Cooling water in Blocks
Some cylinder heads are notorious for cracking the valve seats due to poor heat transfer. Six cylinder Fords and three-valve Bugattis have this fault.
I am modifying my Bugatti block, which has an integral cylinder head, using a copper pipe gallery from the bottom of the block to above the valve seats position and squirting a portion of the water to the block via brass jets to where it can do the most good. This is hidden inside the block and is a bit tricky to fit.
It dawned on me that every car I have ever seen takes the coldest water from the bottom of the radiator and feeds it via a pump to the coolest part of the block, ie the lowest level, usually by some type of spreader manifold.
This does not make sense as the cylinder walls are much cooler at the bottom due mainly to adiabatic expansion of the gases and some heat loss through the cylinder walls to the coolant, but the maximum cooling is required at the top.
Bill had also noticed this aberration and told me that the latest F1 Ferrari fed the coolest water to the cylinder head. Clever Italians engineers.