How much nitrous for a stock piston?

I have a holley ignition with rpm window switch. The fuel pump is a mr.gasket electric 4.5-7 psi unit. None of which matters at this moment, cause I just found cracks in my cam bearings and if I'm not mistaken that's a sign of a cracked block. I am not happy.

did you see any cracks in the block?
Surely if you saw them in the bearings, you would see them in the block too without too much effort.