I think it is when you are running too many rpm for valve springs and they dont have strength/time to stretch back out and the valve ends up staying open?

Correct. The valves are traveling too fast for the springs so the valve actually "Floats" and usually hits the piston then things get ugly fast!!!!!

Whay do you ask? Looking for another way to explain to your dad why you need a new engine? Such as, the old engine has a higher potential for valve float, so you should upgrade it now!!

Yes, the valves stay open longer than you want because the valve springs are not keeping the lifters in contact with the cam lobes.

Everyone here is correct in stating that valve float starts with the spring not being able to return the valve to the closed position. The other issue that comes into play here is when the valve/spring are not in the closed position the plunger in a hydraulic lifter will try to take up the "clearance" that this creates in the valve train, assuming you've preloaded the lifters and you're not running the lifters at zero lash.

So, If I just floor it in neutral with no revlimiter, how much damage do you think I can do? Wouldnt do that, then dad wouldnt let me take it out and run 45.0 on GPS

Hyperbaja


I agree with Crazyhorse in that it involves the valve staying open too long as all the other opinions...but this may also be a consideraton; if you board the throttle and let the float last until the oil gets too thin to lube the top end and the valve hangs up, its going to meet that pistonat an UGLY rate...smash bang BOOM. If your trying to save the motor for any kind of rebuild, keep in mind that the rods usually get bent and somtimes you can snap a crank shaft as well as send pieces through the engine block. If your trying to get a new motor, just advance the timing a bunch with crappy gas for yum yum and THEN board the throttles...and stand back. Detonaton, especially really bad as this will be will blow up that mooring block ALOT quicker than valve float and it will do the job right...holes in pistons, cracked cylinder heads, blocks, etc. Not that I condone such cruel treatment to the good old pushrod v-type gas engine, but hey, if "dad" needs convincing, this will CERTAINLY do it.

You guys are all wrong!! valves don't float,everytime I throw one in the canal they sink!!! just kidding,you know ,stuck in the house on this weekend,three days off and can't even use the boat sitting behind my house tripps


P.S. those guys are tellin the truth

lack of oil and high rpm (not necessarily extended) kinda sorta tend to do bad things in a motor too... and not just totally grenade it. not that i condone such activity

Lack of bearings and water are also bad really bad at rpm ,and I like jaroot don't condone this

Ok, so if I advance the timing, run marina gas and floor it on the trailer....

Wont do this, just heard the term a lot, never knew for sure what it meant.