08/22/2022
Posting this in hopes to clear things up. As much as we wish there was a clear cut answer, it's just not that simple.
The ever-elusive, "what's the maximum spring pressure and RPM your lifters can take", question. Seems like more and more people are racing to put the largest springs on a combination (typically more than required and IMO a band-aid for most) instead of trying to get away with the least. Regardless of my feelings on the subject, it's very common. It's also a question that is almost impossible to answer correctly with generalities about a given engine platform. There are just too many variables. Clearances, valve material/mass, valve diameter, rocker arm type and mass, spring and retainer mass, cylinder pressure and backpressure, oil type/temp/pressure, geometry changes with certain cylinder heads, and of course cam profiles. Then you get into different platforms that can change the equation completely.
Our blanket statement that covers most engines and their combinations is 250 seat/600 open (up from 565). That said, we've certainly been successful with more spring, as well as been unsuccessful with less. It's all in the details.
RPM is a different matter entirely. If you've optimized everything mentioned above for a hyd. roller, 99% of the time the engine will spin at whatever the rest of the parts selected would have allowed it to operate at anyway. In testing and customer data logs we've seen just under 10k. So, today I'd say that's the max.
