273 4bbl, carb replacement?

66fs said
I'd put a carb kit in the carb you have, but first check to see if the secondaries are fully open when the pedal is on the floor.
If you only have cooling problems at idle, you are not pulling enough air. I'd recommend a factory flex fan and be done. My 273 runs fine, no shroud, but with a 3 core radiator.
I'd run champion N-10Y same as a Commando engine. Low compression 340's run the same plug as the high compression 340's. Set timing at 10 degrees to start.

Stock engine, stock heat range plugs. HP273's run n9y's and the 2 barrel engines run 14's. If you rebuild and your compression is somewhere in between then run a plug between the two.
I bet your 3 core radiator helps a bunch. Mopar undersized their radiators from what I see. There's not much room to grow with the stock radiator. I still have the stock radiator in my 66 Dart. It is a factory HD/AC radiator though. With a 4 blade fan, no issues.