coil for 59ab with a crab distributor 6V pos.

[Planojc]

Been getting mixed answers on what coil to use on a 59ab 6V pos, with a crab distributor. The car, a 35 Ford, with a 6V 59AB has the original under dash ballast resistor for the old style coil, so I assume that using a modern can coil, I wont need it. The confusion comes on weather to use a 1.5 ohm or 3 ohm coil. I have read that the 3 ohm coils don't need a resistor and that the 1.5 coils do. I have a 6V coil that measures 1.5 ohms but it clearly states that it does not need an external resistor. I've also read that the 1.5 are for 6V and the 3.0 are for 12V. Anyone have a part number and brand that they can recommend?

[1942deluxe]

NAPA IC7, bypass the resistor.

[Flathead Fever]

There are all kinds of coils, some have built in resisters, some have external resisters, some are 6V and some are 12V, some are negative ground and some are positive ground. It's important you pick the correct one. There are also different condenser's too.

[tubman]

Originally Posted by Flathead Fever

There are all kinds of coils, some have built in resisters, some have external resisters, some are 6V and some are 12V, some are negative ground and some are positive ground. It's important you pick the correct one. There are also different condenser's too.

There are several misleading statements in the above. First of all, almost all coils are not polarity sensitive. The primary terminals are marked positive (+) and negative (-). They work fine if hooked up correctly. The only coils that are polarity sensitive are the ones with only one external terminal. The only one I can think of now is the coil for a Ford helmet distributor. I''m sure there may be others, but they're not common or germane here.

Second, I have found that the capacitance of a condenser makes little difference in general use. If you chose really bad on capacitance, it shows up as accelerated point wear. Most modern condensers are in the low .20's microfarad range and work fine in almost all cases. If you are experiencing unusual point wear, you can improve it by increasing or decreasing the capacitance of the condenser. Depending on which side of the points the buildup occurs determines which way to go. I saw it once in an old Motors's manual, but don't remember what it is. It is very uncommon.

As to what coil to use? You want about 4 amps going through the points; anything less than than will produce a weak spark, while more is hard on points. We have all heard of Ohm's Law : I=V/R (Current - amps=Volts/Resistance). For a 12 volt system, that means a coil with 3 ohms resistance 4=12/3, while a 6 volt system means a 1.5 ohm coil (4=6/1.5). These are just general rules that are superseded in real life with things like ballast resistors and the Ford under dash resistor, but can be used to make sure components are compatible. A multi-meter and a little basic math can go a long way.

[ford38v8]

For what Tubman says, I gotta believe it, and can only add this general note:
I have had extensive personal experience in testing automotive coils the old fashioned way, and know for a fact that the human body has three naturally occurring testing devices used while leaning over into an engine compartment. One is the back of the head, unless there is no hood on the car, the second is your elbow, useful in conjunction with any unforgiving hard surface that may be readily available, and the third, the most reliable of the three, being the fingers of the very hand you use to hold your important things. Should you get readings simultaneously from all three of your personal gauges, you can close up shop for the night in the happy knowledge that your coil is in great condition. 😵

[tubman]

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I have to agree, having experienced readings on all three sensors in the past (multiple times, I may add). That's why I now depend on a multimeter.

[Planojc]

Originally Posted by tubman

There are several misleading statements in the above. First of all, almost all coils are not polarity sensitive. The primary terminals are marked positive (+) and negative (-). They work fine if hooked up correctly. The only coils that are polarity sensitive are the ones with only one external terminal. The only one I can think of now is the coil for a Ford helmet distributor. I''m sure there may be others, but they're not common or germane here.

Second, I have found that the capacitance of a condenser makes little difference in general use. If you chose really bad on capacitance, it shows up as accelerated point wear. Most modern condensers are in the low .20's microfarad range and work fine in almost all cases. If you are experiencing unusual point wear, you can improve it by increasing or decreasing the capacitance of the condenser. Depending on which side of the points the buildup occurs determines which way to go. I saw it once in an old Motors's manual, but don't remember what it is. It is very uncommon.

As to what coil to use? You want about 4 amps going through the points; anything less than than will produce a weak spark, while more is hard on points. We have all heard of Ohm's Law : I=V/R (Current - amps=Volts/Resistance). For a 12 volt system, that means a coil with 3 ohms resistance 4=12/3, while a 6 volt system means a 1.5 ohm coil (4=6/1.5). These are just general rules that are superseded in real life with things like ballast resistors and the Ford under dash resistor, but can be used to make sure components are compatible. A multi-meter and a little basic math can go a long way.

This makes sense, 1.5 ohms for 6V and 3 ohms for 12V. Thanks for the info.