I made the decision to go a dual spring for a number of reasons. The low RPM’d of a diesel doesn’t mean that the spring requirements are as simple as toss a spring at it.
A diesel requires very short timing events to maintain cylinder pressure, but big .200 lift numbers needed to move air require to make power. This means high acceleration rates.
A single spring was in no way, going to address all aspects of the particular control model, I wanted to achieve. I can’t begin to tell you have much time I spent on a spintron, with different spring, both singles and duals.
The results are that if you are only looking for a seat number it’s possible to get it done with a single, but the progressiveness was not as linear as I wanted to achieve. The harmonics is a different story, and the dual springs have different harmonic frequency’s that help to cancel out each.
The only drawback was that a retainer was necessary, Titanium was my choice, it’s stronger, and lighter, it just cost more. Some people who understand little about valvetrain dynamics made statements that titanium would not hold up to the rigors of a diesel . We all got a good laugh out of that, the retainers don’t know what is on the other end of the rocker arm or valve , it’s just motion , I also have Chrome Molly retainers is stock now for those that prefer it instead
You can get these MaxSpool springs, as well as MaxSpool pushrods,
Dr Performance Warehouse
Indrustrial Injection
Pure Diesel Power