# Piston trip igniters



## Barnbikes (Dec 21, 2015)

Has anybody built a model engine with piston trip igniter?

Was looking at an old Patent drawing and the engine had this on it. I understand the concept of less moving parts but it puts ignition after TDC. Can't believe the engine would run very well.


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## Ogaryd (Dec 21, 2015)

I believe Henry Fords original quadricycle used the piston trip igniter, it seemed to run OK, I've not seen this used in a model but would be interesting to try.


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## idahoan (Dec 21, 2015)

My Pacific engine uses a piston trip ignitor.
http://www.homemodelenginemachinist.com/showthread.php?t=17832

Sadly I haven't finished it yet; but I know that it will run on the ignitor because my buddy built one and it runs real nice!

Dave


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## Barnbikes (Dec 22, 2015)

Not very good picture but here is the patent.


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## kadora (Dec 23, 2015)

Good idea
How it works ? In cylinder electrode in contact with piston serves as switch for ignition coil
or between electrode and piston jump sparks from ignition coil?


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## Charles Lamont (Dec 23, 2015)

Barnbikes said:


> I understand the concept of less moving parts but it puts ignition after TDC.


Are you sure?


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## Barnbikes (Dec 23, 2015)

Charles Lamont said:


> Are you sure?



Spark would happen when points broke open. Which would be after TDC.


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## idahoan (Dec 23, 2015)

What if the points were normally closed and the piston opened them? A switch (spark saver) located somewhere on the engines linkage would only allow current to flow just before the points opened; thus saving the battery and coil?

Just some thoughts.
Dave


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## Barnbikes (Dec 23, 2015)

In the drawing the pin on top of the piston is half of the point set.


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## idahoan (Dec 23, 2015)

That would complicate things; I guess I was thinking of a two point system.

Dave


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