I have a 1940 olds with a 230 flathead. After driving for a bit tge temp gradually starts to climb up past 210/220 . I have an aluminum radiator with a 16" electric fan. Changed thermostat flushed system and checked circulation ibeven did a chemical test to check head gasket. Any thoughts would be appreciated.

 

What provoked installing the aluminum radiator and electric fan in the first place?

Make sure that fan is rotating correctly so it pushes air thru radiator if it's mounted between grille and radiator, or pulling if mounted between radiator and engine.

Also make sure it's properly sized for airflow. They're not all created equal. Ford Windstar and Lincoln Mark 8 fans will get the job done, assuming the car has been rewired for 12v.

 

I've seen the same problem in Pontiac flatheads too .
It was caused by the water distribution tube being rusted out .
The water distribution tube is made of sheetmetal , and is inside the block behind the water pump .
The tube is supposed to direct water toward the exhaust valve seats .
When they rust out , it upsets the water flow , causing " hot spots ' .

They can be removed by removing the water pump and radiator . They are usually a b*tch to pull out of the block .
They are available on E-Bay ;
1937-1950 OLDSMOBILE 6 CYLINDER NEW OLD STOCK WATER DISTRIBUTION TUBE | eBay

 

I will second this valid theory. The previous owner of my ‘40 eight made it clear to me that he’d replaced the tube in my car and emphasized the importance.