09-11-2013, 06:32 AM | #1 |
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coil question
I was reading through my V8 Times and got to the Tech section where I read about the markings on a tube style coil. The person asking the question had a 51 Crestliner and was going to replace the coil. His old coil had Bat and Dist for terminal markings. The replacement has + and - as does mine. He asked if the + marking was the same as Bat on the old.
Cecil's response was "Assuming you still have the factory positive ground system on your car, the "+" terminal should be connected to the distributor and the "-" terminal should be connected to the ignition switch. In other words: Bat = Negative and Dist = Positive." I connected my new coil "+" terminal to the ignition switch. The car starts and runs fine. Could this be why my original coil failed? Should I switch the wires, or?
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09-11-2013, 06:50 AM | #2 |
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Re: coil question
With a Positive battery ground the + mark on the coil should go to distributor and through the points to ground. The - mark on the coil should go to the ignition switch through the resistor. G.M.
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09-11-2013, 06:53 AM | #3 |
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Re: coil question
G.M. is correct. You need to hook up your coil correctly.
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09-11-2013, 06:56 AM | #4 |
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Re: coil question
Thanks, have I done any damage? It's been 300 miles since I installed the new coil.
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Gene |
09-11-2013, 07:26 AM | #5 | |
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Re: coil question
Quote:
Two things happen when the coil is hooked up backwards. 1-Being as the coil is a "tapped transformer" it looses as much as 80% of its reserve power. This makes the car need a tune up quicker as theres no ( or very little reserve output ) . A couple times over the years a oem vehicle left the factory wired backwards. May run ok but over time wont provide the spark needed. 2-The residual magnetism of the center iron core is also reversed per design and cant be reversed. Once a coil is running backwards for a period of time it cant be simply reversed..... I just tested the output of a positive ground coil yesterday, tested good using a positive ground, reversed the leads and the coil had very little output..... |
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09-11-2013, 07:35 AM | #6 | |
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Re: coil question
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Quote:
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09-11-2013, 07:42 AM | #7 | |
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Re: coil question
Quote:
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09-11-2013, 08:14 AM | #8 |
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Re: coil question
Based on what I'm reading, since you have a Neg. ground car, you are also backward.
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Gene |
09-11-2013, 08:17 AM | #9 |
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Re: coil question
Well heck, I hooked it up like the old one came off, I didn't know if it would run either way or not. I found this on internet, I better switch mine around!
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09-11-2013, 09:31 AM | #10 |
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Re: coil question
After FoMoCo and the other major manufacturers went to 12-volt negative ground, the coils started being marked with polarity instead of component ID. This lead to a lot of problems with service parts back in that time frame. There is a pencil lead test at the high tension lead to check polarity but you can also purchase a polarity tester that has a little window to see the spark reaction. The tester plugs in line with the high tension lead. They are still available form several early Ford parts suppliers.
I have heard of coils that were not correctly marked for polarity but I guess it depends on the manufacturer whether they check them or not. In this day and age it pays to check everything with a healthy dose of skepticism. |
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