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Rookie Coil Question
https://slantsix.org/forum/viewtopic.php?t=29217		 Page 1 of 1
Author:  hack4th [ Thu May 29, 2008 6:36 pm ]
Post subject:  Rookie Coil Question
The ignition coil on my 62 Valiant is old and I figure I'd replace it... does it matter which coil I get? I saw one called a MSD Blaster 2 that seemed ok (not that I really know...). It recommends using a ballast resistor. Is that 100% necessary or can I hook up the new one like the old one?

Thanks
Author:  emsvitil [ Thu May 29, 2008 6:47 pm ]
Post subject: 
You want a coil of about 1.5 ohms with a ballast resistor

or

3.0 ohms without a ballast resistor


I think the MSD coils run 0.7 ohms which is too low.
Author:  hack4th [ Thu May 29, 2008 10:58 pm ]
Post subject: 
sorry... too low for the Valiant or too low to use without a ballast resistor?[/quote]
Author:  emsvitil [ Thu May 29, 2008 11:22 pm ]
Post subject: 
0.7 is too low of resistance for the coil even with a ballast resistor with a stock ignition (points, or electronic)
Author:  dakight [ Fri May 30, 2008 4:52 am ]
Post subject:  Re: Rookie Coil Question
Quote:
The ignition coil on my 62 Valiant is old and I figure I'd replace it... does it matter which coil I get? I saw one called a MSD Blaster 2 that seemed ok (not that I really know...). It recommends using a ballast resistor. Is that 100% necessary or can I hook up the new one like the old one?

Thanks
The old one should have a ballast resistor too. If it doesn't then you may have other problems besides the coil.
Author:  SlantSixDan [ Fri May 30, 2008 5:17 am ]
Post subject: 
Wait, hold it a sec. Why are you replacing this coil? Is there a problem with the way the car runs? There's no call to replace it just because it's old. If it's faulty, or if you're upgrading the ignition system as for example by doing the HEI upgrade, then a new coil is called for. Otherwise, if you're keeping the stock breaker-points ignition, keep in mind that any kind of "high performance" coil can tend to shorten the life of your points and won't offer a benefit.

"Performance coil" is in quotes because no matter how high the voltage claims made for whatever coil you buy, it cannot "push" extra spark into the ignition system. It can only provide what the system "pulls". For that reason, a higher-output coil only offers a benefit in conjunction with a higher-output ignition system as a whole. The secondary voltage of the ignition system is determined by factors that do not include the voltage number printed on the coil's marketing literature, and will not change with coil replacement. That is: If the secondary voltage with your current system is 18kv, it will still be 18kv with any new coil you install.
Author:  KBB_of_TMC [ Fri May 30, 2008 10:17 am ]
Post subject: 
Many years ago a diagnostic place setup free ignition testing at our all-Mopar show - I stood there an hour and watched ~15 of ~20 cars be told "bad coil". I asked the diagnostic professionals, and they told me the coil is considered a wear item and does break down and wear out after 30 years.

From my personal experience, I've had a number of coils with ~10^9 sparks on them get weak (from internal arcing due to breakdown of the insulation?) and cause problems. They all tested OK with an ohm meter - the windings were fine - but the output was very low or nonexistent, sometimes intermittantly. I now just replace any coil that's so old.

I've also seen a brand new yellow plastic housing Accel coil that fried several stock Mopar ignition modules in a row within a few minutes of operation, but tested OK w/ an ohmmeter. I suppose it had a borderline secondary-to-primary breakdown internally.
Author:  SlantSixDan [ Fri May 30, 2008 11:11 am ]
Post subject: 
Quote:
Many years ago a diagnostic place setup free ignition testing at our all-Mopar show - I stood there an hour and watched ~15 of ~20 cars be told "bad coil". I asked the diagnostic professionals, and they told me the coil is considered a wear item and does break down and wear out after 30 years.
Wrong. Coils are not a "wear item", per se. They can certainly deteriorate, and they can certainly fail — just like any other part — but they are not a scheduled-maintenance item, nor do they deteriorate or fail on any kind of a predictable timeline.
Quote:
From my personal experience, I've had a number of coils with ~10^9 sparks on them get weak
We don't measure coil usage time in years, number of sparks, or miles. It's just not applicable the way it is with tires, filters, spark plugs, or any other real wear items. If a coil is faulty, replacing it is a good idea. If a coil is not faulty, replacing it is a pointless waste of money. The 75% fail rate being proclaimed by the "professional" diagnosticians you mention is about as believable as SCAAMCO's claim that "half" the transmissions they see don't need replacement. It just doesn't pass the reality check. Again: Is the car presently under discussion giving any real indication that there are ignition problems?
Quote:
I've also seen a brand new yellow plastic housing Accel coil that fried several stock Mopar ignition modules in a row within a few minutes of operation, but tested OK w/ an ohmmeter. I suppose it had a borderline secondary-to-primary breakdown internally.
It pays to remember that correlation does not imply causation. The coils you saw could've been improperly made, the Mopar modules have known quality problems, etc.
Author:  hack4th [ Fri May 30, 2008 7:45 pm ]
Post subject: 
Didn't mean to 'spark' a debate... :lol:

OK lame joke sorry.

Actually I was just gonna replace it because it was old, the car runs fine except for some vibration which could be fixed by a valve adjustment probably. After reading this I see there's no point in buying a new coil which is exactly what I needed to know. Thanks everyone for the info.
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