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Old 11-03-2003, 09:29 PM
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Valve Floating

Hello,
I've reved my car up to six grand before in park( i know its bad) and it went up fine, but when I am in gear and get to about 5,000 it starts to jerk and won't go up anymore. Why is this. Why does it go to 6,000 in park, but when it is in gear It can bearly do 5,000. I really would like to know why it does this?

Thank you a lot

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Old 11-03-2003, 09:32 PM
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There is no load on the engine in Park.
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Old 11-03-2003, 11:02 PM
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its not really that great for your motor to rap it up under no load either.
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Old 11-04-2003, 08:39 AM
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Id say right off hand your valve springs are shot...Most of the time when you experiance valve float below, 5500 with a hdy cam, its the valve springs, Id replace the springs and try to match the springs to the cam for maximum rpm and top end performance...
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Old 11-04-2003, 09:18 AM
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Valve float is the result of the lifters not being able to follow the cam profile, usually because of worn or inadequate valve springs. When a hydraulic lifter is tossed off the nose of the cam, the plunger is extended and the reservoir fills with oil. This is referred to lifter pump-up and it results in the valves not being able to close all the way, and the engine will miss for several revolutions, until the lifters resume their normal operation.
If the engine just plain runs out of grunt at a lower RPM, then it may be the result of many things. Small carburetor, low float levels, inadequate fuel pump volume, bad ignition, restricted exhaust, etc., etc. This could turn out to be a long list.
If your engine is a stock 2 barrel with single exhaust, 5000 rpm might be the maximum it is capable of.
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Old 11-04-2003, 09:55 AM
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I don't think this is a case of valve timing. I'm guessing the igniton is to blame. Under load the ignition system can't generate the needed pressure from igniton modules inability to full charge the coil at those speeds.
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