[Jay S]

Originally Posted by grivera

What is the safe high limit for spring pressure with the CC Evolution HRs?

It depends how aggressive the profile is. The body is rated for up to 500 lbs. But they won’t make it anywhere close to 500 lbs in a Pontiac and perform well. I’d say 150lbs seat an 400 open with .650ish lift is safe with the Bulter XR cam and evo’s. The OF1 could probably run about 165 lbs and 430 open with .650 ish lift and go a few hundred more RPMs than the more aggressive XR.

The Johnson PR’s (which are also reboxed as some Crowers and Isky’s) have a bigger diameter plunger and can handle aggressive cams, but the bodies are not as heavy as the evolutions and they do not have pin oiling.. The Isky HPx are rated for 535 lbs and 185 lbs seat at 7500 RPM. Some Morel short travels are up there also, but they are more of a race lifter an do not last well on the street.

[grivera]

Originally Posted by Jay S

It depends how aggressive the profile is. The body is rated for up to 500 lbs. But they won’t make it anywhere close to 500 lbs in a Pontiac and perform well. I’d say 150lbs seat an 400 open with .650ish lift is safe with the Bulter XR cam and evo’s. The OF1 could probably run about 165 lbs and 430 open with .650 ish lift and go a few hundred more RPMs than the more aggressive XR.

Good to hear. My KREs have PAC 1914 springs:
155lbs @ 1.835, 385 lbs @ 1.200

With the Harland Sharp 1.65 rockers, my lift is .627/.632