I am starting to put back together a bent rod engine. It has been fully machined and now has forged pistons and rods (and all the machining needed to get her going again).

I noticed that there is a strange hole near at the far corner of the bottom of the block (near the crank). The shape of this hole looks to me like a crack or rust opening. I don't see it as something that would cause any catastrophic issue, as it is just a mounting hole, nothing vital. But it still has me worried.

1) Is this normal or is my assumptions correct that this is an abnormal hole/crack.

2) If it is abnormal should I:
a) Leave it alone. I repainted it with engine enamel so that should stop any rust or maybe further issues
b) Fill it with JB weld or other fix approach?
c) Other?

 

Perfectly normal on BPs.

 

I was expecting to see nsfw content