK for drag racing, but for any kind of road course, off road, or endurance racing they're junk. The restrictor for that type of use needs to be a venturi type of shape. Probably would need to be inserted in the hose *just* beyond the t-stat housing rather than in the t-stat's location to work best.

FWIW I ran a 195° t-stat in my old '67 Ranchero with a mild 302/AOD combo that saw a lot of desert towing miles. Ran it year-round with a Stewart Components pump and a cross-flow radiator. With an old 4 cyl hot rod that I had years ago I could tell by the power what the temp was. At 160° it made the most power, but at 180° it got the best mileage by a substantial amount. I ran a 180° in it. Didn't need the difference in power all that often, but being a poor working kid I needed the mileage.
 
Too fast thru the engine is a fact...... Have you ever looked at a Nascar or Winston Cup set up? Their upper radiator hoses are super small like 1.25" compared to our 2+ " Hoses. There is definitely something to be said on that subject.
 
Sorry, I see nothing in a small hose that supports the "too fast" theory. I see it better supporting my own theory. Search out "white papers" on the topic of block pressure in coolant systems. I didn't arrive at this conclusion by accident.
 
ntsqd said:
Sorry, I see nothing in a small hose that supports the "too fast" theory. I see it better supporting my own theory. Search out "white papers" on the topic of block pressure in coolant systems. I didn't arrive at this conclusion by accident.
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This is fun! I get to say this twice in a couple days lol Anyways, as a chemist I can assure there is no genuine pressure difference between the upper and lower side of the block because they are both connected and in the realm of science, the same system. By pressurizing them in the cooling system, you lower their vapor pressure, elevate boiling point and depress their freezing point. This transition is equal in all areas of the cooling system because when the thermostat is closed, their is still a path of travel through the radiator. Yes, there can be higher pressure areas due to temperature (compare inside the block and inside the radiator) but not enough to change vapor pressure. We can show this using the Clausius-Clapeyron eq. ln(p1/p2)=(delta heat of vaporization/gas constant)*((1/T1)-(1/T2))
 
The part that you're missing in the system description is that there is an active agent in the system that can force differential pressures, the water pump. Put a restriction in downstream of it and if the pump is capable of doing so that will raise the partial system pressure between the pump and the restriction. It won't raise the total system pressure, only the region between it and the restriction. Which further aids our cause by making the coolant around localized hot spots even harder to boil. From a pure science perspective it wouldn't look any different than an A/C system's pressure distribution.
 
If I may, if the pump was capable of making pressures so high as to change vapor pressure, then are you telling me that the pump is making about 20 or so atmospheres of pressure? Not the fact that the cooling system is a closed system, but the water pump is doing that? That is also not the correct use of partial pressures, I mean no offense, but partial pressure is directly dependent on total pressure and the mole fraction of the system. So unless moles are changing, total pressure is. Also I thought you were talking about no thermostat, flowing too fast vs. pressure difference causing the problem? So are you referring to the engine as the restriction? In that case... PHYSICS MAJOR ACTIVATE lolol XD I have fun haha anyways, in that case, of course the water is going to be moving too fast, its going to the avoid the restriction and take the easiest path of travel, i.e. avoid as much of the engine block it can and flow the great thermostat missing opening. For anyone confused by my claims of chemist and all, I double majored in physics and chemist :p
 
I'm using the term "partial pressure" to distinguish that a portion of the system is running at a pressure above the radiator cap rating. Without a restrictor or a t-stat this won't happen and the boiling point of the coolant, even though elevated due to the cap pressure rating, will be lower than with a restrictor or t-stat, and localized boiling will occur. To run without a restrictor means that the cap pressure will need to increase, and the rest of the system is probably not up to that greater pressure.
 
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ntsqd said:
I'm using the term "partial pressure" to distinguish that a portion of the system is running at a pressure above the radiator cap rating. Without a restrictor or a t-stat this won't happen and the boiling point of the coolant, even though elevated due to the cap pressure rating, will be lower than with a restrictor or t-stat, and localized boiling will occur. To run without a restrictor means that the cap pressure will need to increase, and the rest of the system is probably not up to that greater pressure.
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Okay I see what you are saying and I somewhat agree. Again it would have to be a good several atmospheres of pressure to change the boiling point significantly, but I could see that difference made to a very small degree. Keep in mind that water boils at 212* F and the addition of ethylene glycol already elevates that boiling point by a fairly large amount, so unless your engine is overheating, it wouldn't boil. I am willing to conclude that it is a mix of the two things, both lowered boiling point and moving too fast.
 
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