Valve float at 6000RPM?!?!

[grebnut]

hey... i was out driving in the snow and nastyness that the puget sound is tonight and i started slipping in second on snow and just kept it pinned and it went up to about 5900 and sorta acted like it had a rev limiter. i am under the impression that there is no limiter on my car! correct? i think so.... anyways,

i was thinking that it might be valve float because it sounds very much like a backfire. maybe intake air and fuel get past the valve and ignite in the turbo or downpipe and backfire? im running only a downpipe, no exhaust.... and 11lbs of boost on an other wise stock engine (open element filter too)

is this a really bad thing if it is valve float? im under the impression that the engine can be damaged by valve float... is this true? where can i get better parts that will hold more boost and im looking at getting a camshaft as well, and that wont help the situation!! what has everybody else done to combat this?

also, i think the valvetrain is probably 160000 miles old with the rest of the engine, so is it just old and worn out?....

thanks for all your help!!
ben

[GTJordan]

you have a 6K rev limiter

Jordan

[linuxman51]

:::chuckles::: heheheh, don't feel bad, it happens to the best of us :lol: :wave:

[grebnut]

lmao.... are you serious?!!?!?!? wow...... and i thought i knew quite a bit about my car! lol..... allright! well, that solves that problem.... ;) lol... thanks then! :)

ben

[davidmacq]

So that mean you don't have to worry about valve float at all? Even if you have a manual? Can rev it to redline with clutch engaged and not get valve float?

Any LH equipped car can be run face-first into the rev limiter w/out worries. I've done it a million times. If I feel the cut as the clutch is going in for an upshift, I know I'm squeezing every last rev out of the powerband. Stock valvesprings in the redblocks should be good up to at least 7K RPM w/out float - the K-Jet (2.1L) cars had a 6500RPM redline, but no limiter. And those with MS are gleefully raising their limits by at least 500 or so RPM.

[boostdemon]

i start to get valve float around 7500rpm... some stiffer springs would help. Valve float is a better "soft redline" i think, no fuel cutting etc..

I don't think it is a good idea to bang off the rpm limiter as a matter of course. The rpm limiter is a fuel cut on the LH 2.2 and 2.4, and its effect can be quite harsh on the drivetrain. I am pretty sure that I have ruined a few AMMs due to this. Consider the effect of cutting and restoring fuel repeatedly at maximum rpm and maximum load. It can't be good and the damage could eventually be more than an AMM. At light load, like playing around in the snow or rain, the chance for harm is much less and the effect that you feel is similarly diminished.

Philip Bradley

[Anonymous]

My valves feel like they're floating by 6,000, but I'm using the large diameter springs and retainers in my 405 head... I certainly can't rev mine too far above that - it sounds awful. I've got a valve/spring/retainer assembly in my bag and will be stopping at a VW shop one night this week to see about Bugpak springs. Someone mentioned them once upon a time and I'm just now getting around to following up on them. Anyone got a part number or application???

[Cliff]

How does it feel or sound when the valves starting to float.

[dl242gt]

My 82 seems to start to float around 6500 rpm. Of course you can't be sure about the accuracy of your factory tach either. I usually rev mine
to an indicated 6k or just over. Much more and I start to hear some float.
Of course with 293k miles and now with a high lift cam. Valve float at 6.5k is perfectly acceptable to me.

It's just more evidence of how tough these motors really are. Because mine sees that 6k just about every time I drive it.

[Hank Scorpio]

I had mine rev limited to 7k, and had no float (as far as I could tell) pulling to 6800 every shift. I do have upgraded springs now... just haven't had a chance to drop them in yet.

[940 T.U.R.B.O]

somebody help me out cause maybe i had it wrong all this time. I thought valve float was the enemy to be avoided at all cost because it could possible put the valve into the face of the piston? which would disasterous at the top of the powerband (i.e. redline) Plus i thought rev limit had more to do with the ECU controlling ignition and pulling ignition out so that it wouldn't spark, and not valvetrain assemby. I mean i've tapped the rev limiter before not paying attention on a wet road, but it scared the shyte out of me.(maybe i'm just to cautious) Is hitting the rev limit not a worry because of our motors not running an interferance design? I'm not saying I'm right at all, just saying if I have it backwards then let me know now before any further miseducation.

mike (as usual)

[linuxman51]

its possible to hit the piston altho in most instances with our cars not extremely likely... but definitly a possibility. It appears naerdowell tensioners are more to fear than valve float..

[MikeHardy]

yeah the only time my valve hits the piston is when i was putting the V cam in and my piston was TDC and i had a valve all the way open. it didn't hit till just before peak lift

[JohnLane]

i start to get valve float around 7500rpm... some stiffer springs would help. Valve float is a better "soft redline" i think, no fuel cutting etc..

Uh Yikes!! Guess again folks.
Valve float is not a gentle thing when it happens. Junk tends to break when it does happen. Any of us who have seen slowed down footage of what happens in valve float will see to it that it never happens in any of our motors. Valve float is when the valve springs are no longer able to manage the valve as it goes back and forth. The frequency at which the spring buzzes is a part of this program. This is why double springs have two sizes of wire. The speeds at which it all gets ugly will be different for the different sizes of wire, and they will help to dampnen each other, as well as increased spring rate all for higher speeds and being able to have things not beat themselves to death and break with larger heavier then stock valves.
Valve float=Bad.
Lots of other things go to hell at higher speeds/loads that can be mistaken for valve float.
Every time that I have experienced valve float I have got to disassemble broken junk for the post-mortem.
Thoughts?
JohnLane.

[Two245Turbos]

I agree with the last post..Why push it up to that point and keep it there :e-shrug: VRoooommm...CLUNK!CLUNK!.....Oh Crap!

[boostdemon]

[quote:e0dd623055="tryckjävel"]i start to get valve float around 7500rpm... some stiffer springs would help. Valve float is a better "soft redline" i think, no fuel cutting etc..

Uh Yikes!! Guess again folks.
Valve float is not a gentle thing when it happens. Junk tends to break when it does happen. Any of us who have seen slowed down footage of what happens in valve float will see to it that it never happens in any of our motors. Valve float is when the valve springs are no longer able to manage the valve as it goes back and forth. The frequency at which the spring buzzes is a part of this program. This is why double springs have two sizes of wire. The speeds at which it all gets ugly will be different for the different sizes of wire, and they will help to dampnen each other, as well as increased spring rate all for higher speeds and being able to have things not beat themselves to death and break with larger heavier then stock valves.
Valve float=Bad.
Lots of other things go to hell at higher speeds/loads that can be mistaken for valve float.
Every time that I have experienced valve float I have got to disassemble broken junk for the post-mortem.
Thoughts?
JohnLane.[/quote:e0dd623055]


hmmm. i've probably hit it about 10 times in 2 different k-jet cars, nothings broken (yet), i've hit an overboost fuel cut and broke the syncros off my 3rd gear because the jolt kicked the tranny out of gear.

maybe the nice lack of power and loud rattle/grinding/etc noise up in the 7500 rpm range is something else.. but it sure fits the description of what i know valve float as :???:

[mikep]

How does it feel or sound when the valves starting to float.
Power goes soft, and it goes "mooo". Seriously. Although it sounds different in various engines, and I have not floated them in a Volvo. I used to float them in my 2TC, and in a couple other pushrod engines.

[towerymt]

I hit the rev limiter hard in 1st once when my dad was driving behind me, and he said it puffed a cloud of white smoke. I figured if there would be smoke, it would be black, thinking ignition was cut rather than fuel. Apparently not.

[stylngle2003]

i hit the rev limiter quite frequently, like when i'm drifting around town or in the snow/rain. i did this once at the dragstrip too on the 2-3 shift...never see nany smoke tho.

Billy

[Boris740]

Any LH equipped car can be run face-first into the rev limiter w/out worries. I've done it a million times. If I feel the cut as the clutch is going in for an upshift, I know I'm squeezing every last rev out of the powerband. Stock valvesprings in the redblocks should be good up to at least 7K RPM w/out float - the K-Jet (2.1L) cars had a 6500RPM redline, but no limiter. And those with MS are gleefully raising their limits by at least 500 or so RPM.

How can Megasquirt overcome the rev limiter? It des not control the ignition but fuel injection only.

[stylngle2003]

cuz the oem rev limiter is a fule cut...plus megasquirt does have a spark function now as well, called megasquirt-N-spark :wink:


Billy

[jjam184]

Quote-- How does it feel or sound when the valves starting to float.


mmmmmmmMMMMMMMMNNNNNNNNNNAAAAANAANANANANANANAANNAA ANAAA.

Sorry, couldn't resist.

[dadstoys2]

How can you increase or overide the stock 6k rev limiter?
I have never heard of anyone able to do this other than with MS or MS& MS(spark)
I only would like a little bit past the 6k not to blow it up or anything. Just that the 6k kill sucks when your running it hard and it falls on it face on ya.
~Rich