[flatjack9]

Originally Posted by L78CHEVELLE

Just had a 1940 27,000 mile block, intake and heads professionally cleaned to remove rust and junk. Had the engine sleeves taken out and 8BA standard pistons installed. Drove the car in 70 degree weather and the car ran at 140 and would get up to 160 at idle for thirty minutes. Put in some NOS 160 thermostats and the car runs 160 all the time and goes up to 180 at idle for thirty minutes. Of the hundreds of flatheads I have owned I have never had a professional rebuilt engine that has been cleaned out. On many of the other cars I did the white vinegar deal, new radiator, modern water pumps, no thermostats, full flow thermostats, you name it I did it with various degrees of success. After a professional engine cleaning, modern pumps, and a good radiator I can understand how these cars performed when new. My over heating on the other cars was not a design problem, but a combination of many little things that had changed since the parts were new. WITH THE PROPER CARE FLAT HEAD ENGINES DO NOT OVER HEAT IN NORMAL USE!!!!!!!!!!!!!!!

Well said.