Do i need to re harden a ground 3.2 crank?

[slow car]

Hi i am probably needing to fit oversize bearings to get back in spec on the mains .Do i really need to re-harden the crank?
spinning to 7.5 k 10.5:1 .
near all other engine do not harden the crank??

[Steve@Rennsport]

I always do.

[Henry Schmidt]

Heat treating is not necessary if all you do is grind the crank. If you weld and grind or the crank got overheated when a rod failed, heat treating is advised.
If you choose to heat treat, always remove the crank plugs and replace them.
If you leave aluminum plugs in the crank during the heat treat process, there is a good chance the plugs will fall out shorty after the engine develops oil pressure.
That said, we use a Plasma Nitride process after most crank work.