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Thermostat temp

8K views 24 replies 13 participants last post by  compje 
#1 ·
Okay, need more education from you old timers ,(smart guys),with experience. Currently, I have a 160 regular thermostat. This was put in when I put engine together 10 years ago, thinking it would keep things cooler. I've never overheated in traffic, and it stays below 190 at a steady 2000 rpms on freeway. I recently found a new high flow 180 thermostat I must've bought years ago. My question is: would it be better to put the new one in and what kind of difference would it make with a 180. It seems like it would let engine warm up faster, but is there anything else?....would a 195 be better? It's a warmed up 460, bored .030 over with a true 450-475 hp.
Thanks as always,
James
 
#3 · (Edited)
Generally speaking warmer is better for a street engine. The idea behind warmer is that the engine needs to get hot enough to evaporate water from the oil. A by product of combustion is water vapor and some of that water vapor finds its way into the crank case. Additionally, the intake needs to get warm enough to keep the fuel properly vaporized and some believe a cold engine will cause fuel vapor to condense and form droplets in the intake that lead to higher emissions, uneven fueling and general poor running. I have no idea whats the idea is behind a 160 other than marketing. Perhaps someone else knows. If someone is over heating with 180 or 195 there's a deeper issue and a 160 will only delay the problem ,sometimes sufficiently so that it seems to solve the problem.

Empirically speaking...I have an electric fan controlled by the ECM and I can regulate the engine temp to with in a few degrees. I've played with various temps. My SBC 400 seems to have the best idle at about 212 degrees. To me this suggests at 212 the intake is getting hot enough to fully vaporize the fuel. Its my understanding that some ECM's allow the engine to get as hot as 220 in normal running. In the end 212 seemed a bit high to me so I settled on 195 thermostat and fan on at 200 and off at 196.

So put in that 180...this is hotrodding in some respect...see what happens. I'd go out on a limb and say 195 with alu heads and intake and 180 with iron heads and intake.
 
#8 ·
I think the 160 stats got famous back when off the shelf "performance chips" came out.Most of them were tuned for operation with the 160* stat.Alotta ppl figured"Hey,that'll make it run faster !!! I'm sure they have other uses,but,that's when I started hearing about it.
 
#4 ·
I've had nothing but troubles with the HI-Flow thermostats.. The Mr. Gasket I tried lasted about 10 miles.. I always ended up with the Stant thermostat with a 1/16" hole drilled into it..

You motor temps should cycle around the thermostat rating, if they don't you have cooling/tuning issues...

When I switched to a Champion aluminum radiator, I had to change my thermostat from a 160 to a 180, my Pontiac 455 was running too cool...
 
#5 ·
Thanks guys. I've got the 180, so I'll try it. The thinking about heating up faster was that it would stay closed until a hotter temp...poorly worded on my part:spank: I think my radiator and dual fans are marginal, but ZERO issue at cruise speed, so I guess I have to avoid loooong idles during power tour. Again, thanks for the feedback. Point of note, driving it to work the last couple of nights, mostly expressway; it stayed around 165 with outdoor temps in the 65 degree range...maybe the 180 will lean it out a bit. It does run a little rich even after optimizing the vacuum at idle.
 
#9 · (Edited)
when working for ford in the 70's ,180 was the recommended thermostat. The 460 is a lot of engine and has a reputation of running hot, however this is usually traced to a partaly restricted radiator on stock vehicles, and an under sized radiator and (or) inadiaqite air flow through it on modified cars and street rods. A 460 requires as big and thick a radiator as you can cram into your car. look at the huge radiator in a Lincoln MK4 or a pickup. I have a 460 in my 67 cougar and the motor runs 20 degrees cooler with the rear of the hood blocked open an inch (as an experiment) . the Shelby big blocks had louvers on each rear corner to help cooling . that is my next modification to my cougar.
 
#10 ·
The engine will run better at or above 180-200 degrees. What most folks forget is that it's a pressurized cooling system. That radiator cap, hopefully a 15 pounder, will allow the boiling point of water at sea level to go from 212F to about 245F. The NA$CAR guys use a 25 pound cap and as a matter of course run their car in the 250F range. A high flow thermostat like a Stewart which is a modified Stant or Robertshaw will allow some circulation during warmup to keep from having hot spots. Then you can use a water wetter like Red Line to help as well. Mine went from running at ~190+/- 5 to hard to keep 180 since starting to use that wetter. I try to avoid anything that has Mr Gasket on it - some is just reboxed name brand, other is low end crap, all of it with a mid to high end price.

As far as a 460 running hot - of the at least 4 vehicles I've had in the past with that engine, never has a single one been a hot runner, with 3 of them pulling heavy travel trailers over 30 feet including through Death Valley and over the Rockies.

Dave W
 
#12 ·
nothing wrong with any of this- I'd just like to add that adding coolant to your water works as well, and is a much more common approach. Also, 180 is on the very low side of what I'd run on the street- and only if the car had a borderline tune and it needed that crutch. 160 stats have a very very small range of application in my book.
 
#11 ·
Love this site..always good feedback. My plan is a 180 high flow, new 15 psi cap, water wetter with about a 20-30 % coolant mix. Now another question. I understand increased psi cap and coolant raises the boiling point of the liquid, however; even if the boiling point were raised to 300 degrees F, aren't temps over 220 bad for the engine, seals, gaskets, etc?:sweat:
 
#14 ·
Low temp t-stats are mostly seen in raw water cooled marine engines to reduce salt buildup in the block (cooling system is unpressurized and being fed salt water, so lower temps minimize boiling risk and salt deposition).

Fresh water cooled (coolant loop with a heat exchanger) marine systems often use hotter t-stats, minimally 160*, many are 180*.
 
#17 ·
Around 200 will work just fine - but you may have to move your timing back a degree or so if you are running on the ragged edge of ping. Best combustion temp is during hot weather. Us here in the Nawth with carbed cars are all too well aware what happens when it gets cold. The choke opens slower, the gas mileage get worse - even with the choke fully open. It just takes more energy to maintain combustion chamber firing temperature.
 
#18 ·
dave w is entirely correct in that a factory designed truck or car with a 460 will pull anything you can hook to it provided the cooling system is in good shape. the engine has a undeserved reputation in my estimation and experience. in 40 years with ford ,99.9 percent of overheating problems were caused by problems with the cooling system ,not the base engine. It is almost a given that if you are on this site that your vehicle is modified in some way and the horsepower is probably raised higher than stock through modifications of some sort. a basic conversion is 1hp=2545btu/hr . So no matter how you cut it, a high horse power motor requires a lot of heat removal, which has to be transferred to the surrounding air. electric fans and fan shrouds help pull air through the radiator to increase the heat extracted from the coolant, however we must be aware that all that heat and air flow has to escape from the engine compartment which I was trying to point out in my prior post.
 
#19 ·
Drove the truck tonight about 20 miles on expressway. Temp stayed around 180, matching the stat. Usually at speed with the fans off, at night, it wouldn't get over about 165 with the 160 stat. It does warm up quicker with the 180, as it holds the water longer. I noticed it went to a good idle quicker..guessing leaned out quicker.

Yes, looking for ways to vent engine area without punching holes in hood. Since I have a reverse tilt hood set up, might try putting rear of hood up an inch or so. This would provide a little relief at idle.
 
#20 ·
An inability to cool at idle is a sign that there is not enough air being pulled through the radiator.

First thing is to be sure the core or if it has AC the condenser is clean of bugs trash or corrosion on the fins and tubes. That the fins are straight, there is a comb like tool at the parts store for correcting this condition if needed.

The next is fans, whether driven off the coolant pump or electric a shroud that encloses the permiter of the radiator and connects that with the fan or fans is absolutly necessary for pulling air accross the the entire surface area of the core.

Last is cleanliness inside the cooling system. There should be at least a 50/50 mix of coolant (use anything but Dexcool) and either distilled or de-ionized water. Tap water even that coming through a water softener should never be put into a cooling system. Ordinary water including softened water contains dissolved minerals that precipitate out to form scale on the metal surfaces inside the cooling system and or have loose ions that corrode the metal parts which not only forms a scale but etches holes into the thinner parts. Scale acts as an insulator slowing heat transfer from the engine to the coolant and from the coolant to the radiator core. holes of course form leaks, often it's the scale that's keeping the coolant in. Then you find that when the radaitor is cleaned it suddenly leaks.

Bogie
 
#21 ·
Thanks. Yes, the weak link is the 2 cheap 12" fans. I've never gotten over 210, but don't know how long I could idle in severe traffic. I have a two speed Taurus fan I bought years ago, but not enough room. ..it moves a BOATload of air. May try to mount it offset from center. If that doesn't work, I will look at two quality 12 inches. The rest is good....a cross flow radiator would be better I'm told, but a $1000 radiator is not in budget. For now, I'll avoid any looong idling if temps get over 110. The temp overall seems steadier with the 180 high flow. Thanks for all the input guys!

For another thread maybe, but what brand makes great 12" fans?
 
#23 ·
ditch the dual 12's. Head to your local recycling center or ebay and get the eletric fan from 90's V8 crown vic. It's got curved blades and at full power its tornadic. I used a electric fan controller that would start it a 50% and run it up as the temp raised. It seldom got over 50 percent and would usually come one and go off a few minutes later even on a hot day in traffic.
 
#25 ·
Marine engines run a cooler stat because the cooling medium is water. They don't have the added benefit of a coolant that has a higher boiling point. (except for salt water autoderivitive engines with an exchanger)

Modern efi engines run a bit richer when cool to aid in warm up etc. When we look at the stoichiometric, side of this, we can make a bit more power slightly rich as compared to the 14.7 or so mixture. So, a trick on modern engines is to run them cooler to trick the ecm into a bit richer mixture.

Now for the fun part. If we are looking for power on a carb engine think about quench area or effect. The burn of the mixture falls off near cold iron or metal. Hotter is better until we reach a point that we have detonation or heated incoming charge.

Keeping moisture out of crankcase oil,,,, how hot do we need to get ? Below boiling point on engines with PCV for sure due to the adjustment of vapor pressure / boiling point / temperature. Also, bearing running surfaces will run hotter than regulated temp and indeed the oil passing by them.

I work with large machines that successfully keep the moisture content of the oil below 10ppm with 140f oil temps.

On my cars that on occasion we run the snot out of, I prefer to stay a bit on the cooler side for safety margin. If we run hard for a bit and see a 20 or 30 degree temp rise, I would prefer to start from 165 as opposed to 220.

This is a very interesting topic. And yes, poke a little hole in the stat to prevent air lock. An old school idea that just works. Been doing this on industrial engines for more than 20 years as well as automotive. Usually eliminates the need to burp the system.

Also,,, straight water has more thermal conductivity than ethylene glycol water mix at 50/50. if you live in a climate that will allow, consider running a higher pressure cap, straight water, corrosion inhibitor . You will need less radiator for this as heat transfer is more efficient.
 
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