I just bought a pair of Ford Racing GT40 aluminum X305 heads from a dealer in USA. The stickers on the Ford Racing cardboard boxes says they are X305 (58cc) heads, but how can i really know they are? The heads have "X302" and "F3ZM" casted into them. According to the FRPP catalog X302 heads have a 64cc chamber ? Shouldn't these heads have a "X304" casting??
Boxes were unopened, so I doubt anyone switched them with other heads. Also there were no instructions included, should there not be any with this kind of parts??