If its the frost plugs you are refering too,the convex part faces outwards,towards you as you look at the engine.This is so you can use a drift or in my case I used a socket,about 1 inch or larger with an extention inserted from the bolt end(backwards) and used as a drift to flatten it and seat the plug in the hole.So far I have not had any leaks from around my frost plugs.
Hope this helps.....good luck...Mark