[getmygoat]

I put an aluminum rodney red in my overheating '69 GTO in around 2003 - it made the car run cooler..

In around 2006 I put a recored brass/copper? radiator in my 70 GTO (cost about the same - around $400).. but ordered the higher performance version that had denser fins per inch... Rebuilt motor was overheating badly prior to the recore - after the recore - beautiful temps all summer long in San Diego - no doubt this high performance copper/brass recore can handle it.

I'm now in the "no need for aluminum" camp.... I think a lot of folks fail to recognize that radiator performance degrades with age... People are wondering why their cars overheat, and even though their radiator isn't leaking, its not cooling like it did when it was new.

I spent months chasing timing, impeller clearances, thermostat temps, etc - it all seemed to just nip at the heals of the problem. Replaced the radiator and BAM!, temps dropped 30 degrees on the highway.

Regarding this 389/455 issue, its very possible that the current radiator's performance is degraded, but its still adequate to cool the 389. However, another 15% engine displacement is enough to tip things over... All the engine has to do is generate 1% more heat than the radiator can reject, and that 1% quickly builds up. - Or is could be something else -

My two cents