Valve Float
 

I was reading about a post the other day about someone that redlined their tach and was afraid they might have "floated" the valves. What does this mean exactly? I'm unfamiliar with the term. Thanks!

The cam is turning so fast that the valve springs are not allowed to fully close the valves.

If the springs don't close the valves don't worry the pistons will!

Thanks, makes sense. . . what would be the best prevention for that (besides running the engine at a lower rpm) - stronger return springs?

Both stronger return springs, and solid lifters.
Not a good upgrade for the average racer.
The heads and manifolds don't flow well enough to warrant revving past 7000, which is where the valves will start floating.
You would see more power by upshifting than letting it rev up.

Typically valve float will not cause you to bend a valve. It can happen but that usually requires more than just redlining the engine. If you reach the RPM's necessary to blow the motor it probably wont matter wich parts exploded.

Alot of people will upgrade springs when rebuilding the head or installing a cam. The power band on your car is below 7000 RPS's though. So the best thing to do is to shift inside the power band.

The only problem with stronger springs is that the stock hydraulic lifter were not designed for them so then you can have another problem which would cause the lifter to collapse......

Now you see why porsche left the red-line where it is.

oops.

Thanks Roger, gee you learn something every day... I guess I can go back to bed now!

Shift in the power band? Now where is the fun in that!

Just keep it under 7 grand and you can have all the fun in the world.

hehe rx7 doesnt have valve float....

Re: Valve Float
 

Two scoops vanilla ice cream, add valves and root beer..
Sorry couldn't resist.