Hi Everett, I'm using aftermarket gauges. Doesn't look like I have the space for an electric fan, even with the stock radiator. It's ok, I've had the car for 30 years and only have had a problem the last 5 or so. I'm sure I'll get it worked out.
The one thing that no-one has mentioned is pulley ratio. If overheating at idle and cooling with some air flow is the problem then a little more speed at idle may help. Over driving the water pump by a ratio of 1.25 to 1.35 seems to be recommended. I don't think that is the answer for a drag car, but i don't think that it would be a problem in a street car. Check pulley size, see what you have.
That is genius. I'm still not sure which way I'm going with this, but your insight is awesome. Thank you! The one thing I've noticed, and maybe I'm wrong, but I think a lot of replies are geared towards a built v8. Hell, even a stock v8. I'm running a bone stock 250 with no air and a c4. It's not a hotrod and doesn't get driven like one. I'm also pretty sure that over heating was a common occurrence for many drivers in the early 70s. We have speed limits that are much higher and we sure have more traffic. So its no wonder I can't keep the temp down in certain situations. I just picked up my stock radiator from the shop and may put it back in with the shroud and fan from a 76 250 with AC. Everything being ok, it should operate just fine. Just Fyi, I was running the stock radiator and that shroud previously, just with a 7 blade flex fan. The radiator had a little blockage in it but not horrible. That may have accounted for the temp increase at idle. The 7 blade fan coupled with a shroud may have made a wall that air could not pass through at high speeds. The stock 5 blade fan may resolve that. Fingers crossed.
These cars should run 65-75 mph with no issues. Till the nationally mandated 55 limit in Nov '73, speed limit on most interstates was 65-75 mph(no limit in some western states). Was 70 here in Chesapeake, Norf & Va Beach. Only within last few years has Chesp raised from 55 to 60(eastern terminus of I-64). It's still only 55 mph in Norf & Va Beach. On rural VA i-states it's 65-70 mph
Could the issue be the water pump? I had a v8 years ago were the impeller was nearly rusted away from years of abuse and neglect. It had a sweet spot for cruising, but at idle and at speed it was almost worthless.
Copied from here. https://extension.psu.edu/fuel-ethanol-hero-or-villain Some people have reported engines overheating when ethanol blends are used, suggesting that ethanol burns "hotter." This is a bit mysterious since ethanol contains less energy per unit volume than gasoline, and the flame temperature of ethanol is more than 40°C cooler than gasoline. The most likely explanation is related to the air/fuel ratio. Most engines are designed to run with an excess of fuel relative to the amount of air (a "rich" mixture); experience has shown that this leads to higher power output and cooler engine temperatures. When ethanol blends are used, newer engines are equipped with sensors to adjust the air/fuel ratio automatically. Older vehicles and small engines may not be equipped to do this, resulting in a "leaner" burn that may increase engine temperatures and/or reduce engine power. A simple adjustment to the fuel system to "richen" the mixture can often fix this problem.
Hey Don: Those ' flex-fans' have been know to ' come apart ' .. Lost a good friend here in Florida when he was winging the throttle on his stock 302 - Blades departed from the housing .. and struck my friend in the neck .. Lost his life ..Bled out before they could get him help. I have a new one hanging on the wall that will NEVER be used.. It's just a reminder to anyone entering my shop. Just my two cents. Cometized (Chip)
Exactly right, Tom. Ethanol runs cooler when.. IF.. AFR is corrected for its use but actually runs hotter when not corrected because it causes a leanout issue to occur. Can actually overheat and pound out seats or even sink/recess the exhaust valves. These old engines induction hardened seats are no match for that type of abuse over the longer term. Don't ask how I know this. lol Don, with all the extra advance you're now running it can create a situation where the carb is beginning to lean out the AFR at those cruise speeds/rpm's. As I recall from our PM's you may be upwards of 40° in total timing now which would normally be just fine under light throttle angles but when combined with a factory fuel curve designed for much less ignition timing and non-ethanol fuel blends may be causing a leanout, and therefore building more heat in those situations. They don't always detonate during leanout either and may just push more heat into the cooling system. As I already mentioned, to keep your base timing up where you like it now(IIRC.. around 14°?), it may be beneficial to limit the mechanical advance sweep by slipping a rubber tube over the advance slots limiter/bumper. The thicker the tubing the better as it will shorten up the mechanical advance and then allow you to run even more base timing without fear for over advancing at highway cruise speeds. I'd also consider upping main jet sizing by 1-2 sizes to help compensate for all the extra ignition advance and ethanol blends natural tendency to lean out AFR.. sometimes pushing past stoich's 14.7:1 and into the 15's. As for the pulley ratio's on these cars being insufficient.. Ford already overcompensated with an overdriven setup given that the stock crank pulley is larger than the waterpumps to begin with. Adding more overdrive ratio will only serve to act as a bandaid for some other underlying issue and add more parasitic loss. If you fix the underlying cause then no reinvention of that particular wheel should ever be required. Good luck with it.
I knew we'd hear about the A/F ratio but I was too lazy to explain it. Basically if ratio is now too lean, it was prior, just not as obvious.
