Floating valves occur when you over rev the engine past the limit the valve spring seat pressure can handle. In other words...

The valve spring seat pressure is not enough so they cannot bring the valve back into the seat fast enough so the valves flutter, they do not seat properly which results in drastic cylinder pressure leak.

When a lifter is coming off a cam lobe(ramp) it is returning the valve to it's seated position. For example if the intake valve cannot come down fast enough to the seat because of low seat-pressure the combusted gas will then bleed back up through the intake and fire out the carb..


understand ?