valve float
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Joined: Dec 2010
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From: southern Alberta Canada
I used the Wikipedia reference and just because it's on Wikipedia doesn't make it wrong ... Valve Float, Valve Loft and Valve Bounce .... Three Different Scenarios!
Valve Float is an adverse condition which occurs when the poppet valves on an internal combustion engine valvetrain do not remain in contact with the camshaft lobe during the valve closure phase of the cam lobe profile. This reduces engine efficiency and performance and potentially increases engine emissions.
Valve Loft is intentionally using a controlled valve float to increase lift and duration of the valve open cycle. In some motorsports there are rules that limit camshaft lift; therefore, provoking this type of exploitation. Properly optimizing the system avoids undue stresses to the camshaft lobes and tappets.
Valve Bounce is a related condition where the valve does not stay seated, due to the combined effects of the valve's inertia and resonance of metallic valve springs that reduce the closing force, and allow the valve to re-open partially.
Valve Float is an adverse condition which occurs when the poppet valves on an internal combustion engine valvetrain do not remain in contact with the camshaft lobe during the valve closure phase of the cam lobe profile. This reduces engine efficiency and performance and potentially increases engine emissions.
Valve Loft is intentionally using a controlled valve float to increase lift and duration of the valve open cycle. In some motorsports there are rules that limit camshaft lift; therefore, provoking this type of exploitation. Properly optimizing the system avoids undue stresses to the camshaft lobes and tappets.
Valve Bounce is a related condition where the valve does not stay seated, due to the combined effects of the valve's inertia and resonance of metallic valve springs that reduce the closing force, and allow the valve to re-open partially.
To the best of my knowledge the cam doesn't touch the valve directly.... and ya floating valves are caused by the hydraullic lifters and or weak valve springs at high rpm's and no matter what causes it it aint good for the engine. I believe most evo's have factory rev limiters that will kick in b4 valve float
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