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While crusin @ 3000 suddenly gain 200 rpm. Stays awhile then drops back. If I pull back throttle will reduce but will later drop 200 rpm. Feels and sounds good elsewhere. Wondering if it might be a intermittent plug wire problem. Any suggestions?
 

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Discussion Starter #4
It has the same carb it's always had on it. It's a holley 750 with vacuum secondaries. At 3000 rpm I'm not close to the secondaries opening. This rpm changes sometimes happens @ other RPM's. I notice it most when just leisurely cruising. All off a sudden it will gain 200 rpm. If left alone it will usually drop back down within minutes. It will cycle like this over and over. If I pull back the throttle to original rpm it will later just drop back the 200 rpm. and I'll have to give it more throttle to regain the original rpm set.
 

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Replace your plugs, wires and cap and rotor. I had a plug problem in the past and I would lose 250 RPM per plug. It would start with one plug fouling out and then cleaning up, only to finally losing 2 plugs on a run. I went back to hotter plugs and problem solved.
 

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Really? I just had this same problem last weekend on my little LS. I had burnt through 2 plug wires and didn't even notice. I replaced the wires and it fixed the problem.
hummmmmmm sounds familiar: from years past


two other wires were shot, but not as bad as that one. Engine didn't want to rev much at all ....:)eh:)
 

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That's what you get for not running a LS Jon. You could have redlined that thing for another couple outings before replacing it, and still kept it as a spare.;)
them things are just a miracle engine ......... they could probably part the sea if you asked. :wink2:
 
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