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There is no downside to running a 180° thermostat, it increases thermal efficiency. You should also install a coolant recovery reservoir to keep air out of the system.
160° T-stats were used when Methanol was used as antifreeze, the low temp kept it from evaporating right away. Nobody uses Methanol anymore. I run a 195° in my Y Block and it puts out good heat, the 180° not so much. Big difference. Depends where you live too - Texas or Arizona versus Montana or Maine. A lot of people would install a cooler thermostat if they lived down south. The shop manual specs by '64 for all truck engines is "opens at 185° - 192° fully open 210° to 212°", it appears to me the OEM T-stats at some point were probably a fair bit closer to the high side of the range and don't translate exactly with modern replacements. If you look at the NOS T-stats they were also large, solid brass high flow units. Don't try to get jiggy with the radiator cap pressure though. They probably used a 4 lb or maybe a 7 lb cap, do not exceed this or the radiator will likely burst.
Your choice of T-stat may impact your temp gauge reading. Based on my 55 the mid point on the gauge was around 160. I ended up adding resistors to the gauge to get 205 ad my mid point. Trial and error with a pot of almost boiling water to get it right.
Before you change anything, check the temp at the thermostat with an infrared gun and the engine fully warmed. I run 160's and actual operating temp is 190+ year-round. The thermostat rating is the opening temp, not the operating temp.
The thermostat rating is the opening temp, not the operating temp.
It's also the closing temperature. Engine will not run any colder than the nominal T-stat temperature rating once the engine temperature stabilizes. An amazing number of people never quite grok this! SAE or somebody like that published a paper years ago indicating cylinder wear rates were reduced by 50% just by going to a 180° versus 160°.
160° T-stats were used when Methanol was used as antifreeze, the low temp kept it from evaporating right away. Nobody uses Methanol anymore. I run a 195° in my Y Block and it puts out good heat, the 180° not so much. Big difference. Depends where you live too - Texas or Arizona versus Montana or Maine. A lot of people would install a cooler thermostat if they lived down south. The shop manual specs by '64 for all truck engines is "opens at 185° - 192° fully open 210° to 212°", it appears to me the OEM T-stats at some point were probably a fair bit closer to the high side of the range and don't translate exactly with modern replacements. If you look at the NOS T-stats they were also large, solid brass high flow units. Don't try to get jiggy with the radiator cap pressure though. They probably used a 4 lb or maybe a 7 lb cap, do not exceed this or the radiator will likely burst.
I will absolutely run at least a 180 and probably a 190-195 stat. I had a radiator shop in Tacoma, Wa rebuild my original rad several years ago and in addition to changing it from a 3-row core to a 4-row core, he told me to use no more than a 13psi cap because it might "pop" the upper or lower tank off! I was going to start with a 7 and maybe go to a 10 psi cap
I plan to run CAT EC-1 50/50 coolant and looking at the max pressure produced by it, even at 220 degrees, it shouldn't boil with the cap even removed.
From the following chart, you could get to nearly 250 degrees with a 10 psi cap. (and not boil) https://durathermfluids.com/pdf/tech...ling-point.pdf
I also plan to install a pressure gage on my cooling system for testing.
We have pressure gauges on our cooling systems too. What people don't realize is that there are actually two unrelated pressures in this type of cooling system. 1) The system pressure as compared to atmospheric pressure, and 2) the pressure created by the coolant pump. The system pressure in the pic is 13 psig.
We have pressure gauges on our cooling systems too. What people don't realize is that there are actually two unrelated pressures in this type of cooling system. 1) The system pressure as compared to atmospheric pressure, and 2) the pressure created by the coolant pump. The system pressure in the pic is 13 psig.
Good point the rad cap pressure may be different depending on the type of rad. Almost all older style vertical flow rads the rad cap is on the high pressure side of the rad (hot side) on many cross (lateral) flow rads the rad cap is on the low pressure side (suction side of the rad) . So with cross flow rads with the cap on the suction side of the rad the caps will generally be much lower pressure than on the high side..
The hotter you can keep the engine the more efficient it will be and the lower the cylinder wall wear will be. See below chart. So ideally you want to run the hottest T-stat you can get away with.
As stated before the temp of the T-stat is the opening temp. Full open may be 10°F or higher. Also if high flow stats are available for you application then they are the way go. High flow stats give you that extra margin of potential cooling capacity if things gets hot. See below pics of high flow and standard stats high flow on the left. For high flow stats the best are the Robershaw ones as pictured.
Flowcooler has the good Robertshaw stats for our older trucks. https://www.flowkoolerwaterpumps.com...ke=make%3Aford
The hotter you can keep the engine the more efficient it will be and the lower the cylinder wall wear will be. See below chart. So ideally you want to run the hottest T-stat you can get away with.
As stated before the temp of the T-stat is the opening temp. Full open may be 10°F or higher.
Most thermostats are not full open until much more than 10F above opening temp.
Many years ago, a member of this forum called Stant and spoke at length with one of their thermostat design engineers. See attached.
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