I run high quality flex fans on my small blocks in my 3100s. I have between 1/2" to 3/4" clearance from the aluminum radiator on both of them. The only noise I hear is the power steering pump.
I have a shroud on one of them which sits half way inside of it. It stays at 180 degrees all of the time.
I do not have a shroud on the other one yet. I still have to put the bed on it (its being held hostage by a miserable painter) and needs glass. I may run that one for a while without a shroud to see if it runs under 200 degrees with the A/C on.

Last edited by 52Carl; 08/07/2022 4:24 AM.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission