Edelbrock Heads And Aluminum Manifold Upgrade

The OEM replacement springs that I used are Federal Mogul Sealed Power VS721. There is wide variation from spring to spring. So I tested each one and sorted the springs by tension. I also checked them for bind height. Since I am using rotators I need to be sure I have plenty of clearance when the valves are open. All exceeded the OEM spec range by anywhere from 1 to 20lbs. The bind height varied quite a bit too. 1.000" on the low end and 1.087 on the high end. So much for quality.