If it is "RSS" Robinson Speedshop cam out of a 'open/limited' It will likely be a 400, it was usually engraved 'RSS 400' on it. Very popular cam in the day. Robinson speedshop is no longer open. Dyno Cams ground it for them, they might give you specifications. Or I believe Hedgethpath Racing bought the rights to the cam grind, they might also give you the information. RSS did have a few other cams grinds available, so if you don't see a number you'll just have to degree it. But the 400 was most popular, and still being sold today thru Hedgepath.