September 2, 200817 yr I know this sounds like a noob question. But I've always wondered how two pieces of metal rotate around thousands of times without completely destroying each other? How do they continually make contact without wearing faster than they do? Seems they would just destroy each other rather quickly. Okay end dumb question of the day.
September 2, 200817 yr I think its the soft metal, copper? There's a lot of flex and they're barely touching.
September 2, 200817 yr The contacts don't touch. The spark jumps the gap. The gap is very small, so it doesn't rob much voltage, or burn the contacts too much. Eventually, they do get burnt, and that is why you put on a new cap and rotor.
September 3, 200817 yr Author ah ha - they don't touch. i was wondering that. interesting then that the spark gets to jump that many times. at least at the cap and at the plug. so the distributor contacts only get warn down from the spark then? seems the distributor contacts wear quicker than the rotor? seems like it should be the other way around since the rotor is doing 4 or 6 times as much sparking as one disty contact?
September 3, 200817 yr Probably because it is easier on the metal for the arc to leave it than for it to arrive, if that makes sense. Look at how spark plugs wear, it is a similar effect there. Also, the rotor contact is wider than the target contact, and the point the spark leaps varies a bit with the ignition timing. And remember, the gap is really small, like a few thousandths of an inch, so it is no sweat for a coil to pump the spark over it, when it is designed to jump a spark 40 thou at very high pressure.
September 3, 200817 yr there are 2 lots of sparks in the ignition system, 3 if you count bad points. points, distributor cap, spark plugs.
September 3, 200817 yr Author great topic!hey don't make fun of me drew!! (hands to face..walking towards corner of room.....)
September 3, 200817 yr Author I think this beats my stock EA mpfi EJ thread, yeah?define "beats", that could be taken either way!
September 3, 200817 yr The spark on the points side doesn't really count. It is a different current there, that is the low voltage side of the coil. It is like a transformer. Well set-up points shouldn't spark very much, if at all, that is what the "condensor" (capacitor) is for, to cut down the arc at the points. Since that is a high current spark, it really eats the contacts. Points don't last long without the capacitor.
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