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Discussion Starter · #1 ·
crane says the hydrualic link bar lifters are good to ~ 6800rpm.

With any hydraulic lifter you are going to be limited to how high you can rev it before they can no longer control the valves. With hydraulic rollers the situation is worse (less rpm capability) because of the heavy weight of the lifter and the higher pressure springs used with roller cams.

Pump up is basically a situation where at high rpms the valve floats and the lifter is no longer "in contact" with the pushrod... the momentary loss of preload results in the lifter filling up and plunger coming to the top. This results in more float condition since now when the pushrod gets back in contact with the lifter, the preload is not correct. This uncontrollable situation is what breaks springs, causes valve to piston contact. The only way to subside this situation is to bring the rpms down.

So if you plan to rev beyond 6500 you will definatley get better performance from a solid roller, or a solid flat tappet.

A solid lifter cannot "pump up" so there is no float in that sense. Of course weak springs can still cause the valve to be uncontrollable, but you wont bounce pushrods.

Not sure of your plans for the 408, but revving that to beyond 6500 seems questionable as well...i don't know though the internals and your plans.
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