Originally Posted By ahy
Generally cool when rolling and hot at a stop is air flow related.


Pay attention folks, this is a key point.

If you have overheating issues at idle the problem is not likely water flow related.

Heat generated is a factor of HP, period. You might only have 60 more cubes, but how many more HP than the "cooled just fine 440"?

I had a 413 that ran just fine temp wise, then I rebuilt it and warmed it up some. It would overheat at idle and low road speeds, but before the rebuild it didn't do that. I did a bunch of stuff to fix it, even put in a bigger radiator. Nothing helped till I got a shroud then no more issues.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.