Thread: Spark plug burn pattern?

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If it were my carburetor, I'd probably want to start with the Owner's Manual...
http://www.edelbrock.com/automotive_...ers_manual.pdf

Travis,
A little more information might help here. Is this a new problem, that is, was this engine running fine, but just started this "backfire under load" problem or is this a new configuration of parts you're trying to sort out? What is your ignition system/distributor that you expect is bad? Is the burn pattern shown consistent on all cylinders? And just for grins, what engine are we talking about here, and is it generally stock or heavily modified? Welcome to CHR, by the way

As rspears says need more info. Backfire under load would first look at cap and rotor for crossfire arcing. Try separating plug wires to see if makes a difference.