Trick Flow Heads: Conflicting Info on Mechanical Roller Spring Pressure

B3422w5 said
I really like the ISKY tool room springs, part number 9935, which I believe would work just fine for your application.
, I ran these on a 698/672 roller that saw 7500 every pass at the stripe, I got cam from Porter racing, he suggested these springs as well, and they were superb.
More like 245/ 590 at your spec.
650 to me seems like more than needed.
Best machine at the time checked these springs at a freshen up( 4 years of lots of racing) and they still checked fine.

Thanks. I was looking at the Isky Tool Room series after Mike Jones cams recommended them on another forum, but the 9935 is too light according to the cam grinders. At 245# seat and 490# rate, that's only 559# at 0.640".