The Ford Barn

Wars37 · 02-28-2025, 09:42 PM

I have a 37 flathead model 60 with external 6v coil and I want to replace it . Can i use any coil as long as the + wire goes to the distributor? I have a ballast running before coil. Also I want to change my condenser ,can I use any ford condenser ? Thanks for any help.

JayChicago · 02-28-2025, 10:55 PM

Coils are rated by their electrical resistance, not voltage. With your resistor in the circuit, you need a coil about 0.8 to 1.0 ohm. Or you could use a 1.5 ohm coil and then by-pass the resistor. Don't get a 3 ohm coil, it needs 12 volts to push current thru that much resistance.

Just about any automotive condenser will work. They vary somewhat in their microfarad ratings, but the ignition system is not fussy about the condenser, almost any of them will work ok.

Wars37 · 03-01-2025, 08:24 PM

How do you check ohms ?

koates · 03-02-2025, 01:35 AM

Use a digital multimeter, set to ohms x 1 and connect to the pos and neg terminals of the coil primary. Why do you need a new coil. Do you have some kind of a problem ? Buy a Mallory 400 condenser on ebay. They are better than most other condensers for your Ford. Regards, Kevin.

Wars37 · 03-02-2025, 07:00 AM

Just bought the car I have a no start but noticed the coil was hooked up backwards neg was hooked up to positive supply . I cleaned the points but still no spark.

tubman · 03-02-2025, 10:17 AM

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Get yourself a multimeter if you don't already have one. You can get a decent one for about twenty bucks. You can use it to check your coil quite easily. There should be at least 10,000 ohms resistance on the secondary windings (coil tower to one of the side terminals), and less than 10 ohms on the primary windings. Any significant differences or a zero reading means a problem.

After that, you can use it to figure out your ballast if any and coil. Normally, a set of points will tolerate up to 4 amps before premature "burning" sets in. That's why 6 volt and 12 volt systems run coils with different resistance factors. Ohm's Law comes into play here.

I (amps)=V (volts)/R (ohms)

To get 4 amps across the points in a 6 volt system, you need 1.5 ohms resistance through the coil. For a 12 volt system, you need 3 ohms. With 12 volt systems, the manufacturers sometimes used a 3 ohm coil. However, old habits are hard to break (and 6 volt coils were available and cheap), so they used a 6 volt coil with a 1.5 ohm ballast resistor and called it good. Then, they got the idea to bypass the ballast resistor during starting so the system got 8 amps for a short while, which aided starting and really didn't harm the components.

02-28-2025, 09:42 PM	#1
Wars37 Junior Member Join Date: Feb 2025 Location: Brooksville Florida Posts: 6	coil 6volt I have a 37 flathead model 60 with external 6v coil and I want to replace it . Can i use any coil as long as the + wire goes to the distributor? I have a ballast running before coil. Also I want to change my condenser ,can I use any ford condenser ? Thanks for any help.

02-28-2025, 10:55 PM	#2
JayChicago Senior Member Join Date: Jan 2019 Location: Chicago Posts: 927	Re: coil 6volt Coils are rated by their electrical resistance, not voltage. With your resistor in the circuit, you need a coil about 0.8 to 1.0 ohm. Or you could use a 1.5 ohm coil and then by-pass the resistor. Don't get a 3 ohm coil, it needs 12 volts to push current thru that much resistance. Just about any automotive condenser will work. They vary somewhat in their microfarad ratings, but the ignition system is not fussy about the condenser, almost any of them will work ok.

03-01-2025, 08:24 PM	#3
Wars37 Junior Member Join Date: Feb 2025 Location: Brooksville Florida Posts: 6	Re: coil 6volt How do you check ohms ?

03-02-2025, 01:35 AM	#4
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,185	Re: coil 6volt Use a digital multimeter, set to ohms x 1 and connect to the pos and neg terminals of the coil primary. Why do you need a new coil. Do you have some kind of a problem ? Buy a Mallory 400 condenser on ebay. They are better than most other condensers for your Ford. Regards, Kevin.

03-02-2025, 07:00 AM	#5
Wars37 Junior Member Join Date: Feb 2025 Location: Brooksville Florida Posts: 6	Re: coil 6volt Just bought the car I have a no start but noticed the coil was hooked up backwards neg was hooked up to positive supply . I cleaned the points but still no spark.

03-02-2025, 10:17 AM	#6
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 11,639	Re: coil 6volt Sponsored Links (Register now to hide all advertisements) Get yourself a multimeter if you don't already have one. You can get a decent one for about twenty bucks. You can use it to check your coil quite easily. There should be at least 10,000 ohms resistance on the secondary windings (coil tower to one of the side terminals), and less than 10 ohms on the primary windings. Any significant differences or a zero reading means a problem. After that, you can use it to figure out your ballast if any and coil. Normally, a set of points will tolerate up to 4 amps before premature "burning" sets in. That's why 6 volt and 12 volt systems run coils with different resistance factors. Ohm's Law comes into play here. I (amps)=V (volts)/R (ohms) To get 4 amps across the points in a 6 volt system, you need 1.5 ohms resistance through the coil. For a 12 volt system, you need 3 ohms. With 12 volt systems, the manufacturers sometimes used a 3 ohm coil. However, old habits are hard to break (and 6 volt coils were available and cheap), so they used a 6 volt coil with a 1.5 ohm ballast resistor and called it good. Then, they got the idea to bypass the ballast resistor during starting so the system got 8 amps for a short while, which aided starting and really didn't harm the components.