jpc647

So the parts store screwed up. They gave me a 160F thermostat instead of a 180*. It's funny because I looked at it to make sure it was the right size and the box says 180*. But inside the bottom shows 160.

Is that too low to run in a stock 1972 350? Stock Rebuild?


I usually run around 210* with the 195 thermostat. So I thought with the 180* and the new radiator I'd be in really good shape.


The car is all apart, and I didn't want to run back to the store, cause it's like 20 minutes away. But at 160, my car is going to theoretically be running somewhere around 175*/180*. Which I think is a bit low?

Should I even be questioning this? I should probably just get off my butt and go get the right one, right? ha.

GEARMAN69

160 is fine in South were I am . If your In a cold environment a 180 would be better. What state are you in?

jpc647

I'm up in mass. But I don't drive the car in winter. I start it occasionally during the winter, but only drive it say April-October(maybe early November).

I know the thermostat only maintains a lowest operating temp for the car. But with the new radiator, I was worried it might run too cool.

jensenracing77

If it don't get to 180 to 200 in normal driving I would change it to a 180.

GEARMAN69

Fortunately you have a low compression 72 so no pingy issues running 180-200. it wont run cooler than the thermostat normally and with AC in the summer it may still stay 170-180 in traffic and just cool down on straight driving in between. I would use it. if not already done a performance minded tune on the quadrajet would help as well to see the torque / power improvement as well.

dualquadpete

I like to run 160 t/stat. as it gives me a little more lee way in heavy traffic to not get 'too" hot, especially in line up crossing border to US. one year I hit 235 F while inching forward to customs on a very HOT day!!! Usually run at 180 to 190 while going down the hwy. on hot days even with 160 T/stat!!!! Electric fan also helps!!!

Fun71

I ran a 160 for decades, but I live in a hot environment.

I'd run it and see what happens. If the engine stays too cool for your liking, it takes only 20-30 minutes to put a 180 in.

Ozzie

I'd use it. Oldsmobile stage II 8 cylinder engines often have problems running too hot. Few run too cold in the summer.

m371961

I am a cooler the better guy. 195 came about with pollution equipment. As long as it has adequate heat. And a cooler thermo will give you a margin of error on hot days in traffic.

MDchanic

The engine should run more efficiently, with more power, with a 180° or 195° thermostat.

As noted, since you have a low compression engine, there is minimal likelihood of detonation, which can be improved by lowering operating temperature, and there is really no other valid reason for using a cooler thermostat (if you have problems keeping the engine cool, then you need to look to your radiator, fan shroud, fan clutch, fan, water pump, or coolant passages for an answer, rather than installing a cooler thermostat, which doesn't even qualify as a Band-Aid).

That being said, 160° is not likely to hurt anything or cause noticeable performance problems, so there's no strong argument against using it, but personally, I'd spend another $5 and buy a 180° thermostat.

Bottom line: It's really not a big deal, and not worth losing any sleep over.

- Eric

Ozzie

I realize that by operating at a lower temperature probably "efficiency" and "emissions" are hurt, since those seem to account for the rise of engine operating temperatures through the years; but I've often wondered about the "downsides" of having reduced lubricant viscosities, increased fuel percolation, greater differentials of dissimilar metals, and a harder life for gaskets and seals over the life of an engine when operating at higher temperatures.

MDchanic

I am not an automotive engineer, but in theory, higher temperatures provide better fuel atomization, which reduces fuel condensation on cylinder walls, which tends to wash off oil, and so reduces wear. Higher temperatures also better eliminate water that may have entered the crankcase and oil system, and thus reduce corrosion.
Engines that were designed to run at 195° have their metal expansion rates optimized for that temperature, so the relative dimensions of components at lower temperatures are not optimal.
Modern gaskets are also designed to withstand standard operating temperatures.
In a Model A or a Model T, or a curved dash Olds, your mileage may vary.

- Eric

My442

180

83hurstguy

My old 307 loved a 160* stat, ran better the cooler the water was. Engines on the dyno make more power with cold water in the 130-140*F range. Boat engines never clear 160F (typically way cooler), and there are a ton of Olds in marine service. My new 468 has a 160*F robert shaw waiting for it. You'll be fine.

cutlassefi

X2, especially with iron heads and on gasoline.

m371961

I always thought that higher engine temp to a point would give better combustion, but sucking in hotter air underhood negated any advantage of a 20 degree higher coolant temp. But I ain't no expert.

oldcutlass

Yes, engines will make more power but there is a wear tradeoff running lower temps. Running a 160 is a band aid to poor cooling systems it will not cure a high temp issue.

oldsmobiledave

Take it back and get the 180. You were on the right track.

therobski

My 67 modified 455 with aluminum heads, Torker, with an aluminum radiator ( lots of aluminum to help dissipate heat) and a 160 degree thermostat I think for this set up is the way to go. I can run this car in Dallas heat and barely hits 170 in 110 Texas degree heat. With timing at 20 degrees and 36 degrees total and no pings to boot! As little as I used to drive the car I'm, along with a quality engine build I'm not to concerned about engine wear.

76olds

Put-r-ther,... very true as to what I've heard in the past.
When I worked in a rad shop back in the day, Guys with race cars mentioned a 160 deg thermostat would keep the front pistons from expanding properly and wear prematurely. Due to insufficient heat expansion.
I've only heard this first hand from the guys talking about it when getting 4 row rads installed.
They also mentioned the engine gums up quicker with condensation not being able to burn off with low temps. I'm sure the synthetic oils today would combat the condensation, although I would think the heat expansion properties would lack in our old engines just a Eric mentioned the wear factor running a 160 stat.
I run a 180 myself in my stock 350 + bolt on mods. My temps range from 190-200 with a be cool 2 row rad/no A/C

Hope this helps
Eric

pmathews

When I ran a 160, I noticed a lot of blow-by, but when I changed to a 180, the blow-by was reduced, so I think there's good logic behind allowing parts to reach the proper operating temp.

Pistons are aluminum, and that expands at a different rate than the iron cylinder walls, so it makes sense that running the correct engine temp will help with clearances and reduce wear.

Ozzie

In my Oldsmobile Parts Book, for group 1.246 (Thermostat, cylinder head water outlet) it shows two thermostats for the 1935-1959 engines. Part number 563219 is for a 160F thermostat and 563311 is for a 180F thermostat.

In my Chevrolet Parts Book, for group 1.246 (Thermostat) it shows for the 1958-1959, series 3-4, 151F, 160F, 170F, and 180 F thermostats.

In my Ford parts catalog for the 1973-1978 460 engine, thermostats of 160F, 180F, and 190F are shown as approved for replacement.

While it is true that there is an expansion differential between dissimilar metals, I doubt that, within any one engine series, the manufacturers are setting their piston to cylinder clearances according to the temperature rating of the thermostat since they approve so many different ratings for replacement.

If you have a "worn" engine going from a 160F to a 180F probably should reduce the piston to cylinder wall clearance, hence reducing the blow-by, as the coefficient of expansion for aluminum is greater than that for iron.

To a "degree", the question remains, what is "proper" and "correct", as all of us do not have the same circumstances.

Koda

I guess I'm an automotive engineer, although I design equipment to build the cars, not the cars themselves.

My stock temp discussion is as follows. The radiator needs to be more powerful in terms of cooling capacity than the car can make heat. The thermostat will then regulate the flow of coolant to keep the car where it should be, and a lazy, sort of accurate temp gauge helps make it look at 50% of the range, ie, needle straight up is good. If you install a 160 degree stat, and the car does not sit at 160, then you have a weakened cooling system that, while it may not be performing per spec, it is performing.

Example. I have a car, which was indicating 250 on hot days on the factory gauge. I installed a mechanical backup to confirm the gauge. I installed a Stant Super Stat 160. The two gauges match, and now the car will only ever get to 210, maybe 220. The original emissions thermostat was being lazy, and the larger flow thermostat helps.

Do I care that it's a 160? No, it gets hot enough because of the bad cooling system. Will I put a higher stat in there once I recore the radiator, replace the water pump, and do what I can for the cooling passages? Yes. The only drawback to a 160 thermostat, with an ailing cooling system, is that the car might not come to temperature soon enough for your liking in the winter.

Now, onto the mechanics of the situation. Engines are designed for a specific range. An older engine might have less slop in it at higher temps, but you'll get worse mileage and higher friction losses. If you never really warm the engine up, you'll get some moisture and buildup issues, but, for running an engine, I would say anything on the gauge ie 150-230, is ok. When an engine is COLD, as in just started, there's a point to being easy on it, but I don't think that anything on the normal range would harm it, especially since the pistons always have clearance to the bore until you overheat and seize; it's the rings that touch the cylinder walls, as we all know.

I do think this is a case of over-paranoia. Nothing wrong with that, take care of your stuff, but it really won't matter, ESPECIALLY if you have a less than perfect cooling system. As long as the car gets up to 180-190 or so, you're good.

As for the power stuff, you do want cold air (for density). You want warm fuel, for better atomization, but not enough to boil. You want the viscosity of the oil to be light enough to reduce drag, but not to compromise its lubricity. Your ideal situation is highway driving, with no traffic, on a low humidity day with no dust, about 40 degrees, but sunny. This keeps the tires and the car warm, but the intake charge is cool, dry, and clean. There is something to be said for OAI.

GEARMAN69

On the 160 in milder climates also consider running lighter oil like 10W30 if your a 20W or 30W guy

70-442-W30

How timely for me to run across this thread. But still totally confused and unsure what to do in my scenario. What did the 1963 F-85 Deluxe come with stock? I bought a 160 the other day but now you guys have me rethinking it.

Ozzie

As far as I know, the full size car came with a 180F, but I don't know about the F-85. You'll probably need either someone who bought one new or someone with the right specs or parts book from 1963. Since the engine is aluminum, the 160F might be a good choice. Without additional information that's probably what I would have chosen.

ignachuck

I know that I have an older car than you guys, but I was taught and still believe that cooler is better, so I have a 160 in my '56 and I really like looking at a low thermostat on a hot summer day, stuck in traffic.

MDchanic

170°F

- Eric

MDchanic

As the years went on, engine designs and metallurgy changed.

Cars from the '40s and '50s were happier at cooler temperatures (up to a point), and some even use 140° thermostats in them.

Cars from the mid-sixties onward were designed to run at 180° to 195°, and this is the optimal temperature range for them.

- Eric

70-442-W30

Thanks everyone. I'm just going with the 160 then unless I hear some advice against it. I'm interested to see what is currently in the car.

MDchanic

Considering that if there is a 5% tolerance on thermostat accuracy (which is probably fairly optimistic), then a 160° thermostat will regulate coolant temperature to somewhere between 156° and 164°, and a factory specified 170° thermostat will regulate to between 166° and 174°, I wouldn't worry about it too much, but you could just buy a #1199784 thermostat for $10 on eBay, if you've got any concerns.



- Eric

70-442-W30

Wow Eric, that's a bargain. One of the few NOS parts that haven't increased 10000%.

jensenracing77

They had a 168 when new but they were listed as a 170. On the 61-63 f-85 model I recommend the 160. It is the only cars I ever run less than a 180. The car will still be running hotter than 160.

jensenracing77

Did not see this before I posted the other post. These pop up on eBay fairly often and are a great thermostat. I have a couple of them that I keep around.

Leadfoot

Koda hit all the nails on the head, IMO.

A lot of people seem to misunderstand the thermostat's function. (Assuming a relatively stock setup and not a highly modified or racing application), it does not directly regulate the engine's upper temperature limit. It only regulates the low point of the engine's running temperature. The rest of the cooling system determines what the high temperature will be. If your cooling system is very efficient, the thermostat prevents the engine from running at a temperature that's too low. As some others have pointed out, changing to a lower temperature rating will not, all by itself, make your engine run cooler. It will only slow the warmup process by allowing engine coolant to enter the radiator at a lower temperature.

Likewise, if your cooling system is very inefficient, your engine will run hot regardless of the thermostat's rating. A lower stat rating will only delay the inevitable (for a while).

The thermostat is designed to keep the engine from running too COLD.

When most of our older cars were built, it was still common practice to change the thermostat in spring and fall. The reason for this was to allow faster warmup in winter and quicker (but not more) cooling in summer. Beyond that, it was the efficiency of the entire cooling system that ultimately determined your engine's operating temperature. It was very common in those days (during winter) for people to place a big piece of cardboard between the grille and the radiator. This kept some cold air off of the radiator so the engine could run warmer in very cold ambient temperatures. Changing the thermostat to a higher temp rating accomplished the same thing in a much more reliable and predictable way.

With engines that are not run a lot (as many of us have), it's even more important to make sure the engine reaches the designed operating temperature in order to burn off condensation and provide proper lubrication. Installing a lower temperature stat in an engine that is not run a lot may well do more damage than good.

That's my $0.02.