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Discussion Topic:
Under dash resistor
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jehn |
11-05-2016 @ 4:20 AM
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New Member
Posts: 101
Joined: Nov 2012
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Is there anyone who know the Ohm value of the under dash OEM resistor 18-12250 for ignition coil for 1932-48? Can that resistor be used when conversion to 12V if I have a 12V coil without resistor?
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40cpe |
11-05-2016 @ 6:51 AM
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Member
Posts: 475
Joined: Jan 2010
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I just put an ohm meter on mine yesterday, it measures 1 ohm. after the meter was on it for a while it settled in at .9 ohm. The resistance of the coil you have will determine how much needs to be added. Measure between the two small terminals to determine. Conventional advice says for 12V you need about 3.5-4 ohms.
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jehn |
11-05-2016 @ 11:54 AM
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New Member
Posts: 101
Joined: Nov 2012
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Thanks a lot for your advises 40cpe. I understand that the resist will change when current past true but 1 Ohm cold give me a good clue. If I use my existing under dash resistor I have to add a coil with 2,5-3 Ohms I suppose.
This message was edited by jehn on 11-5-16 @ 12:15 PM
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Drbrown |
11-05-2016 @ 9:21 PM
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Senior
Posts: 571
Joined: Nov 2013
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Most 12 volt coils made now have the internal resistor. Consistent with 40cpe's post, I have two such functional 12 volt coils and they read between 3.2 and 3.4 ohms.
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40cpe |
11-06-2016 @ 6:20 AM
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Member
Posts: 475
Joined: Jan 2010
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If you are going to buy a coil, the guys over on the Ford Barn recommend the Bosch Super Blue coil for 12V running points. It doesn't need any resistor.
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jehn |
11-06-2016 @ 8:02 AM
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New Member
Posts: 101
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Drbrown, do you even use the under dash resistor together with the coil? 40cpe, I know there is coils with internal resistor available but I have a few different in store.
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Drbrown |
11-06-2016 @ 9:14 PM
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Senior
Posts: 571
Joined: Nov 2013
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jehn .... To answer your question, no, I don't use the original coil resistor that's mounted on the Circuit Board under the dash. It was abandoned when the previous owner converted the car to 12 volts and installed a 12 volt coil. The Bosch Super Blue coil is often favorably mentioned in the forums. Not an inexpensive unit but you get what you pay for. I'm in process of buying one from Charlie NY. Side note: Coil resistant readings often drop as temperature of unit increases.
This message was edited by Drbrown on 11-6-16 @ 9:17 PM
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jehn |
11-07-2016 @ 5:01 AM
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New Member
Posts: 101
Joined: Nov 2012
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Thank you guys, I think I have the information i needed about coil resist.
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