Setting up an ignition system

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Hi folks!

Can anyone confirm that a motorcycle coil, a briggs condenser, a spark plug boot and some 14 gauge wire is about all i'll need to set up an ignition system? I've done some research and I think I understand the principles, but I'm a noob. I used to have a model T buzz coil on it but it's burned out (I think the ground connection was faulty). Do I need any sort of resister to lower the voltage?

I would greatly appreciate any advice here; I'm not familiar at all with electrics so this project is a little daunting.

Thanks!
-Will

P.S.
The engine that this set up will go on is a (semi accurate) replica of Henry Fords prototype engine (built as a science project). It shouldn't need crazy amps.

 

[Philipintexas]

I've done a number of hit-n-miss engines and used model-T coils on some. A small motorcycle coil is a good way to go, but a better spark can be obtained by using a "momentary-on", 12 volt automotive relay ($5-6) instead of the usual way of triggering the spark. A coil needs quick energizing while the contact is made, and a single spark occurs when the contact breaks. On a slow RPM engine that doesn't always work well. Using the relay, the coil gets energized/sparks MULTIPLE times as long as it's energized. The relay functions like the magnetic on/off switch on the model-T coil to rapidly "make/break" for multiple sparks while energized. I strive to get engines to run as slow as possible and this enhances the multiple sparks while the contact is closed. There are also some electronic systems available.

 

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Thanks for the reply!
The engine does run at rather low rpms... (more because of its faults than its stability, lol). How would I replace mechanical points with a relay? The existing points are pretty simple, just an arm that contacts the cam. (picture below, you can see how they're precisely calibrated with some cardstock )

W

 

[deverett]

If you are looking for a relay, eBay 261841203228 are some suitable if you can't find anywhere else.

Suitable circuit using these relays:
View attachment El Cheapo Buzz Coil.pdf
View attachment buzz coil rev 3.pdf
Same circuit, second attachment has the layout shown pictorially.

Dave
The Emerald Isle

 

[Philipintexas]

The EL-Cheapo looks like mine. On your engine the contact point is turning at half the engine RPM which is really too slow for good coil operation. BUT, It works perfectly for the el cheapo since you will get a whole cascade of sparks while the points are making contact. Take the diagram to any auto-parts store and they'll have the relay. It's a little over 1" cube, so it's easy to hide. Oh, one more thing, while testing, the thing will knock your socks off if you get grounded!! Something like 50,000 volts!

 

[deverett]

... Oh, one more thing, while testing, the thing will knock your socks off if you get grounded!! Something like 50,000 volts!

That would make your hair stand on end all right - if you have hair that is!

Dave
The Emerald Isle

 

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Well, I wired the motorcycle coil up with condenser (from a Briggs I think) and a 6 v battery and, although I could see sparks around the points, there was no spark at the plug when I turned it over. I double checked all the wiring but eventually decided just to slap on the old buzz coil (which had stopped buzzing). Weirdly enough there was a spark.
Does this make sense to anyone? Why would a non buzzing coil still produce a spark (and a blue one at that)? Granted I don't really understand much about coils....
Also, any thoughts on why the coil didn't work? I'm wondering if the 6v isn't enough voltage.