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Old 01-10-2013, 05:31 PM
ap72 ap72 is offline
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Originally Posted by MouseFink View Post
Hydraulic lifter valve train must always maintain contact between the valve tip, rocker arm, push rod, lifter and camshaft lobe. That is why they call it "pre-load". If pre-load (contact) is lost due to valve float, valve bounce or lifter loft, you can have possible destruction of the engine. High lift camshafts increase the possibility of valve float if the valve springs are not strong enough to maintain the pre-load. When you reach a certain spring load, you must switch to solid lifters and self aligning rockers are designed for mild camshafts with valve lifts less than .525".

A camshaft with more than .525" valve lift require valve springs with no less than 150 lb seat pressure and 350 lb. open pressure along with full roller rocker arms. IMO, that is too high for regular production hydraulic lifters. I used Comp Cams 15850 short travel restricted oiling lifters because my Comp Cams 26918 beehive valve springs were set up at 144 lb. seat pressure at 1.750" and 330 lb. open pressure at .500" valve lift. No valve train noise and no sign of valve float at 5,500 RPM.
A hydraulic lifter is designed to always have preload- HOWEVER it does not mean it does in operation. Yes even in a bone stock application.
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