Making pistons from scrap aluminum - GIF

[Frank S]

what are the small holes below the piston rings grooves for?

If you are talking about the holes below the oil ring perpendicular to the gudgeon pin, these are to allow lubrication to the piston skirt.

[desbromilow]

If you are talking about the holes below the oil ring perpendicular to the gudgeon pin, these are to allow lubrication to the piston skirt.

Frank, Yes - thank you for explaining!!!!!! I figured they were for some type of lubrication, but didn't know what they were lubricating.

thanks again,
Des