Block plugs

What are the two plugs on the outside of the block for? One on each side towards the rear. Also what are the two plugs in the lifter valley towards the back? What purpose do they serve?

The plugs on the outside of the block are drains for coolant, they go into the jacket. The plugs in the valley "tower" are to plug the grillings for oil to cross over from the right to left bank of lifters.

I ask because the one coolent plug in the outside of the block, I went to remove it and I stripped it out. It turned about a 1/8 of a turn tho. How hard would it be to drill it out? Or will it be ok since it hardly moved?

I guess I had the wrong allen wrench. It fit nice and snug tho.

I have carefully drilled and retapped a few of those over the years. Not a problem if you take your time.

I usually replace them with a petcock so I can drain the block.

dkp

What size are the two plugs in the water jacket?

1/4" npt

dkp