I put an aluminum Champion in my 40 a few years ago and so far it has been doing the job keeping the 350 at acceptable temps.
Temp gauge has gotten up to 200 on 90 degree days pulling a long hill but drops down after leveling off.
I am using the marginal cap that came with the radiator but think an upgrade might help keep the temp down better.
I have an electric fan and shroud that pulls air through the fins.
I read up a little on brass Vs. aluminum before buying and the trade offs seemed to balance out so decided on the aluminum partly for price and partly for bling.
I am not unhappy with the aluminum but my memory says the original four row radiator was better.
The original radiator was about 15 years old when it started leaking.
Had it rebuilt and went another five years before leaking problems and kept patching it for a while until it just wouldn't hold together any period of time so found a new three row and ran it for a couple of years.
It worked ok in winter but heated up just pulling out of the garage on a warm summer day.
I still have it boxed up on a shelf in case I need an emergency rad in the event the aluminum one takes a crap.
I would consider another aluminum when the time comes but then again my memory says the brass was better.
As usual reading these posts I am happy with the way something is set up and then someone suggest a problem and I start to worry.
Now flex on the radiator in mentioned.
The radiator on my 1970 is bolted into a U shaped piece of metal that is bolted to the front cross member and a quarter inch rod runs from the upper right hand corner to the firewall.
The mounting bracket more or less floats there.
I can't see how it can be made any less stressful.
Rubber bushings alone will not help. You will need to use a grommet type setup where the bolts holding the radiator are cushioned by the rubber. Just a thought.
