Edelbrock Heads And Aluminum Manifold Upgrade

The Edelbrock springs measure 120lbs closed and 260lbs open (.272" cam, 1.6 ratio rockers gives us .435" of lift with my OEM cam). My old springs in my old heads measured 75lbs closed (at 1.700"). Neither the old springs or the new OEM springs measure as low as the specification as stated in the manual (76-84lbs at 1.620" and 180-194 at 1.270"). And the test dimensions in the manual (1.620" and 1.270") do not match the actual open and closed dimensions of the springs. The actual dimensions on my old OEM heads are 1.700 and 1.265. The numbers in the manual would only give us .350" of lift not the .435" that I measured with my cam. It is all so confusing! Fortunately, at low speeds, I do not think it really matters all that much.