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Old 05-22-2013, 09:01 PM
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If you're using manifold vacuum for the vacuum advance, swap it over to ported. There are cases where the sudden loss of advance at the hit of the throttle (caused by a manifold vacuum-equipped vacuum advance) will cause a *pop* through the carb, similar to a lean condition.

If this is the problem, it can be dealt with so you can still use manifold vacuum if you wanted. But trying it will at least rule out or verify it as the core issue.
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