overheat only over 3000 rpm

thanks for the replies, friends.

No, the 4 fans are BEHIND the radiator. I took the stock four blade fan off. The car was overheatig since its beginning, especially in stop and go traffic, that's why I went with the four fans and thermal switch, and for city traffic they work very well.

I put a double temperature thermal switch at the bottom of the radiator which activates first the TWO TOP fans at a temperatire of 180 °F and then activates the other TWO LOWER fans at the temperature of 190 °F. Thereafter I have four fans sucking air through the radiator.

I am a fanatic of engine tuning, so I tune the engine by hear, which in my opinion is the best way to do it, as the stock timing position might not be the best compared to the **** gasoline they sell today.
Of course I keep the carb at its top tune as well.
It's a weekly check all my life with this car.

Actually In the normal traffic condition the two LOWER fans seldom are activated. Besides, if driving at moderate speed on a country road even the two TOP fans switch off as the temp stays a tad below 180.

I did note some improvement after the crazy cleaning, it seems the temperature stays cooler, But I haven't had the chance to hit the highway on a hot day, as the weather here is not as hot as last month. I'll take the chance as soon as I can.
I'll keep this post updated.