OT - another high/low tension magneto thread with 1906 expanation.

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Model T Ford Forum: Forum 2014: OT - another high/low tension magneto thread with 1906 expanation.
Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Tuesday, January 14, 2014 - 03:21 pm:

The other thread was getting a bit long. This from "Automotive Topics", December 22, 1906. This article covers 1907 cars exhibited at the New York show:



Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Tuesday, January 14, 2014 - 07:07 pm:

Rob

I believe you have an article written by a journalist covering the auto show who doesn't fully grasp the differences between the high and low system. Both systems require a coil to step up the voltage at the plug. One system is self contained on a single unit (high) the other is comprised of separate components.

There just isn't any real way to jump the plug at low voltage across a gap of .030. Respectfully.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Craig Anderson, central Wisconsin on Tuesday, January 14, 2014 - 08:09 pm:

Low tension ignition is a function of current.
A coil wound with heavy wire is used to provide a significant increase in current when the field collapses.
High tension is the opposite being a function of voltage where a secondary coil wound of thousands of turns of fine wire is used to produce a significantly higher voltage than that applied to the primary.
I don't believe I ever saw an ignitor engine that runs over 600 rpm.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Wednesday, January 15, 2014 - 02:12 am:

Thanks for the explanation. I like the fact the article lays out the cars using low and high tension magnetos. Is there a definitive "one is better than the other" in regard to low or high tension mag?

Rob


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Wednesday, January 15, 2014 - 07:48 am:

Either can be fine if in good shape and adjusted properly. High tension mags are notoriously expensive to have repaired and usually dead when you find them on an old car. Often it is just bad points, but how many people (besides me) work on their own? How many people know how to adapt a modern set of points to an obsolete old distributor or magneto?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Wednesday, January 15, 2014 - 07:59 am:

I should also state that an HT magneto is more accurate cylinder to cylinder if timed properly and not worn out.

A low tension magneto (except a Model T) would depend on a timer to provide spark event timing, and depend on a multitude of probable differences between coil point settings, capacitance of the four coils, etc. to determine precise event timing. While someone like RV Anderson or me could work like crazy and make everything as close to everything else as possible, it still probably would not be as accurate. For sure back in the day it would have been OK when new but a bear to fix when it was in service after a few thousand miles.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Craig Anderson, central Wisconsin on Thursday, January 16, 2014 - 03:20 am:

Low tension systems have nothing in the circuit other than a power source, coil and breaker points INSIDE the cylinder/cylinders and are typically tripped off via linkages from a cam lobe.
I've never seen an engine with more than two cylinders which uses make and break ignition.
Aside from a hot tube it's the simplest system there is and extremely reliable when used on engines which typically run no faster than 600 rpms.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Nebraska on Thursday, January 16, 2014 - 09:27 am:

Another description of some ignition systems. This was printed in the "The Motor World", New York Auto Show car review, January 1906. It lists some cars using "make and break" ignition system. Maybe a matter of semantics, would terminology have changed? According to this, Simms/Bosch made both a "low tension with make and break igniters" and a high tension (bottom of page) magneto.

The La Coste magneto was another mag Ford considered when choosing the magneto for the Model K. Both Models N and K had La Coste timers (in some instances, and our K still has that timer).


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Thursday, January 16, 2014 - 01:01 pm:

Craig,

The Wright Flyer had a four cylinder engine with make and break ignition. I'm not sure of the rpm though.

Your are right about their simplicity. At least from an electrical standpoint. Mechanically, they are a bit more complicated, what with the linkages required to open and close the points. One thing that has not been mentioned is closing the points. Batteries would not last long if the points were allowed to stay closed until the spark was needed. These systems typically had the points held open, then momentarily closed to (For lack of a better term) 'charge' the coil, then quickly opened again to produce the spark.


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