Quote:
Originally Posted by raceman14
Mike,
Most folks think once they are pumped up they stay that way but after many hours on the spin-tron, we learned they bleed pretty bad at high rpms. Most of the work was done for GM 604 Oval track crate engines but the theory applies to any hydraulic lifter.
It is a delicate balance kind like balancing a see-saw with the spring pressure on one end and the hydraulic lifter on the other. I can tell you that valvetrain stability is worth 10-20% RWHP increase on hydraulic lifter engine.
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I have a few questions concerning what you found.
So according to your tests the issue is bleed down instead of pumping up?
Can this be avoided by limiting lifter plunger travel? I'd assume as the spring loses control of the valve train, so the lifter is unable to follow the cam, pump-up is still possible?