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Carb tuning ?


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CTLS runs good but right side starts running rough after few min. Put a inductive timing

light to check fire and it does not light up top side cyl. or the bottom same thing. Pull new plugs out

they are sooted black. install two used plugs its running perfect again timing light is firing like

it is supposed to. Then the other cyl. same side does same thing no fire top plug or bottom. Install

two more used plugs starts running perfect again timing light is working correctly on both. called Dean

and he said he has had this before on the right side of engine many times. Has anyone heard of this, mag

check is perfect when its running right this has happened a couple of times, carbs have been gone through.

I need to lean out the idle screw some I think that might help so its not to rich on idle. Will try that next.

 I find it hard to believe the plugs get sooted up and they stop firing, they are not wet just soot. Ideas

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The carbs by nature run super rich at idle to ease cold running. Depending on how low you set idle, there is a chance it could become rich enough to stall out on its own.

Thankfully, the old trick of adjusting the idle mixture screw is in the latest line maintenance manuals so there's your official data for it.

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It's probably coated in gas film that vaporized before you removed it.

Tom made a point to me years ago that I can't assume that the fuel gas mix is perfectly hemogenous. And it's true. It could be that at idle, the bottom plug gets bathed in rich fuel that can still combust, while the stuff at the top is too dry when the spark fires and doesn't contribute.

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