Wow, I haven't been here in a long time! I hope everyone is still enjoying their cars. I have had cooling problems with my newish 250 for a couple of years. I am installing an aluminum radiator and want to make sure I choose a fan that will be efficient. I currently have a 7 blade flex fan. I'm concerned that it may be blocking air flow at high speeds. I can actually control my engine temp with my speed on the highway. If I go uphill or over 65 mph, the temp will climb. I have trouble on the interstate with high speed limits as I can not go that fast and not over heat. My old 200 was the same way. The 250 will also get hot if it idles too long. A busy drive thru is out of the question for me. My new radiator is a 2 row with 1" tubes. I had a shroud but I don't think I'm putting it back. I am considering using a 5 blade fan that came off of a 250 with AC. I would love to hear what you guys think.
get rid of the 7 blade flex fan...google it and read the horror stories. you need a shroud... Taurus fan swap.... JMO
If you want it to idle and not overheat, a shroud is mandatory. Blade should be approx halfway inside shroud.
Take the plunge and do a Taurus fan. After doing this, I will never run a water pump mounted fan again.
Don, where'd you finally end up with your carb and ignition tuning endeavors? Here's my take on cooling system requirements. IF the cooling system is not blocked up or malfunctioning in any way(eroded pump impeller, sticky t-stat, sludge).. the amount of heat generated by a lower powered engine being operated at idle or part throttle is WAAYYY below even these old downflow style rad's capabilities. The fan does indeed block some measurable amount of airflow when lower rpm cruising at higher speeds but lack of a shroud will easily allow the air to redistribute towards the core's outer edges and still be more than sufficient to cool the engines BTU output. Put another way.. if that cooling system could not handle the heat output on the highway or at a stoplight?.. it would spike and fully saturate the cooling systems heat shedding capacity rather quickly during spirited driving at lower road speeds when engine output/BTU's are much much higher. First thing I would do is increase fluid flow rates with a high-flow low temp 160° t-stat. Several on the market and be sure it specifically states "high-flow design". You're in Ohio.. I was born there and know for fact it ain't gettting cooler with low humidity any time soon. lol People often think a low temp t-stat will run at it's rated temp but rarely is that ever the case except in very cool weather conditions. In essence, it opens earlier and achieves a larger opening/flow passage size to improve GPM's of coolant flow at lighter throttle angles, lower speed cruising and such. The old wive's tale of water moving through the radiator too fast is completely false.. faster is ALWAYS better but you'll always reach a saturation point based on orifice sizing and numbers of twists and turns. Next would be to get the ignition timing dialed in to WHAT THE ENGINE PREFERS FOR PEAK EFFICIENCY.. not what some engineer was forced to use towards mandated smog and warranty concerns/requirements nearly 50 years ago. The thing to keep in mind is that the ignition timing directly influences the AFR.. more ignition lead leans the mixture out.. less enriches it. In fact, Fords used temp operated valves to retard timing at warmup to create extra heat which is likely the same effect and part of your entire problem here. I know this to be fact from experience and running engines without fans entirely. The faster your cruise speeds.. the cooler they run. Retune them more towards optimum and many will be amazed at how long you can sit at lights before the gauge starts alarming them. All related to how much heat is being generated and transferred to the cooling system. Here's a very simple trick to show what ignition lead the engine is lacking during light cruise and how it directly affects the engines heat output. Get yourself a handheld vacuum pump and long 10' foot vac hose(duct tape works good to keep it under control at higher speeds or simply find a spot to come through the firewall and use less hose length) and connect it to your distributors vac advance pot. Cruise down the road with it hanging through the side window and give it a few pumps while maintaining neutral throttle at steady state cruise speeds. Speed doesn't necessarily matter so much but throttle angle needs to be kept close to constant before pumping but obviously best to mimic the worst case scenario you seem to be seeing here.. such as long grade climbs under higher loads and their required slightly increased throttle angles. Just play around at various light cruise speeds and you'll quickly see a developing trend. Make notes of engine rpm's and amount of vacuum applied which works best in each scenario because that's the info needed to static time the ignition with a timing light. So, say the engine runs best at 60 mph freeway cruise around 2,400 rpm with 20" on the vac pumps gauge. Hook the timing light up and rev the engine to 2,400 rpm while pumping the handheld pumps gauge to 20" and take note of the ignition timing number. Now hook the original vac line source back up to the distributors vac advance pot and run the same timing light test again at 2,400 to compare numbers. You will now see what amount of ignition timing is lacking from where the engine would prefer. With the handheld pump located in the cabin to control the vac advance diaphragm.. you're essentially creating variable ignition timing capability that can then be cross referenced towards what the ignition is actually tuned for the way it's currently calibrated. Most will be surprised at how far off from optimum it will be.. especially so if you have anywhere near the factory advance curves.. base timing and centrifugal advance curve calibration. Sorry if that's all a bit rambly and round about.. just too scatter brained and time limited to be more concise right now.. but hopefully you get the gist of it all. Good luck with it, Don! PS.. forgot to mention the reasoning for that long post on such a simple question. The fan shroud helps direct and increase airflow through more core area at idle and lower speeds and can actually impede overflow at higher speeds. So if you are only heating up at traffic lights?.. by all means get a shroud on the thing. But if, and what I framed my response around, you are heating up at highway speeds?.. you either have water movement/restriction related issues or simply have the tune too far off from optimum. And sometimes it's a cumulative affect of too many things not being just right as well. I've run many cars using these old style rads and no shrouds.. and tuning is THE most important thing to get right. High flow t-stats can help a bunch too. PSPS.. lol.. you got me thinkin' more bout tuning yours when I need to be out building mine. You can also use the vac pump to calibrate idle advance too. Give the vac advance pot about 15-20" of vac with the hand pump and see how much more off-idle torque the engine makes! It will also run cooler too. Just be sure to reset mixture screws as all that extra advance will act like higher base timing and not fall away under heavy throttle like it normally would. And you can't rev too high either since the total timing at higher rpm will go sky high. Have fun learning!
J Thank you for your reply Groberts 101. To answer YOUR question, it's always ongoing with that car. My initial timing is set around 16 degrees btc I believe. I forget what my overall timing is, but it is happy where I have it. Last year I noticed that I had my vacuum advance plugged and it actually runs better that way. I think the springs in the distributor are so light that it advances faster than the vacuum. Is it possible for the vacuum to actually retard the timing if the springs have it advanced? As for the carb, these one barrel carbs are the pits. I tried a remanufactured RBS carb that worked ok for a little while, then it quit. I went back to an old YF but it idles terrible. I have another RBS due here on Monday. Now to my cooling issue. I have a new 2 row aluminum radiator from Northern that I just installed. I had a stock rad, with a 7 blade fan and a shroud. I noticed upon pulling the old rad, that there was some blockage, looked like rust. Would not have expected that since everything was new a couple of years ago. Anyway, the new rad has 1" tubes and the openings are much bigger than stock. Even bigger than the Champion that I have in my Sprint. I'm hoping this will increase flow and reduce the risk of blockage. I tried installing a 5 blade fan that was on a 250 with AC but it was too large in diameter. Looks like the new rad is better suited for a 200 as the upper hose is moved inward a little. This is because the width of the cooling area is smaller than stock. So I put my 7 blade back on since it is a 17 inch fan. There is no way my shroud is going back on and I'm ok with that. The fan was set too far inside anyway. I read on another site that the closer the better when it comes to the distance of your fan to radiator. That is pertaining to no shroud. I am very close to the new rad, so I'm happy. I'm waiting for some distilled water to get here so I can fill it and try it out.
Don, good to see you posting again! I agree with Frank, do not reinstall that flex fan especially without a shroud. Those things are dangerous, they can come apart and fly everywhere and they don't care who or what they mangle. I corrected my cooling issues with the following two items: https://www.summitracing.com/parts/sum-g4903/overview/ https://www.summitracing.com/parts/sum-890015/reviews/ The Electric Fan Thermostat Kit doesn't have very good reviews however, mine works perfectly. That little 14" fan can move a lot of air. I installed these two items when I was running a 351W. My Comet would overheat in heavy traffic or in the staging lanes. Not good! I have maintained the same set-up with my 302 and they have been keeping things cool since 2009. I have a 185 degree thermostat rather than a 160. I used to have a 160 degree thermostat which ran too cold for our cool spring and fall temperatures here in northern Ohio. My heater would not heat the passenger compartment efficiently. Just another option.
From my experience with my 250 in my '74. The Taurus 2-speed fan is too thick to fit between the 250's longer water pump and the 250's V-8 size radiator. On a junkyard trip I got the fan shroud from a '76 Maverick 250 w/AC. I tried using a 302 7-blade fan but it hit the shroud just enough to sound like playing cards hitting bicycle spokes, but a lot louder. O another junkyard trip I found a 7-blade fan from a '75 250 w/AC and PS. This fan is about 1/16" smaller that the 302 fan but bigger than my factory non AC fan. I used an aftermarket fan spacer because out of all the fan spacers I collected through out the years were the wrong length to get the fan blades close to being half-in-half-out. I guess you can say I ended up be 2/3's in-1/3 out. I'm running a 160* 'stat because I want to start putting the fire out before it gets out of hand. On a hot day I still reach 195-205...cold days I see 180-190 according to the digital readout on the Dakota gauges. I have seen 215* sitting at a long traffic light with the AC kicking. Years ago I did play with the mechanical advance to come in sooner and played with the vacuum advance to keep spark knock/pinging at bay. I also tried a 2200 cfm (?) electric fan a few years ago but it started to over-heated before I got out of the driveway.
I had the exact fan shroud on the car before I did this. Came from a 76 250 with AC. My aftermarket 7 blade fan cleared everything just fine. Although I felt like it was a little too far inside the shroud. Backing it up a half inch would have been perfect but I have no room to go that way. I think I am going back to that set up and I will try different fans that I have and see if I can come up with something that fits. In fact, I have the 5 blade fan that came off the same car I got the shroud from. That was a light bulb moment! The ks for the spark!
You could try some Water Wetter to help the cooling but from my experience with it it did not help, once the car got hot it stays hot but if you can keep the car from getting hot it might be okay. When I used it it was on a 61 Falcon with a hopped up 302 and a fan without a shroud and a pusher fan in front of radiator so it had 2 bad scenarios, worked fine while moving but stop and go and staging lanes at the drag strip it was way too hot. I am like others here and say stay away from flex fans as I have had bad experience ( but on a 6 they may be okay ) and those Edlebrock foam triangular air cleaners really like to catch fire and by the time you figure it out its too late they dont go out very easy
I have also tried Water Wetter. The T stat is going to allow the temp to climb to that point regardless of what you have in there. Like you said, once it's out of control, it stays there. However, I have found that once I got moving, the temp dropped very fast back to normal.
Given a choice, if there's enough room, I would also suggest electric fan. Reason being, they pull much more air at idle speeds than any mech fan and are much safer in the respect to exploding or sticking a limb in the fan, losing/mangling that limb. Are you using OE temp gauge, or aux/aftermarket to determine overheating? Normal for engine to run warmer at idle or highway speeds.
