Didn't want to start a new thread, but thought I'd ask as here as it's pertaining to this same engine case (was on the backburner, now on the front burner!)
Here is a pic of one of the backs of the main bearings. I've not come across marks like this before. I assumed it was due to the above issues with potential current going through the case when something was welded.
Well, now I am rebuilding the engine and using a different crankshaft.
The case has been cleaned up internally and I refit a new set of Glyco main bearings, to meaure bearing clearances, use some plastigauge to get a visualy, and finally, to fit with oil and make sure crankshaft rotates freely, which it does.
When I pulled the case apart, and removed the crank and bearings, I noticed that the backs of teh NEW bearings now have very feint imprints on them, similar to the OLD bearings..
Here's is a pic of the tunnels showing their current condition.
Any input appreciated.