Hey guys I just brought a set of GMPP racing hyd roller lifters and they're suppose to be good to 8500 rpm, the question I have is what's the max safe valvespring seat & open pressure which should be run with these?

 

Don't know that any specific numbers have ever been posted. I would guess that they'll hold up to whatever spring pressures are required to not have valve float at 8500.

 

What are you trying to accomplish? You'll need one hell of a valvetrain to approach those kinds of RPMs, and even then it won't be fun doing it without a solid roller.

 

I'm building an all forged na 383 with ported heads & intake with a custom hyd roller cam, I have no intention of trying to spin to 8500 maybe 7000 but since they use light weight parts to achieve that rpm I would normally run 150# seat pressure.

 

FWIW: We are using them on my buddy's MS4 Heads and cam combo.. He's using the PRC Dual springs.. These are the LS7 Lifter's we're talking about right?

 

No actually I have the Racing version of the lifters as used by Caddilac in the CTSV road racing cars, they are slightly different from the LS7's from what I've read. I'm putting them in my LT1 stroker since I need new lifters anyway.

 

They should be fine for something like that.

I'd use the Morel if you're doing anything too crazy.

Mike