Running Main Bearing Inserts To use A 383 Journal Crank In a 440 Block

I am talking about a running engine. In a running engine, the heat in the brg shell gets transferred to the surrounding metal. Ever see a brg shell fall out of it's location? That is because it overheated & the steel backing lost it's 'spring'.

You might use brg inserts on a rare vintage engine because that is all that is available, but there is a reason that inserts are not used when the correct brgs are available....