The electric fan and shroud is the one that came on the radiator. I will try the restrictor, what diameter? The comment about the factory temperature and thermostat makes sense and makes me feel like an idiot! I also am borrowing my son's inflated temp tool to verify the temperature. The engine is slammed back against the firewall, so to use an engine driven fan will require a long shroud which is on my list. Thanks for all your help. I will post pictures later today
I’ve only seen them in a lot with the 3 sizes I posted. It’s cheap, try the largest first and see what happens. a fan and shroud will do wonders. get a bottle of water wetter also, cheap and it works. Let us know how you make out
You are correct. Below is something I've put in a couple previous posts regarding the "coolant moving too fast" myth: The "coolant moving too fast through the system to cool" theory has been debated at length on this site, and science has proved it wrong. For those that cling tenaciously to myths, I am going to take one last crack at forever dispelling the Granddaddy of them all when it comes to cooling systems. The myth is stated as either: Coolant can be pumped too fast through the engine for it to absorb enough heat, or Coolant can be pumped too fast through the radiator for it to cool properly, or Cooling can be improved by slowing the flow of coolant through the radiator so it cools more completely. NONE of these is true. The simple truth is that higher coolant flow will ALWAYS result in higher heat transfer and improved cooling system performance. The reason the myth is so persistent, is that: a) without knowledge of fluid dynamics and laws of thermal conduction it does make a kind of intuitive sense and b) it is based on a tiny kernel of truth, but that kernel of truth does not explain the overall system behaviour and so, interpreted out of context, leads to a completely erroneous conclusion. So, let's start with the tiny nugget of truth. If you had a sealed radiator (no flow) full of hot coolant, and subjected that radiator to airflow, yes, the longer you left the coolant in the radiator, the more it would cool. However, if you were to plot that cooling over time, you would find that the RATE at which the cooling takes place is an exponential curve that decreases with the temperature difference between the hot coolant and the air. Put another way - when the temperature difference (delta-T) between the hot coolant and the airflow is large, heat transfer (cooling) initially takes place very, very quickly (almost instantaneously). But as that happens, and the coolant cools, the delta-T becomes less, and the RATE at which further cooling happens gets less and less until the point where the coolant and air are almost the same temperature and continued cooling takes a very long time. This is Newton's law of cooling. To illustrate this lets look at a "quenching steel in a bucket" analogy. A good example of this law can be seen when quenching a red-hot piece of steel in a bucket of water. At first, the temperature difference (delta-T) between the red-hot steel and the water is huge - therefore the initial heat transfer occurs at a great rate - the steel initially cools very fast - almost instantaneously. However, after this initial cooling, the delta-T is much smaller, so the remaining cooling occurs much more slowly. If you removed the steel after a second or two - it has cooled a lot - but it will still be warm. To continue cooling the steel to the temp. of the water, you have to leave it in there quite a bit longer - because as it cools - the rate of cooling continually decreases as well. In short - initial cooling is fast, but subsequent cooling occurs more and more slowly until cooling that last little bit takes a long time. So what does this mean? Basically it means, the longer the coolant stays in the radiator, the less efficient the cooling that takes place is - to the point that the rate of cooling is so slow as to be detrimental to overall system cooling. Better to dump the big load of heat right away and go back quickly for another load than hang about waiting for a last little bit of insignificant cooling to happen.
Ebbsspeed, great post. Unfortunately even after your great dissertation, the MYTH will continue to live on forever. As soon as you quit typing the conflicting rhetoric immediately arrived. Theres no sense in refuting it. I've resigned myself that we will see the MYTH posted whenever an overheating issue is posted. No sense wasting our time.
One of my pet peeves, people that don't read an entire thread before posting. If I can educate just one I'm happy.
There is a Cleveland-specific thermostat. It is designed to be used with an OEM water bypass plate. Many Cleveland heat issues can be traced back to the wrong thermostat, and/or a missing bypass plate. Those two must both be correct. I have been using these, in lieu of the Robertshaw 333, which I can rarely find. https://www.tmeyerinc.com/product/high-flo-thermostat/
I run my Falcon at 230ºF, all day long. It pushes no coolant out. I would put a thermostat in it, with a bypass plate, as designed, if just to stabilize the operating temperature.
Everything I'm reading about 351C is saying without the proper thermostat, a portion of your coolant is getting bypassed without ever cycling through the engine. Maybe I was wrong about why the lack of a thermostat is the issue, but I still think it's the issue.
Good luck getting that to stick. I am currently working in thermal management, utilizing liquid cooling for onboard supercomputer clusters. Like literally exactly today, on my bench, in a Level 5 secure R&D lab, working on prototype liquid-to-liquid heat exchangers. I could drag out all of the data proving that you are exactly right, but then some sensitive soul would express offense at me being a "know-it-all-engineer". Some folks feel more secure when they never have to change their minds.
I ran a 351C for many years, initial with an original 38 Ford radiator, 7 lb cap, always ran a little hot for me at around the 200F around town but ok at 180-185 on the open road. fixed this by going for a 4 row radiator and the largest physical size I could fit in, with modernish top and bottom tanks, put a 15 lb cap with large 16" thermo fan and 180 thermostat. for every lb of pressure, the boiling point is raised by 3 degrees, so a 15 lb cap will add 45 degrees to the boiling point, so BP would be 257, if you are at 200 idling on a 90 day and you are not losing water you are OK. Clevelands are not like a 283 Chev where often they won't get over 180 at idle with no fan.
it sounds like all is fine at speed, it just runs a little hot at idle, we all know that is telling us you need more air flow. Try better fan, fan shroud, bigger fan coverage. Why not use the stock 351 fan? is it not centered in the radiator? With a mechanical fan that is somewhat centered you can get 100% radiator coverage. You say you have a puller fan, the 351 mechanical fan won't fit?
Run a 160 thermostat and put a clutch fan on and get rid of the toy fan... Thunderbirds have some of the best looking engine bays with that cool hood and those valve covers why make it ugly with that cheap fan. Put a nice looking clutch fan in there..
why did my ride always run hot without the thermostat? not debating the science, just want to know why it didn't run hot with it.
found this answer on a corvette forum discussing this. What say you engineer people? this is a response to a question on running a car without a t-stat. "contrary to thermodynamic principles and not true...higher flow rate will INCREASE heat transfer in both engine and radiator, lowering temps. perp is actually the 'impeller' found in most auto water pumps, designed to function with system HEAD (resistance) that includes a t-stat...deletion of t-stat often causes pump operation to 'go off the curve', impeller 'cavitates' and flow rate drops substantially...if t-stat is deleted, install a 'restrictor' orifice (basically just a flat washer, check your local circle track parts vendor) to 'stay on the pump curve', also GM Perf Parts 'had' (still ?) a cast impeller in 'std' rotation for ~$8 with better 'curve' ...for more detailed explanation, giggle 'pump curves' or N.P.S.H. (Net Positive Suction Head) or talk to any HVAC engineer"
Ok, I'm gonna offer a suggestion for the original question............then I'm gonna tackle the "myth" that I believe. One thing I saw somewhere is that when running an electric fan, an engine at idle may not be providing sufficient current to turn the fan(s) along with the other electrical devices it may be supplying.....A/C, lights,etc. OK, now for the myth. I think basically what Ebbspeed said is correct, but the thing that I always felt got left out of the discussion was the amount of water available. If there is an unlimited supply of water at hand at a predetermined temperature and its flowing past a hot object.......it cannot flow too fast as long as cavitation isn't present. It takes a specific amount of time and surface area for btu's to transfer from any solid to any fluid. If you have that unlimited supply at the correct temperature, then time becomes irrelevant because the correct temperature is always present and speed doesn't matter. If on the other hand you have a limited supply of coolant (as in a system) the coolant must both absorb heat from one source and give that same heat up to another medium (air). Water is more efficient than air at transferring heat. Lets say my engine transfers 100 btus into my coolant in 60 seconds and that the speed of the coolant flow doesn't matter. Now since I have a limited amount of coolant in the system and air isn't as efficient at removing heat, my radiator is only able to give up 75 btus to the air. Now the crux here is the time factor. The water is moving thru the radiator too fast to completely give up 100btus. Its not that coolant can't be made to move even faster thru the system and maintain the same 100/75 ratio (Yes I know it won't stay exactly 100/75), but that while the coolant is contibuously absorbing 100.......the radiator CAN'T transfer the 100 BTUs to the air in the same amount of time. Therefore the water is passing thru the radiator too quickly but passing thru the engine satisfactorily. The "speed thru the radiator is too fast"......AND/OR the radiator is not sized correctly. A larger radiator provides more area to pass the btus to the air......which effectively increases the time the coolant is exposed to air. So it doesn't need to slow the coolant down if its large enough to completely transfer 100 BTUs in the same amount of time that the engine can give up 100 BTUs. Its semantics........No coolant can't flow too fast to pick up the heat, but yes it can flow too quickly to give up the heat to the air. Its not the speed of the coolant, but the speed of the coolant in relation to the area. Increasing area is essentially the same as increasing the time OR lowering the speed so it speends more time in the radiator. I think its incorrect to only say coolant can't move too fast because you have to also consider the components abilty to provide what you need at that coolant volume and speed. One only has to touch a hot part to see the effects of time and area. Swipe your finger quickly against a part you just welded and see if it has cooled. Then forget you just welded it and pick it up with your whole hand. Time and area will develop a whole new frame of reference. Anyway, hopefully no hard feelings here, but thats how I think things work. Coolant can't flow too fast as long as you have an infinite supply at the correct temperature. Coolant can flow too fast to dissipate heat when you have a limited supply and the components aren't sized properly. So its often referred to as "speed" when its actually "time to pass thru an area" which is commonly referred to as "speed".
You forgot something very important in your analogy there, if you slow the flow rate down to keep the coolant in the radiator longer, you are also keeping it in the engine longer. If time is the issue you think it is, then the coolant will be picking up additional heat from the engine while trying to shed the heat in the radiator. You've accomplished nothing. In your example you simply have insufficient cooling capacity, and nothing you do will correct it except additional capacity.
I did some research last night after @Ebbsspeed post. A lot of conflicting information, depending on what site and what era ( new vs old cars) you read. One thing that WAS almost a constant is that a T/stat does little to help cool an engine. Where the division is , is on restricors bypasses and different was coolant can flow through an engine/ radiator cooling system to dissipate heat. I stand correct on my thoughts that I was taught and held as truth all these years. I’m going to keep researching this topic , as something as basic as a cooling system there is actually a lot going on, and I’m not 100% sold yet due to the little I did read as far as restrictions etc and time of coolant spent in the hot engine or dissipating heat in the rad.
t-stats main objective is to maintain an optimum operating temperature and for cabin heating the cooling system should be called a temperature management system but explain this, a 302 I installed in my 67 needed a t-stat. I bought a 180 stat. It ran hot. Bought a 195 and it stopped running hot.
yep the same radiator was cooling an FE and was in great shape. this same engine ran hot without the stat never an issue with the 195 stat it would overheat at idle. could be related to the flex fan. Its doesn't overheat at idle with the 195 stat and same fan. No shroud.
Another possibility is engine tuning. Running to rich/to lean, not enough advance/ to much advance. Also charging system out put and correct electric fan relay and wiring. If I remember right early 70's ford alternator only put out about 50 amps or so, depending how you have it wired it may not be operating properly. Also a possibility is fuel, modern engines running ethanol are designed in many case to run 200 plus. Here in Wisconsin I can still easily get non ethanol premium fuel and run it in all my pre 1995 cars ,trucks and motorcycles. My off topic 1994 F350 with a 460 that I still own would run hotter and use more fuel even when fairly new if I ran ethanol in it as oppose to premium . And I always run a thermostat the way the engine was designed to run it. Lots of things can come into play when dealing with old cars and motors. Believe me I have 50 years of lessons learned. Larry
The funcion of a thermostat it to warm up an engine quickly. It does nothing else. Once it reaches its factory set temperature setting it opens and remains open until the water temperature drop below its factory setting. Period.
Gman it’s job is to KEEP the engine at a specific temperature. That’s it’s main job. After it gets the engine to operating temperature. Bones
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