I successfully removed the engine and trans. from my 1956 vic for rebuild. The engine turns out to be from a 1957, a 292 and a fordomatic. when I tore the engine apart, I found that all the pistons had two rings in the center groove, what looks to be a regular ring and a very thin one, much like the thin ones in the oil groove. I have rebuilt many small blocks but never a y-block. Is this normal? Thanks