Any kind of coating restricts heat transfer from a block or heads OR a radiator...
But I don’t think it’s a massive problem
As much as you and I want to believe this your statement is incorrect. I need to dig out some white papers related to cooling of hydro-static systems in large earth moving equipment done by a multi billion dollar corporation. The long and the short was painted components (including tubing etc) increase the systems cooling efficiency. Heads and blocks are no where as efficient at eliminating heat when compared to your radiator and oil cooler. Get the heat to your properly sized cooling components so they may eliminate it. I was most surprised by the recommendation to paint hydraulic tubing vs plating.
After reading that paper I wouldn't hesitate to paint aluminum heads for a more stock appearance.
Feel free to flame away!
TY
Red
