My take on the oiling system crossover tube for the small block

I checked tonight after work on the #3 main as it drilled harder than #4, #2 and the original #1 I had drilled.
I thought something was suspicious. LOL
It basically did the same thing as the 2nd time I drilled #1 up to the other side galley.

I got some safety wire and started fishing around with a small hook on the end to feel the passages.
#2 and #4 felt as they should smooth and then dropping into the oil galley.

#3, had a little hiccup and eventually I was able to get the wire to come out of a top hole in the head.
Bummer.

#1 would have been fine with the set screw at the main saddle and the expansion plugs pushed back in deeper to prevent oil getting into the coolant passages.

#3 I have no way to get back in there.

Maybe this is why some books say to use one size smaller than 5/16 to drill the feeds to the mains.
Amazing the drill did not follow the previous hole.
If I was trying to do that I could have never made it happen.

I do have another LA 360 block I can use.
I wonder if filling this one solid and using a Mac truck oil cooler would work??
Man that is a bummer. Can you share with us what drill speed you were using, etc? We did 5/16" bits through the 4 passenger side oil passages, so it can be done. But we:
(Just what you need to hear after the fact LOL)

IMHO, I was reading your earlier posts and was going to comment that I was a bit skeptical that a simple plug was going to seal the coolant from getting into the oil gallery.... unless you put some sort of sealer on it. Seems like a dry plug might seep some coolant.

Seems like a good plan is to figure out if you are going to do these mods up-front and do them first thing... in case something goes awry...