10-11-2017, 09:32 PM | #1 |
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Coils
Can a 12v coil be run on a 6v system? I read many conflicting opinions.
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10-11-2017, 10:07 PM | #2 |
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Re: Coils
Hi there, If the 12 volt coil is marked on the bottom "use with resistor" or on its side label or on its box marked similar then it can be used on a 6 volt system with no resistor required. These coils are actually designed to operate on 6 to 8 volts. There are various types of 12 volt coils and you would need to test the primary winding with an ohm meter to determine what you have if it is not marked. Regards, Kevin.
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10-11-2017, 10:12 PM | #3 |
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Re: Coils
What value would you be looking for?
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10-11-2017, 10:49 PM | #4 |
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Re: Coils
Can a truly 12v coil be run on 6v using a 6v to 12v converter?
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10-11-2017, 11:36 PM | #5 |
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Re: Coils
flatjack, A 12 volt "use with resistor" coil will read approx. 1.2 to 1.8 ohms across its primary winding, depending on manufacturer. Remember this coil is designed to operate on 6 to 8 volts through an external resistor. Likewise a marked straight 6 volt coil will have similar ohms reading across its primary winding, ie approx. 1.5 ohms. A straight "marked" 12 volt coil will have a primary winding reading of approx. 3.5 ohms. Regards, Kevin.
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10-11-2017, 11:44 PM | #6 |
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Re: Coils
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10-12-2017, 12:21 AM | #7 |
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Re: Coils
How about the opposite; can a 6 volt coil be run on twelve volts?
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10-12-2017, 12:26 AM | #8 | |
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Re: Coils
Quote:
But the stepup will draw twice the current plus internal losses from the battery...and a stepup delivering in the 5A range cost more then a correct coil. |
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10-12-2017, 12:29 AM | #9 |
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Re: Coils
Just add a resistor to keep the current down to around 4A and it will work fine....The coil might work fine taking a higher current through it depending on if it has the cooling capacity or not...the points will burn out fast if you start pushing high current through them.
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10-12-2017, 02:04 AM | #10 | |
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Re: Coils
Quote:
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10-12-2017, 02:34 AM | #11 |
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Re: Coils
How about the opposite; can a 6 volt coil be run on twelve volts?
For years I ran my 35 on original 6 volt system, using a generic black bodied coil with a goldie colored top, no brand name. Subsequently, converted to 12 volts and still using exact same coil! No resistors anywhere in the circuit.My 8N tractor runs the same type coil, again, another conversion to 12 volt, again with no resistor! I've had many people tell me that this can't be done; that it'll burn up the 6 volt coil. I don't know why this hasn't yet happened after, what, about twenty five years.
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10-12-2017, 04:13 AM | #12 |
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Re: Coils
Brian, without knowing the specifications of your coils, ie primary winding resistance its hard to say what you have. A good test would be the current draw of each coil, engine stopped, points in distributer closed and ignition ON. Could also test current draw with engine running. A nice figure would be around 3 amps. Engine running test will show a lower current draw. More than 4 amps would be getting too high and points life would be reduced and would indicate that the coil was not suitable for 12 volt operation. Or it may need a resistor in line. Regards, Kevin.
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10-12-2017, 04:39 AM | #13 | |
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Re: Coils
Quote:
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10-12-2017, 08:34 AM | #14 |
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Re: Coils
The only problem we have these days is the fact that there are very few well made automotive condensers any more. If a person can get a good quality condenser, the OEM system works very well with good reliability. I would venture to say that it would likely be as reliable as the Pertronix systems since they are so sensitive to voltage spikes that that they tend to burn the module out at the drop of a hat. They have to have the right components for reliability and an inverter can also cause reliability problems if it's a poor quality unit. Way too complicated for me. I like simple and reliable.
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10-12-2017, 10:29 AM | #15 |
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Re: Coils
Quality condensers? I still have these available. Modern "severe duty" film capacitor in a classic "Trash Can" styled housing that mounts on the outside of the distributor housing. Lots of developmental time determining the proper components. I already have a bunch in the field, including my '51 Ford, '67 Corvette, and the Chrysler hemi in my dirt car. $40 plus shipping.
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10-12-2017, 11:09 AM | #16 | |
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Re: Coils
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system. This has been made more reliable by the introduction of the Ford coils from 32 to 48 being rewound and insulated with modern high temp materials by Skip Haney in Florida. He has rebuilt well over 20,000 Ford coils and removed the heat break down problems. In over 20 years NO ONE that has his coil ever paid for repairs to a coil he rebuilt. Using a stock coil and ignition makes finding a problem very easy to find and repair. Look at all the past posts on abortions to the ignition system, they go on and on trying to fix the problem. My advice, stay stock. G.M.
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10-12-2017, 06:07 PM | #17 |
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Re: Coils
I have been using one of Skips rebuilt coils and crab dist. maybe 12 years. Still going strong.
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10-13-2017, 08:25 AM | #18 |
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Re: Coils
i know if you run a 6 volt Ford coil on 12 volts it will blow its top off
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10-13-2017, 08:49 AM | #19 | |
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Re: Coils
Quote:
The problem is when the polarity is reversed the coil windings are not correctly wired. If the 6 volt coil is run on 12 with the 6 volt resistor the coil will get hot and melt the tar in the coil and leak. Let get hot enough it will split the top of the coil. On a normal 6 volt system if the ignition switch is left on and the engine is not running there is a 50/50 chance to melt the coil. The 50% come in as to whether the points are open or closed. If closed the windings become a big resistor and depending how strong the battery is will melt the coil or with a weak battery it will run down. Points open there is no connection of the windings to ground. The real danger is with the ignition switch on and a battery charger running. This could lead to the coil catching on fire. The only way a Ford 6 volt coil with the original Ford resistor will melt is with the ignition switch left on and the engine not running. G.M.
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10-13-2017, 09:00 AM | #20 |
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Re: Coils
Guys this is a difficult discussion to follow and many of the replies are correct . However we need to stop and qualify a couple things.
What coil are we discussing ???? The early ford six volt coil or a later can type coil? The early Ford Helment coil drives down the road at approx 3.4 volts after the resistor , this was changed when the coil went remote on the 1946 to 48 and then again in 1949 to 1953. Each system is a stand alone issue and each primary coil circuit is a different discussion. Then add the fact that we use aftermarket coils from many suppliers with no regard to the actual factory design and the problem gets worse. I just was trying to help a friend with a ignition issue and finally after a year or so of problems he brought the coil and distributor into the shop for me to look at. The coil was green and said John Deere on it!! Testing showed very low resistance, i asked where he got that coil and he said off my neighbors lawn tractor!!!! Maybe we need to start another thread and qualify the type of coil being discussed and forget the convertor issue ?? |
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