My engine is overheating no ifs, ands, or buts. It's not radiant heat etc. It just slowly gets hotter and hotter if left at idle on a hot day. It doesn’t overheat if the temp is 80 degrees or less. One year at the Nationals I got caught in traffic and about burned up the engine before I could get it shut down (spark knocking, coolant overflowing, etc).

However, I am confident the incorrect water pump has been my problem all along (6 vane impeller for A/C application on a non-A/C engine). I believe when I install the correct 8 vane pump it will cool properly. It only makes sense that the engine would overheat slowly at idle with the lower volume 6 blade pump. I bought two pumps, one from NAPA and one from Year One. The year one looks to have the impeller set up for counter clock-wise rotation while the NAPA pump is set up for clock-wise rotation (they also sell the same pump for counter clock-wise rotation with an impeller that looks like the Year-One pump. For my application, I need clock-wise rotation. However, Year-One only lists this pump for the "383 - 440" application? I'm going with the NAPA pump.