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.
|