Whats it mean exactly when you "float a valve"?

[Shockwave]

Is it the valve losing contact with the cam lobe due to the high RPM, such that the valve isnt seated but still travelling when it shouldnt be?

 

[Ornery]

Not enough tension in the spring, so it doesn't return quick enough.

 

[Red]

do it

 

[Bulk Beef]

Originally posted by: Shockwave
Is it the valve losing contact with the cam lobe due to the high RPM, such that the valve isnt seated but still travelling when it shouldnt be?

That's about it.

 

[GalvanizedYankee]

Originally posted by: Red
do it

NASCAR guys call that lofting the valves. If the cam closing ramp has turned far enough before the valve closes, the valve will bounce on it's seat. This will cause rapid seat/valve wear. It will also encourage the valve to tulip.
Both these events will reduce running clearance to nill and leakage/overheating of the valve will result.

The valves must be accelerated/decelerated gently at the beginning and ending of valve event for it to have a long life,
even as a race motor.