I'm sure everyone who has been around old cars has heard the tale not to mess around with engines that have been bored over too much as that can cause them to overheat. In my mind, as small as it is , the amount of material removed between a .0.30 over block and say 0.60 block seems miniscule in the big picture so perhaps this may be just an old wives tale that clings to the hobby even today?

It would seem that a block with thinner walls would transfer heat into the water jackets faster and therefor run cooler? Perhaps the thin wall block actually puts heat into the water jackets too fast and the cooling system can't keep up?

The block with the thicker walls would retain heat longer as there are more metal molecules in play. To me this would be a slight negative as the heat transfer process to the water in the block would be slower vs a thin wall block.

Anyone ever have any real world experience with rebuilding an engine only to have it run hotter afterwards?

Discuss?