Is this a drain back solution or something?

[littlebuck23]

Took off the valley pan and found a rather oblonged hole.

I know very little about this motors history. Mabye a pushrod got let loose sometime?

 

[littlebuck23]

The boys over on binder buliiten have confirmed his is a rather official fix for drain back issues.

 

[Scoutboy74]

I was one of them. Only it wasn't a fix. It was done following the casting process before assembly began.

 

[Robert Kenney]

I agree with the way trever said it.

It is part of the sand casting process. The crank case sand core and lifter valley sand core are intended to meet forming a through hole. As is the case the two did not meet and metal filled the gap with what is called casting flash iron. They knock it out so oil is not trapped. I would not call it a drain back fix but normal post casting clean up. You can see many areas where these steps have been taken.

 

[dkminors]

There are a few shots of an engine with the exact same knockout drain in this thread. Also, there's a lot of learnin' to be had in the thread overall relating to the oiling system on your engine.