[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

[T A 70]

Originally Posted by paint guy

George, you are correct about trying to compare the performance of an older copper/brass radiator to a new aluminum one, it is apples to oranges. A controlled test might provide some interesting answers. But even though the heat dissipation properties of copper/brass are superior to aluminum, what has not been mentioned yet is the lead solder used for construction. Lead is notoriously poor for thermal conductivity, and when figured into the equation, I would GUESS would have a substantial detrimental effect. Just my $.02.

[quote=T A 70;4343966]Yes, agreed. But copper does not have the strength of aluminum therefore larger tubes and dissipates heat better by design...far superior...and no solder "hot spots"...[/quote]

No, it was mentioned...just fell on deaf ears....

[70GS455]

Now go another step. The core I have installed now between my original upper and lower tanks is still a 3 core, but called an SLK core, which is comparable to an OEM 4 core GM radiator. And it's made up in Philadelphia, PA USA. This core is copper with 3/8ths inch spacing between the tubes. Yes, I measured it. I've no idea as I did not count the number of tubes in my original OEM 3 row core, but this core has 168 tubes and too many to count extra fins.

Current parts store radiators and standard re-cores do not have sufficient tube count or fin density.

It takes a custom core like mentioned above (high-efficiency spacing, large(r) tubes) to equal OEM cooling (comparing copper-brass).

Your original OEM core will have 39 rows, with 3 tubes per row. The tubes are 1/2".

An OEM 4-row will have 156 tubes, so the SLK core 3-row has 12 more !

[3 Deuce 64]

just to report back my results, after it's all said and done the replacement clutch fan was bad. it cost me a good running motor and a month of screwing around . The 0riginal 47 year old 4 core is in and running at 190* .

[Ragtop Man]

Lead solder has no functional effect on thermal conductivity, which is the whole thrust of this thread.

Copper or aluminum, if the rest of the cooling system isn't up to the job, it won't matter WHAT type of construction your radiator is.

The two main factors are the mass of air going over the core, and the amount of fin surface area created by the core. The thermal conductivity of brass/copper -- a denser metal than aluminum -- will have some effect on how well it transfers heat to the surrounding air, but it will not be the deal breaker, all other things equal. Anything that helps drain the heat in the water into the surrounding air will help, including water-wetter, shrouds, a properly sized fan, a proper verified fan clutch, and above all the correct clearance between the plate and impeller which maintains proper water flow.

FWIW, when thirdgen F-bodies were having problems with high underhood temperatures (yes, even in the late '80s carbed engines were still having hot soak issues) the '88 or '89 Firebird switched from a smaller lightweight aluminum radiator to a larger copper-brass version, cost and mass be damned. When they did, they pretty well eliminated the warranty issues for hot running and overheating.

[Pepi]

Originally Posted by 3 Deuce 64

just to report back my results, after it's all said and done the replacement clutch fan was bad. it cost me a good running motor and a month of screwing around . The 0riginal 47 year old 4 core is in and running at 190* .

Just curious, how did you verify the clutch fan was bad?