another 360/408 over heating

rod7515 said
No my cooler is mounted by brackets and bolted ain place. It's a very solid install. My first thing at this point is to see If this engine will run cool with the flex fan. If it does not then I'm going to have to tear the heads off and find what is causing this. If it does cool down then I move on to figuring out what I can do to make electric fans work.
Rod

I would not pull the heads off.
Face up to the facts.
If it will not cool while cruz'n down the road, your radiator is not large enough. I dont care what kind of fan you mount up. When you are going down the highway there is more free air going thru the radiator core than you can produce with any fan.
The radiator is the key to the entire cooling system. If the radiator is not up to the task it does not matter what you do with the rest of the system it will not work.
I have been down this road before many times over the past 45 years.
I almost got stumped once when I had a Milodon hi-flow water pump that the impeller was slipping on the shaft and the engine did not see enough flow.
Go back to the basics and you will find your issue, there may be more than one.
Good luck