Never said it eliminates, I said it HELPS remove contaminates. Let me ask you this, when I raised the temperature of my engine ~20°, why does my oil no longer smell like gasoline?
Ok, excuse me but please allow me to play along...
If raising the coolant temperature by 20°
HELPS remove contaminates, what is the other '
helper' that is assisting with removing the remainder of contaminants? Going even further, by comparison percentages, what percentage is the Coolant's temperature playing, and what percentage is this '
helper' playing??
This discussion is fascinating; I am a bit shocked that in almost a hundred years no one has done an extensive test program on thermostats in a Model A. Maybe some of the vendors who sell these products should chime in, or not. The Burtz folks still run a stock water pump, pls correct me if I'm wrong. Do they recommend a thermostat for their engines? Which are being generally driven more robustly, I think. Good discussion!!
In essence, there really hasn't been the need to do an extensive study. It is like saying we need a scientific study to determine what species of wood works best when rubbing two sticks together to start a fire. Of all the fires started in this country, what percentage of all those fires are actually started by rubbing two sticks together? That percentage is probably so insignificant that it is not worth the effort, likely because newer technology has evolved. The same applies to the Model-A cooling system. As stated above, the Model-A system was not an efficient design due to the style of Water Pump, and its' location. Beginning in 1937 when Ford engineers relocated the Water Pump which at that point, a Thermostat's use is/was effective.
Regarding Vendors chiming in, ...what can they tell you? Maybe something like "We sell a lot of them.", Does that validate the Thermostat's usefulness? Instead, why don't you ask a Model-A engine rebuilder, -or maybe a Model-A repair shop about their experiences with them?? Maybe ask them how many they have removed, and/or why?? Again, it could be argued that a manufacturer and/or a vendor might be more biased in making a sale however they may not have first-hand experience with them. Just my take on that.
One other thing that I feel is worth mentioning/discussing, but before I do, I consider other folks posting above as my friends, and it is not worth losing a friend over just for one of us to prove a point. So just consider what I am about to write as some food for thought based on my experiences, ...and others are equally entitled to their opinions too.
Just because coolant temperatures are raised by a certain amount (-in this scenario we will use a 20° benchmark) does not necessarily mean the oil temperatures increase by that same 20° amount. There are several reasons for this however in an effort to keep this short(er)
I will only address the biggest reason which is the physical location of the two fluids. The closest that the oil is to the coolant is in the lower portion of the Valve chamber. That is a large distance between the two for any heat transfer or heat soaking. Combustion heat rises, which that heat is transferred from the roof of the chamber into the coolant in the Cylinder Head. The other location is above the Valve chamber around the Exhaust ports. When you study the design of a Model-A Engine, 75% of the Cylinder is not cooled by water jackets because it isn't needed. The only place the oil contacts the inside of the block casting is in the lower section of the Valve chamber (-which BTW that area is not water jacketed) and in that 75% area under the Pistons where combustion heat is not quickly transferred. It is also worth noting that the design of the Model-A Oil Pan is that 4 quarts of oil generally resides in the sump where it is cooled, and approximately ½ of a quart is in the Chamber reservoir, and the remaining ½ quart is in the Dipper Tray.
Therefore, the only way to increase the Engine's oil temperatures to any significant amount high enough for it to remove the combustion byproducts and/or unburned fuel, would be to operate the Engine for a long enough period (-hours, -not minutes) where the oil temperature could exceed 200°. I refer you back to my statement above where the highest temperatures are in the water jacket area above the roof of the Combustion Chamber. This is a long, long way to the Oil Pan, and it's just not going to happen.
And, to remove water condensation in the crankcase will need to see temperatures exceeding the boiling point of water (-which is 212°) where it can be evaporated. Even if you were to install a 212° Thermostat, you could never generate enough heat transfer into the Oil for it to meet that temperature. Again, its just not going to happen.
Again, these are my experiences from being a racer, an engine rebuilder, and someone who thinks when they are bored standing over an engine being assembled. Other's mileage with this may differ!!
You are correct about big trucks using shutters. I have a couple of accessory shutters designed for the Model-A called Winterfronts that serve the same purpose.