Ignition coil

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Ignition coil

Postby Emerica1975 » Mon Oct 17, 2022 9:49 am

Did any of the magneto run engines come from the factory without an ignition coil. In other words just get spark from the magneto? Thanks
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Re: Ignition coil

Postby Mutt » Mon Oct 17, 2022 10:06 am

1955,56 & 57 B model Hummer and 62 Ranger didnt use an external ignition coil
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Re: Ignition coil

Postby hennesse » Mon Oct 17, 2022 11:11 am

Mutt wrote:1955,56 & 57 B model Hummer and 62 Ranger didnt use an external ignition coil


Why do you think they added the external coil in 1958? Problems with the earlier coil? Supply chain issues?
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Re: Ignition coil

Postby Mutt » Mon Oct 17, 2022 11:19 am

there was no such thing as supply chain issues in 1958. The reason for the external coil was that in 1958, US DOT mandated ALL vehicles sold in the US must have a brake light. No Hummer from 1948 to 57 came with a brake light switch unless you ordered it that way or the dealer installed it or you bought the kit and installed it yourself. NO 1955-57 B model ever came with a brake light switch. When you added a brake light switch to these models, when ya hit the rear brake, the power required for the ignition would go to the brake light and kill the ignition.
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Re: Ignition coil

Postby pumpguy » Mon Oct 17, 2022 11:27 am

That was the reason for adding the extra set of points and external ignition coil. The 55 - 57 B models the ignition was a completely separate circuit from lighting. The single lighting coil didn't have enough output to power the headlight and stop light too.

Similar problems exist on Kawasaki's KDX 200. The solution there was to either re-wind the lighting coil for extra output or replace it with a higher output coil. Another solution was to put a resistor in the tail light circuit and bypass the resistor with a brake light switch when the brake was applied. This changed the brightness of the taillight.
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Re: Ignition coil

Postby Emerica1975 » Mon Oct 17, 2022 2:48 pm

So I purchased a magneto setup that has two coil windings in it and two sets of points. So as long as I’m not running a brake light can I use it without an ignition coil? Or are there more than one style of magneto.
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Re: Ignition coil

Postby Mutt » Mon Oct 17, 2022 3:29 pm

There are 2 different magnetos. If the coil on the bottom as a spark plug wire coming out of the back side of it. yes
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Re: Ignition coil

Postby pumpguy » Mon Oct 17, 2022 3:59 pm

Please keep in mind I don't have a Hummer anymore, and haven't for many decades. I do have a magneto from a 55-57 B model converted to fit on my 250 Maico to provide magneto ignition and some direct lighting.

That said, and as I understand, the magneto set up you describe is the later style with two (2) primary LT coils and needs one (1) external HT ignition coil. It also has two (2) sets of points. As I understand this set up, one set of points times the ignition while the other set steals current from the ignition LT coil to power the stop light when needed.

The 55 - 57 B model magneto ignition coil is a primary / secondary type coil with the HT spark lead coming directly off, resulting in a completely separate circuit which has no relation to the lighting circuit. This is the same arrangement as an old breaker points ignition engine like a lawn mower or outboard motor. In fact, this same primary / secondary coil is also used in some old Mercury outboards.

Hope this is helpful.
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Re: Ignition coil

Postby Emerica1975 » Mon Oct 17, 2022 4:22 pm

Thanks for the information. When I get ready build the magneto style engine I guess I’ll have to look for a coil with a spark plug wire coming off of it.
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Re: Ignition coil

Postby pumpguy » Mon Oct 17, 2022 4:45 pm

If you can't find one, let me know. Most Harley OEM primary / secondary ignition coils have split insulation covering exposing the windings. I have repaired mine with epoxy coating, and seems to work okay.

I have a new coil from a Mercury Outboard that will fit and work. Only difference is the lead for the condenser is different so a bit of extra wire would be needed.

Originally the OEM coil has the HT lead tab coming out the back side, as installed. There was a special boot that covered this connection and was held in place by the magneto frame. That boot is probably unobtanium now but with so much stuff Mutt has, I wouldn't doubt he has one.

I would have to look at my coil to explain specific details. Its been a while since I've dealt with these.

Good luck.
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