I spent over a year trying to keep my 66 cool
I had a 289 bored 60 over, and I never could keep it cool.
I tried 4 core copper.
I tried 2 core aluminum.
Heres sumary of what I learned.
aluminum as a conductor of heat is not as good as copper.
The heat transfer though is more dependant on the surface are of the pipe used in the core than it is on the metal type.
A 2 core aluminum transfers heat better than a 4 core copper only because the diameter of the core pipe has to be kept small on copper or it will split. The aluminum core uses larger pipe becaue the aluminum can hold the stress without bursting. So the larger diameter aluminum gives the same (or more) surface area as the 4 core copper, thus it can dissipate the heat from your engine better.
Single most important lesson I learned though .. The material or number of cores is almost irrelevent compared to cutting that hole bigger and putting a 390 radiator in.
After I had spent over a year trying to keep my engine cool, had finally warped my 289 block, I spent an hour cutting the hole bigger and putting in 1968 radiator mounts and a 390 radiator.
End result is my 347 stroker now runs perfect temperature in 100 degree Texas summers.
Don't waste your time on more cores, aluminum, water wetter, all that junk, I tried it all, byte the bullet, put in a bigger radiator.
