Super, super helpful context; thanks!MadBill wrote: ↑Thu Jan 11, 2018 8:59 pm*Just to be clear, should add: "...with as much over-rev capability as you think necessary." E.g., an automatic-equipped car with a rev-limiter has less over-rev potential than a manual without. That said, some reasons for spring commonality:NewbVetteGuy wrote: ↑Wed Jan 03, 2018 3:15 pm I have another dumb question: My cam's exhaust lobe has slightly less lobe lift and slightly more duration than my intake lobe; it also should have a lighter weight valve as it's 1.6" vs. 2.02", so shouldn't I be using springs with less seat and open pressure on the exhaust valves than the intake valves?
Why do I almost always see the same springs on intake and exhaust when the goal is to use the lightest spring that can adequately control the weight for your desired max rpm?*
Adam
o Convenience; can't mix them up.
o The exhaust springs pick up more engine heat, reducing their performance and life. (If you line up all the springs from a high-mileage engine, the exhausts' free length is usually less.)
o Since the exhaust valve is closing as the piston arrives, it is the one that gets tagged if it's not following the dictates of the lobe, so a little more spring force is cheap insurance.
Adam