I have heard this expression used, when talking about cams. My questions are: 1) What exactly is Valve Float?? 2) What would I noticed if I had Valves floating??

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Godti
'89 Trans Am (Red)
305 TBI 5spd

 

Happens when the valve doesn't close before it's pushed open again(never closes). Too many rpm's for the valvetrain will cause it, and power will drop off big time.


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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

In extreme cases when the valve begins to float constant the piston will slam into it and bam! The engine will probably lock up when the valve gets jambed in the head or one cylinder will die when the lifter gets crushed and it doesn't do much good for pushrods either.

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1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 Trans Am T-tops
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

 

Thanks, the reason Im asking is cause, at WOT I have a jerking sensation in the car. Its like one piston is not firing or something. Its not a big jerk, you can just feel it through the car, you probably could see it if I was ripping by you. Basically I think I could climb to 60mph faster if I didn't have this lag on the car. I dont know if this is making any sense, but Im just trying to get some info. If one of my rings was toast, what would this do?? If my seals on my valves were going or gone, what would this do to my car???

Something else, if the engine was not gettting enough gas at WOT, what problems would I notice?? COUld this be it, maybe??

I have not done any mods, except for exhaust, and I had this problem before that.

Thanks


[This message has been edited by Godti (edited January 29, 2001).]

 

Sounds like a minor miss to me.

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1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 Trans Am T-tops
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

 

I vote for an ignition miss.

Valve float can be put in two categories.

1. The lifter looses contact with the camshaft, especially after the peak lift of the camshaft.

2. The valve and spring are driven at their first harmonic resonance frequency (that's a mouth full). Imaging a paddle ball - at a certain speed (frequency) the ball oscillates with the smacking of the paddle. Similar concept with the valves and springs. The cam lobe smacks the valve (or lifter) and compresses the spring. When done at resonance frequency, the valve will reopen (oscillate) like the paddle ball. This is much more detrimental for the exhaust valve than the intake. That is because when the exhaust valve is closing, the piston is at TDC.

If the exhaust valve does not hit the piston, then during the intake stroke, both valves are open. The exhaust valve lets burned gases back into the cylinder. This is why valve float can act like a governor.

 

Could you give me some more info on the ignition miss?? I replaced the cap and rotor, and the ingition coil. What else should I be looking at here??

 

Plugs and wires would be the next culprits. After that try then ign. module if those don't solve it.

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1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 Trans Am T-tops
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

 

check your fuel pressure too.