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lean pop...I think

Old Jul 18, 2008 | 04:12 PM
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Default lean pop...I think

Help,

I have a stock 72 270 hp and it runs ok at speed but "pops" through only the right side exhaust at idle and when slowing down.

Carb ? valve ?

Thanks
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Old Jul 18, 2008 | 04:26 PM
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Could be a burnt valve.
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Old Jul 18, 2008 | 04:33 PM
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Originally Posted by fuelie65
Help,

I have a stock 72 270 hp and it runs ok at speed but "pops" through only the right side exhaust at idle and when slowing down.

Carb ? valve ?

Thanks

That popping usually means a lean condition. Since it's one side only I would suspect an air leak somewhere...maybe the intake is sucking air from around the gasket and richening one or more cylinders.
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Old Jul 19, 2008 | 09:48 AM
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In addition to the info others have provided, I would check the operation of your heat riser. If it gets stuck up or frozen it can impede the exhaust flow.
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Old Jul 19, 2008 | 01:25 PM
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Fuelie65,
Let us know what you find out, I have the same problem from the left side of my exhaust when letting off of the gas. I run Hooker Herder side exhaust with STS baffles .
Thanks
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Old Jul 19, 2008 | 07:47 PM
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Default Possibly a valve

Since popping is usually caused by unburnt fuel igniting in the exhaust system, I would look for either a valve, ignition wire, or spark plug problem. If a plug is fouled or ignition wire shorted on that side of the engine, then it may not be burning as efficiently as it should. Likewise, a valve not seating properly on that side could also cause the same problem.

I would think that a carbeuration problem would be independent of which side the popping occurred and would likely pop from both sides. Hope this info helps and good luck!
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Old Jul 19, 2008 | 09:46 PM
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If you suspect a valve might not be seating properly, take off your air cleaner and with the engine running spray a spritz of water into the top of the carb. The water will vaporize into steam, and break away carbon buildups that might be keeping a valve from seating properly. The water won't hurt anything if it's done in moderation. I did this once and was amazed at all the black crap that came spitting out the exhaust. A white cloth confirmed the discharge.
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