440 cam

You are limited by the coil bind and clearance of the valve spring retainer and the seals/guides.You need to have a dial indicator put on the head and see when the spring stops,then remove 0.075-0.100 off of that spec,this spec allows for heat expansion and clearance.But this is not the way to go about this.You need a cam kit,with proper srings and retainers and locks,plus you will need adjustable rockers and push rods.The new cam installed with out the kitmost likely will never start due to it keeping the valves open all the time,due to no adjustability,mrmopartech