Any 6 Volt coil will do?

[jadz928]

Hi everyone,
Did a quick search, didnt find the answer.
Will any 6 Volt coil work?
'29 Roadster, 6V, positive ground.
Thanks!

[Purdy Swoft]

Six volts will use a 1.5 OHM coil . Twelve volt systems often use a three OHM coil . A 1.5 OHM coil can be used with a twelve volt system if a ballast resister is used at the coil connection .

[Aarongriffey]

Do the simple thing.
Get a model A coil or go to a good parts store and gpask for a 1966 Volkswagen coil. If they ask what model tell them a bug or buss.
No extra resistors or in-line bolt on crap needed. The coil will have it built in.
The Plus or sw terminal on the coil should go to the model A ignition switch which then goes to the model A distributor.
Shot wire from your ammeter goes to the minus or distributor side of the coil.
The VW was minus ground, so you must connect the coil backwards on a plus ground car.
If you have a choice, get a Bosch coil. I have had trouble with NAPA 6 volt coils.
And I am a NAPA fan.

[Bill G]

Yes, generally so.

[jadz928]

Thanks for the responses, very helpful. I found this article on Hemmings which was also helpful.

I'm familiar with the Bosch coil as I'm into German gear as well. Gonna go with something a little more vintage domestic for the Roadster.

[30 Closed Cab PU]

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Thanks for posting the article - a very nice summary, especially like the diagram.

[rotorwrench]

The diagram of the coil internal electrics in the Hemmings article is misleading. It shows the secondary coil being grounded on one end with the other end to the high tension terminal. This is misleading. The secondary coil actually connects to one side of the primary coil near a terminal. They were generally connected to the negative side connection but this is why a polarity tester is needed. Since a person can't see inside, they wouldn't know which terminal it may be connected in with. They would never ground it through the case like that diagram implies.

[Ernie Vitucci]

Good Morning...Why not just order the correct coil from Bratton's or Bert's, Snyder's or Arizona Model A, and be sure you have the correct one. Also we need to keep the suppliers in business as they have a mutual interest in stocking what we need and the modern suppliers do not. Ernie in Arizona

[Purdy Swoft]

Some prefer a hotter performance coil . I prefer and use the Pertronix flamethrower coil . I use the epoxy filled version . The model A came with a tar filled or solid coil . A solid coil is preferred because it can be mounted as original with the wire connections at the bottom . An oil filled coil if mounted with the wire connections at the bottom can cause the upper internal coils inside not to be completely covered in the oil . If the internal coils are not completely covered they can over heat and fail . A solid coil will insure that all of the internal coils are always be covered . I use a 1.5 OHM coil on a six volt system . I prefer to use a three OHM coil on twelve volts . A 1.5 OHM coil can be used on twelve volts if a ballast resister is used at the wire connection . The resister prevents the full 12 volts from entering and burning out the six volt coil . In such cases a person would still be using a six volt 1.5 OHM coil . I personally prefer to use a three OHM 12 volt coil on a twelve volt system . A three OHM coil doesn't need a resister to be used on twelve volts . I prefer not use a resister because it doesn't look original . A resister gets too hot to touch and I would prefer not to go that route .

[johnbuckley]

Originally Posted by rotorwrench

The diagram of the coil internal electrics in the Hemmings article is misleading. ....

Gosh you're right ... not just misleading .... it's WRONG!.. so sad that inaccurate diagrams/advice like that gets repeated so easily these days .

[30 Closed Cab PU]

Originally Posted by rotorwrench

The diagram of the coil internal electrics in the Hemmings article is misleading. It shows the secondary coil being grounded on one end with the other end to the high tension terminal. This is misleading. The secondary coil actually connects to one side of the primary coil near a terminal. They were generally connected to the negative side connection but this is why a polarity tester is needed. Since a person can't see inside, they wouldn't know which terminal it may be connected in with. They would never ground it through the case like that diagram implies.

Thanks rotorwrench - did a little more reading and I see now where an automotive coil is an autotransformer, and that diagram is definitely wrong.

[jadz928]

Originally Posted by Ernie Vitucci

Good Morning...Why not just order the correct coil from Bratton's or Bert's, Snyder's or Arizona Model A, and be sure you have the correct one. Also we need to keep the suppliers in business as they have a mutual interest in stocking what we need and the modern suppliers do not. Ernie in Arizona

Because it's for a Roadster 'hop up' from the 40's. Trying to preserve what we can, and replace with period parts that were used.


Don't worry, we're giving those vendors (and more) plenty of business.

[Patrick L.]

Not necessarily. I learned that lesson long ago with VWs.
Oil filled coils don't like to be tipped upside down. So use an old tar filled or new epoxy filled 1.5 ohm coil and you'll be fine.

[Bob-A]

What Purdy Swoft said!


Bob-A

[Purdy Swoft]

Thanks Bob-A !!!

[Patrick L.]

Sorry Purdy, I didn't read any of the posts. Didn't have the time. Had I read yours I wouldn't have responded.

[Purdy Swoft]

Originally Posted by jadz928

Because it's for a Roadster 'hop up' from the 40's. Trying to preserve what we can, and replace with period parts that were used.


Don't worry, we're giving those vendors (and more) plenty of business

Period correct performance parts are cool !!! I don't know if they still have them ,but I have purchased bee hive type performance coils from Berts model A center . I prefer the Pertronix flamethrower coils That are listed at 40.000 volt out put . I can feel the boost . I use the 12 volt epoxy filled version but these coils are offered in both 6 or 12 volt , oil filled or epoxy filled . The flame thrower coils look just like other replacement coils .

[Purdy Swoft]

Originally Posted by Patrick L.

Sorry Purdy, I didn't read any of the posts. Didn't have the time. Had I read yours I wouldn't have responded.

No problem , Pat .

[katy]

did a little more reading and I see now where an automotive coil is an autotransformer

Wrong, an autotransformer has only one winding, an ignition coil has two.

[Purdy Swoft]

The spark comes from the coil .