Got my radiator back in. Runs much cooler with the new shroud. Still only in the 70s here, so no real test. Doesn’t overheat idling now, so that is a very good sign.
I think my shroud was the problem all along. My fan was completely inside the shroud I made. Folks had told me that the fan needed to be half way out of the shroud. I discounted that advice, since every car I have seen for the past 30 years had no exposed fan blades. They were all well inside the shroud.
I have looked at many newer engine driven fans on cars lately and have noticed that the fan blades are shaped very differently. I don’t understand fan design, but obviously (now) it matters. It appears to me that the fan design must match the shroud design for it to work properly as a system. Since I was using an older fan designed for the 1/2 in 1/2 out shroud, I was mismatched.
Don’t know if I could have also got a later model fan designed to be fully enclosed and solved my problem instead of switching the shroud.
Now I am running a Cold case radiator, Hayden 2947 fan clutch, 7 blade Mopar truck fan, flowkooler water pump, Milodon high flow thermostat, and upside down /6 shroud, and all seems well. Summer will tell....
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