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Old 01-19-2019, 12:47 PM
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Phx Mike Phx Mike is offline
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Location: Phoenix, AZ
Cobra Make, Engine: Kirkham 427 s/c with Pond block 482 FE built by Craft Performance Engines
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I have dealt with this a lot over the years - factors contributing to dieseling or run-on include

- increased compression ratio
- increased idle speed
- low fuel octane
- excessive ignition advance at idle
- carb rich
- hot spots (in particular fouled plugs)

Try lowering your idle to around 750-800 rpm, and advance to around 12 degrees max at idle, and make sure you are running unleaded premium fuel.
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