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'49 8N Won't Fire

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Jim

07-28-2000 06:33:32




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Tried everything except new coil. Do these things ever go bad intermittently? I have 12V on the points-side of the coil with points open. Only 2V with points closed. Is this right?




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Claus is correct........Dell (WA)

07-28-2000 07:24:45




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 Re: '49 8N Won't Fire in reply to Jim, 07-28-2000 06:33:32  
Jim..... ..2 volts on a frontmount ignition coil is just too low, you need about 3.5 volts, 3 volt min and up to 4.5 volt max. Your 12 volt battery voltage with the points open is correct. Did you just suddenly start having this problem? If so, you've probably got some poor connections somewhere, check for clean and bright and tight. There is always the possiblity, that the "resistors" have gone bad. You should have 2 in a typical 12 volt conversion. The original "ballast" resistor and the 12 volt to 6 volt dropping resistor. Find 'em and measure what ya' gots and report back the readings if you can't make sense out of 'em. We're here to help..... ...Dell

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Jim

07-28-2000 08:06:51




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 Re: Re: '49 8N Won't Fire in reply to Claus is correct........Dell (WA), 07-28-2000 07:24:45  
What should the resistance be on the large resistor that is mounted close to the battery, on the firewall? I have 2 Ohms.



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Dell (WA)

07-28-2000 14:05:02




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 Re: Re: Re: '49 8N Won't Fire in reply to Jim, 07-28-2000 08:06:51  
Jim..... ....Measuring low value resistances is more of an approximation unless you are using lab grade ohmmeters. That said, even the cheepest multimeters will give you a reasonably accurate voltage reading, which is why I "quoted" you some numbers. Howsomever, in a typical frontmount 12 volt conversion, there are usually 2 resistors in series (like flashlight batterys). One of the resistors is the original 6 volt "ballast" resistor of 0.7 ohms mounted on the backside of the dash panel and then somewhere there should be a 12 volt to 6 volt droping resistor, which nomally is about 1.5 ohms and 50 watts (hotcha-hotcha). If you have a 2 ohm resistor that is too much resistance and will ultimately end up dropping too many volts and this is supported by your report of 2 volts at the ignition coil. Remember, the original 6 volt front mount ignition coil wants to see 3.5 volts (3 volts min and 4.5 volts max) anything else, you're going to have problems..... ..hope this helps explain..... ..Dell

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Claus

07-28-2000 06:46:29




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 Re: '49 8N Won't Fire in reply to Jim, 07-28-2000 06:33:32  
2 volts is too low. you should get about 3 - 3.5 volts at the coil primary with the points closed.
You may have some shorted turns in the coil or something else is causing high resistance in the primary circuit. One culprit is the ignition switch. Take a jumper and place it across the swithch. Also check your wiring for clean and tight connections.
Happy Motoring
Claus



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