valve float...whats it sound like?

[87NAT]

My car seems to "pulse" at about 24-25 psi of boost. I wouldnt say its an outright miss but its hard to describe. What does the car do when the valve springs are shot? My plugs are gapped at .32 so I dont know if its spark blow out. My car has Eastern Performance heads that were installed in 1994 but the car sat for 5 years in a garage before I bought it. Could just sitting kill the valve springs?

 

[SS/GNX]

Most of the time when you get valve float from bad or improper springs, it doesnt really make noise... at least not from my experience...

You just notice the power falls flat on its face in the upper RPMs...
Doesnt pull as hard as it should anymore...

 

[87NAT]

Sorry...I shouldnt say a noise. It just doesnt feel right up top. I have the useless stock LED tach so I really dont know what RPM's exactly I am at but with the stock cam its not over 5300. I guess I need to put an aftermarket tach and see whats up.

 

[mikestertwo]

Is the boost pulsing up and down or is it steady? Any knock?

 

[John Wilde]

This could be your springs.

 

[87NAT]

Boost is not steady...needle is moving 1-2 psi back and forth. No knock. Thats the pulse or miss I am seeing and feeling.

Pulls like a frieght train, rock steady and hard form 0 psi up until it it is to the floor and max boost. Then the problem starts . 3/4 throttle and 20 psi is rock steady....this just happens when at max boost.

 

[Turbo6Smackdown]

'nother question for ya. What would valve float change, on the scanmaster numbers, providing everything else was up to par. Would the condition it creates show up at all?

 

[VadersV6]

If the springs are bad, it usually wont make any noise. Power will just fall flat instantly at high rpm. Under alot of boost, the pressure can lift the intake valve off its seat...or actually keep it from ever completely sealing at all. You MAY see some boost pulsing from the cylinder pressure pushing its way back into the intake tract. My power falls dead on its face after about 4800rpm. Im pretty sure my exhaust isnt plugged, so ive always thought that my springs are probably dead...at least a few of them because my car sat for 4 years. The heads were re-done..I know that much. And it doesnt have stock springs. But when a valve is open and that spring stays compressed for 4 years, its going to lose most of its tensile strength. Springs by design, even automotive valve springs, do not last when they're repeatedly compressed beyond a certain percentage of their free relaxed length. Automotive valve springs are usually compressed beyond this percentage, even with stock motors with low lift cams. So its always necessary to replace them after awhile. For optimum life, they shouldnt be compressed beyond 25-35% of their relaxed length. The variation depends on tempering and the type of wire and a few other factors. When you run a higher lift cam and keep the stock style springs, especially when you just shim them to get the extra seat pressure, those springs are going to die way sooner than they normally would have.

 

[Turbo6Smackdown]

i see

 

[Junior Samples]

good reply vader

Mechanical resonance is the tendency of a mechanical system to absorb more energy when the frequency of its oscillations matches the system's natural frequency of vibration (its resonance frequency or resonant frequency) than it does at other frequencies.

hence galoping girdie

 

[adroit]

Aside from power loss can bad valve springs have any negative effects on the motor? Basically, are there any risks to running a car with bad valve springs, or is it just not as fast?