Spring Pressures. Solid roller lifter on a hyd roller cam.
Its all about the grind.
Some dont need 675-700+ open, some do.
Every cam company under the sun have their own required spring pressures to live according to them. Would love to hear from them as well... that would be interesting ...but look in your catalogs at the rec springs for fun.
Here the fact. Years ago, it was criminal to say a cam needed more spring load. They were called parts breakers and they got a bad reputation.
The issue was the same. It takes spring load to keep all that together. I almost never car what the cam grinder calls for on springs. Almost never. I've seen more broken **** from junk springs with the wrong rate and/or not enough pressure to know.
I send out hydraulic rollers with solid lifters at no less that 220 on the seat, and would rather see 240.
Any solid roller doesn't get less than 300 on the seat. Ever. That means you have to have your **** together. You can't run 3/8 pushrods. You can't have rocker gear that was junk in 1990. You have to use quality locks and retainers.
What the cam grinders says means little to me. I remember being at a divisional race and a friend of my dad had his Comp car there. Went over to meet him as I never met him. He was lashing the valves. Had three different color rockers on there.
So I asked him why the different rockers. He said when the springs go below 300 pound on the seat, it kills a rocker. So we try and go in at 325/330 and shim them once. Once they hit 310-315 I replace the spring.
At that time, Edelbrock was the ONLY one selling springs with that rate and load. Soon, a company called Addco came along and you could buy springs that went in at 2.00 with 300 on the seat and 2.100 at 320. That had to be the very late 1980's or maybe, 1990.
So you are only almost 30 years behind.
