I guess some one of you all have a reasonable explanation, what the two plugs on each cylinder bank on my 371 engine, are for. One 21/32" and one 7/8" plug with reduce function? Heard about climate adaption or AC.

 

Those are not freeze plugs. Those are water port holes, where the water goes through.

 

As 442Harv indicated, the holes in the block you refer to are water/coolant passages. The purpose is to dissipate engine block heat.

Freeze plugs:

The function of freeze plugs is to protect the engine block in the event water inside the block should freeze. If that happened, ideally the expansion caused by the freezing water would cause the plugs to pop out relieving the pressure and preventing the block from cracking.

 

Thanks for your quotation. I do know what freeze plugs are for, but since these ones are located between cylinder bank and heads, they can't pop out. the small ones 21/32" are sealed while the 7/8" is punched for passage. I still wonder about there purpose.

 

Are you sure it's an actual steel or brass plug, or is it just a plugged up passage that needs to be cleaned out? I'ts hard to tell from the picture. Does your head, and head gasket have the same matching hole open or closed? Some engine manuals that I've seen, actually show the coolant flow patterns throughout the engine using arrows to indicate direction. My only experience is with the 394 engine. Hopefully someone with knowledge of your particular engine can clear this up for you.