i need to get more clearance at retainer/spring to the under side of rocker

using cc 977 spring w/740 retainer (1.460 od on spring that measures an actual 1.480, retainer is 1.400)

.640 roller , 150-seat/420-open

bought a new set of S70025K harland sharps that claim to work with springs up to 1.560

so what am i missing?

if i switch to beehive springs and retainers, what do i need for closed/open pressures?

You won't find a beehive spring to handle that lift. Beehives are all single springs due to their shape. That cam/lift will require at least a double spring to give you the pressures you need. Regardless of the spring "style" you need whatever pressures the cam manufacturer recommended.

is there a double spring that has a 450# min rate with a od of less than 1.470 ?

call pac racing springs for starters. Whatever the cam company reccomends for a spring.....ignore it when it comes to a beehive. Its totally thrown out the window.

the tapered shape promotes less mass, as well as the smaller retainer. This is why a beehive type of spring can do more with less pressure.

When you're controlling a smaller, lighter valvetrain....you just dont need as much spring. You might need a 450 rate with a conventional spring, but the numbers change with a beehive.

the spring is controlling everything, including its own mass, which is why the figures change with a beehive.

If the spring exists that you want, pac has it, as they make many of the beehive springs on the market sold by various companies.

PS...its a single spring. It doesnt last forever, and if it breaks, you dont have a second spring or a damper to catch the valve. Many folks dont like em for this reason because if they go south, the failure can be much more catastrophic. You can go lighter on the pressure, but a dual spring package is favored with a healthy cam by many folks.