[Formulajones]

Originally Posted by grivera

Could the high spring pressures cause the bleed down issue?

I'll elaborate on that further with some experience I've had with that.
Decades ago the 454 bbc I built I used AFR heads. They spec'd the camshaft which was a hydraulic roller. They sent the heads with solid roller spring with 275 #'s on the seats!! The engine actually ran perfectly fine. The Johnson lifters did have a slight sewing machine noise but nothing harsh and hard to hear with the hood closed.
I drove and raced the car for 2 years like that. Until one day it developed a squeak. Sure enough turned out to be a wheel on one of the rollers.
In a nut shell the hydraulics worked ok but eventually it'll eat a wheel with pressures like that, and it did. I checked pressures on disassembly and found the spring problem. I reassembled with new cam, Johnson rollers and springs with 160 on the seats. It's been running fine for the last 26 years and spins to 6500 no problem.


I think when you start really pushing the spring pressure it does have an effect on reliability and the same effect on the other side of that
spectrum too. With every engine
being different there is no good answer but if 160 on the seat is good enough for a BBC to spin a hydraulic roller to 6500 I can't see a reason for needing 200 on the seats. That just sounds like it'll be harder on parts than it has to be.
Maybe other engine builders with more experience spinning heavy valve trains can comment