| murphy1936 | -- 12-07-2013 @ 10:02 PM |
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What can I do to get second point to fire Only one set fires. What causes this? N. What. Is the cause. 2. Book says A GROUND goes from pos. battery to cowl. Another from cowl to engine. I put both of them to chassis. Instead and one from cowl to engine. Should I change back to what book indicates?
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| ford38v8 | -- 12-07-2013 @ 10:34 PM |
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Murphy, first question: On an early ford, one set of points makes the connection, the other set breaks the connection. This setup is unique to ford, and is the best mechanical ignition system ever devised due primarily to this innovation. Question # two: Yes, I'd certainly change them back the way it came from the factory. Alan
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| murphy1936 | -- 12-08-2013 @ 2:13 PM |
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Thank you Allen, I perhaps should with the cap off rotate the rotor then second set on Mallory distributor might fire? Do you agree this is new to me John Super Deluxe 41
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| ford38v8 | -- 12-08-2013 @ 7:57 PM |
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Murphy, I didn't explain well enough. The two sets of points work together to make a single spark per cylinder. Using two sets of points allows a much longer dwell than does a single set. One set completes the circuit as it drops off a cam lobe, then the second set breaks that connection as it rises a lobe, effectively lengthening the dwell by the difference in time between the two point actions. Alan
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| 40cpe | -- 12-09-2013 @ 8:44 AM |
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What makes you think one set isn't firing? Dwell? or are you looking for a spark when they break?
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| murphy1936 | -- 12-09-2013 @ 12:49 PM |
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Yes looking for spark. And can see only one ??? Super Deluxe 41
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| deuce_roadster | -- 12-09-2013 @ 1:36 PM |
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Murph, you are making this more complicated then it is. As said above the 2 sets of points are working as one. One set "makes" the other set "breaks" You only see 1 of them spark (from the "break" set") You most likely won't see any spark from the "make" set. You are looking for a problem that doesn't exist. This is the way you learn about your ignition system and how it works. So take this knowledge and continue. It sounds like what you have is working properly.
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| Stroker | -- 12-09-2013 @ 4:43 PM |
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So...why did the early ford ignition have two points? The idea was to increase the dwell, or coil saturation time above what could be accomplished at that time in history with the physical constraints of an 8-lobed cam and one set of points. Eight cylinders required the ignition cam to have 8 lobes, and the geometry of that octagon-shaped cam meant that given its' shape, very little rotational movement of the cam existed to allow the points to remain closed. Only when the points are closed, does the coil receive voltage to build up it's electrical field, which must subsequently collapse when the points open to induce the secondary high-voltage within the confines of the coil to provide the spark. The result is that the time the points are closed (dwell), in most eight cylinder single point designs is very short; much shorter than 4 or 6 cylinder cams which respectively were square or hex shaped. Later ignition coils were quicker to respond, but the early Ford concept was quite clever for its' day. By using one set of points to "open" the circuit, and a second set to "close", the geometry of the octagon cam's closed or "dwell" period could be lengthened to saturate the coil longer than was physically possible with a single set of points. I apologize for this "elementary" and crude explanation, but I felt that there were some underlying concepts being glossed-over.
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