318/360 heads,with thumper cam

So i wiped the pistons off a little bitter,and cleaned the greas off them,idk if my cam is to big or what??,every single piston has signs of both valves hitting on them,all have signs,does this mean my thumper has to much lift? Its .486" intake, and .473" on exhaust,im using stock rockers,how much lift do 360 heads allow before the valves start hitting the pistons?thanks..