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Strange Briggs

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Big Ten was running good then the past few days started popping/ backfiring. Checked points today, still set at .020, closed 'em down to about .016 and now runs beautiful. Only Cast Iron Briggs on the place runs good set at anything but .020. Is this a warnning of some kind?

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Marty, You may call it an "Omen", but I think it is just circumstances. Honestly, on my B/S engines that have the screw to adjust the points, I use the .020 setting just to get them started. Then I warm up the engine, and throw it wide open (3600 rpm) and adjust the points while running, just like adjusting the carb. So, honestly, I can't tell you where my points are actually set. I like equipment that can be "tweaked" during operation. Sure makes things a lot easier. Am I the only one who adjusts the B/S points with the engine running at WOT?

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I wouldn't be too concerned. Point gap will change the timing. The closer the points are set, the sooner the points open, thus the earlier the spark. Maybe the magneto on this engine timed at slightly more advance than your other engines and opening the points retards the spark slightly to compensate. Condition of the points may also be the cause. If the points aren't smooth, you don't get an actual reading with a flat gauge and you may have a .020 gap with a .016 setting. As you can see, a flat feeler gauge will sit on the high areas which won't correspond with the true gap that comes from the actual mating of the high and low areas.

If you used a .020 gauge to set the points as pictured, you'd have possibly a .024 true gap.

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Nice diagram Pat thanks. Never tried setting them with the engine running Rod, may have to give that a shot. Thats the way I used to set the timing on my 273 Dodge Dart for dragging, after I tightened the tapets a bit for full power shifting.

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coils a gettin weak,or bad wiring,possib,, wont build enough volts to work at 020 anymore? Ha!,,.I have a few motors around here only run with points just barely open,,can you say,, magnetron! gotta repolarize flywh,I know,,

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