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Thread: Zz4
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10-13-2008 #1
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Zz4
OK, I have a used ZZ4 motor in the Camaro. First, i really like the engine- it's really sweet tempered. That said......Chevy claims the max safe rpm is 5800 rpm. I'm assuming that's due to valve springs. Can anyone set me straight if that's not the case.
If it is the case, can anyone make a reccomendation for a valve spring that will let me make some more rpm. That stupid little yellow light comes on too soon after I stomp it.
I know I could go to a cam manufacturer, but figgered i'd drop a hook in here, first
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10-13-2008 #2
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Your engine probably won't benefit from more RPM without a larger cam. GM is always going to error on the safe side anyway.
Todd
10-15-2008 #3
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The valve springs on the L98 heads used on the ZZ4 are marginal at best, especially with the ultra heavy hydraulic roller valvetrain. It'll take a bit more pressure to control the valve motion withthat set up. I'd venture to guess you'll start seeing valve float at around 6000 rpm. A quick fix (although not the best) is AFR's Hydra-rev kit. It applies additional spring pressure to the body of the lifter using machined cups that rest on the top of the lifter and locate a single spring held in place by a machined aluminum plate installed under the cylinder head where it overlaps into the lifter valley. Of course, if you're willing to disassemble the heads, some nice new beehive springs might be a good way to go.
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