Valvesprings for the Magnum
Nice blog post with lots of relevant info. I’ve only tested one stock spring on a 5.9 of unknown mileage. The engine was pretty clean inside and if I had to guess lived a easy life and I would estimate less than 100k miles. The stock spring was 95 at 1.650 on the seat and 190 open at .485. Pretty weak stock spring and barely adequate for a 4500rpm truck engine with a very mild stock cam profile. As said above ANY cam change needs to be combined with an upgrade in the spring department.
