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What is the "normal" operating temperature?

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I upped the thermostat on my BN1 from 160 to 180 because on cool days at highway speeds the temperature would usually be about 160, and as I understand it engine wear goes up and efficiency down at low operating temps. And while I agree with Dave's point that a lower thermostat will essentially give more of a "cushion" in stop-and-go traffic, in practice those 10 or 15 degrees disappear pretty quickly once things start to heat up. On my car at least, a HD core took care of overheating at high speeds, but the auxiliary electric fan mounted in front of the radiator is a must when stuck in traffic. Even still, I sometimes experience very rough running once the fuel in the lines and bowls begins to vaporize. Maybe someone has come up with an auxiliary fuel system cooling system?
 
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but the auxiliary electric fan mounted in front of the radiator is a must when stuck in traffic. Even still, I sometimes experience very rough running once the fuel in the lines and bowls begins to vaporize. Maybe someone has come up with an auxiliary fuel system cooling system?

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A couple of points:
An electric fan mounted in front of the radiator is about 40% less efficient than when mounted behind the radiator. The fan motor blocks off air flow. An electric fan that is sufficient by itself will draw about 100 amps.

Your DW fan appears to have much less air moving capability than the six blade steel flex fan that I am using. This fan has staggered blade spacing to help quiet it. There is no substitute for a "good" engine driven fan in stop & go driving.

A side benefit of a good fan is that it keeps the carbs cooler when idling. The air temp coming out of the radiator helps considerably to cool the carbs. It is only about 8 to 10 degrees above ambient temperature. I have never had a carb boiling problem.

With a little difficulty, you can fabricate a heat shield to go between the header & carbs. Norman Nock has published a pattern for such a heat shield. With a little modification it should work with your header.

Lastly, the fuel system could be set up to recirculate the fuel from carb to fuel tank via an additional return line. A tap at the rear carb connection with about a 1/16" orifice would suffice. All fuel vapor & hot fuel would be pumped out the return & back to the tank. This means that the supply line is always filled with cool fuel. It also means that the pump will run continuously & you might need more pump capacity. This trick has been used many times & many cars had this type of system factory installed.
D
 
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and as I understand it engine wear goes up and efficiency down at low operating temps.

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I have just started to question "conventional wisdom" that engines should operate at 190 to 220 degrees temperature. If so, a couple of manufacturere are not following this wisdom.

After recently acquiring an infrared thermo gun, I've checked the actual engine outlet to radiator temperatures. The gun has been checked against a lab standard & appears to be pretty accurate.

On my daily driver, V6, Japanese origin, year 2000, on a 100 degree day, after extended idling with AC on full, the temp was 170 to 175 degrees, car temp gage was in the middle. It appears that the thermostat is set to regulate at around 170 to 175.

On my RV, year 1999, Ford V10 engine, under the same conditions, outlet temp varied from 175 to 180 degrees. Gage near the center again. Under heavy uphill pulling conditions, the gage never gets any higher than this.

The 1984 Ranger V6, with same conditions & AC on, runs at 170 to 176. This truck has never had the coolant or hoses changed.

It appears that at least two manufacturers are not going by the 190 to 220 "rules". I also wonder if our old design engines are really up to the new temperature "standards". In spite of my previous beliefs, I'm beginning to think that 160 is adequate for our old engines & maybe better for them. I can always change my mind, can't I? Both of these engines have aluminum heads which may or may not explain the lower than expected thermostat settings. Opinions solicited.
D
 
"I can always change my mind, can't I?"

Not after I act upon what you say Dave!
 
I had an old Datsun 280Z that had a thermo fan clutch. When the engine was cold the clutch let the fan blades "slip" and not spin at full speed. When the engine was hot, the clutch would lock and the fan would spin at engine speed. To me that seemed like the best of both worlds. With a cold engine and at highway speeds, the fan wouldn't rob as much horsepower, but would lock in full when needed. Anyone ever heard of a fan clutch fitted to a Healey?
 
A fan clutch is not a bad idea, but I don't think there is room between the water pump & radiator to fit it in. The benefits would be a little less noise & a two to four horsepower increase when the engine is cool.
D
 
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