In Reply to: Re: Front dizzy posted by Beth and Allen on April 01, 2013 at 10:37:05:
1962 HI-PO engine option used dual points, too, as did 1942 flathead Ford V* and probably many others. The "how they work" part is that the two sets of points are arranged (relative to cam lobes) such the one set opens & closes later/earlier than the other. This allows set#1 to close, then a few degrees later set#2 closes, then when set#1 opens, set#2 remains closed for a few more degrees, thus yielding a longer dwell period than either set could produce alone. Longer dwell is important in a high RPM engine so that coil has time to reach maximum current on its exponential ramp-up.
2200 RPM doesn't qualify for "high RPM" and not 3500 either. Only beneficial when RPM is so high that the available dwell time is insufficient for coil to reach full current necessary for a good hot spark. Even on 1960's era V8s, this was north of 5000 rpm & a V8 cam design will always produce less dwell time than a 4 cylinder cam design.
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