This is something I'm real foggy on. Every time I ask one of my racer friends about valve springs for roller cams they start talking about the necessity to run springs with unreal seat pressures. But yet, you look at the valve springs that a Magnum uses and they aren't that radical. It has to be more than just roller versus flat tappet, more like what kind of roller profile that determines what kind of spring is necessary. Did I tell you this topic confuses me?
Well, you're in good company. Eddie lists the double spring head as being for roller cams and the single spring head for flat tappet - both don't give spring rates. The Comp Cams specs shows two springs that will work, a single and double - both with open spring pressures between 370 and 390lbs. My builder said the springs didn't need to be changed. I bought the heads assembled.
I'm going to call the builder today. The whole thing that started me down this rabbit hole was an issue of a push rod falling out from under the rocker (I have a separate thread for this). I was just being anal in going over the rest of the parts.
