Electronic ignition

[cmfalco]

I’d rather focus on the Brassington Modification

Have you found the issue of Cheval de Fer where that modification is described?

[Mike Nash]

Have I “. . .the issue of Cheval de Fer where the modification is described?”
Yes, or rather I’ve the article of interest, for I’ve always filleted magazines to cut the bulk to reasonable level and then filed the kept bits in various folders. Alas, in those days CdF didn’t date each page as it does now so I don’t know the publication date for the Brassington article. However, other related articles I’ve dated and in the January 1995 there’s a mention of a variation of it (by John Bateman), so Brassington was published pre that date.
To expedite things, I’ve written to the current editor suggesting that he republish the article but, of course, I’ve assumed that he has copies of these early CdFs. And I see that in the April 2004 issue, one Peter Wragg was doing it commercially, recommended by one David Jones (“the Square Four expert”) to a Huw Parsons, an owner of a 1931 ohc Four.
I’d like to get it published again ‘cos I expect there’ll be improvements in the coil and condenser/capacitor in the intervening 30 years. I eagerly await the opinion of your alter ego “Magnetoman”. MikeN.

[pete.collings]

Every club member should have access to Cheval via the AOMCC members website section, I spent many hours scanning and uploading copies going back to 1957!
I also have a file created by the late Ralph Hawkins that lists articles going back some time, but it is a large file would need some time to go through to locate the article in question.

[will_curry]

I too have a copy of Ralph's file - with additions from Roger Gwynn - and I couldn't find any
mention of the article when I looked yesterday. My intention is to process the file into a
form that could be incorporated into the website much like the KnowledgeBase and the
searchable list of Cheval article titles. However, while there are still Ariels I can ride
completion has been somewhat delayed.

[cmfalco]

I’ve always filleted magazines to cut the bulk to reasonable level and then filed the kept bits in various folders.

I do the same, adding the articles to the bespoke 3-ring-binder manuals I've made for several of my machines. I also have the same problem of locating originals of articles when the dates (or even the name of the magazine/newsletter) aren't printed.

I started with the August '96 article you mentioned in your previous post, but quickly gave up trying to find the earlier, original Brassington article. A few Vincent people did what it sounds like a few Ariel people have started to emulate, in that they republished the technical articles from their monthly 'MPH' in book form, indexed by topic and with the issue of 'MPH' noted. The original book, '40 Years On', came after -- you'll never guess, so I'll tell you -- 40 years of 'MPH'. This was followed by two subsequent supplements, the first of which, 'Another Ten Years', came, well, I'll leave you to try to guess when...

Semi-related to this is as far back as high school I took to heart something I learned from a friend at the time, that "half of knowledge is knowing where to find it." Much later I learned that this was a slight variation of the motto on the library at Florida State University. Anyway, over the years I created searchable indexes of eight motorcycle magazines to assist in finding knowledge among the shelves of my library.

As an aside, your posts prompted me to start drafting something I've tentatively titled "Aging Electricity." Not because electricity is getting old, because it isn't, but because we are.

[will_curry]

Is the article on page 18 of the May 1994 edition of Cheval the one you seek?

[cmfalco]

the article on page 18 of the May 1994 edition of Cheval

Several things Mr. Brassington wrote caught my eye:

"Last week saw me fitting my fourth magneto in only seven weeks. Two were rebuilt units from well known people…" In my case, it only took one such magneto that had been rebuilt by a well-known person for me to conclude I had to teach myself how to rebuild magnetos.

"All I pray is the dynamo keeps doing its stuff as I am now totally dependent upon the electrical system." Which is why I strongly prefer magnetos.

"Compared to the cost of having a magneto rebuilt professionally…" See my response to the first quote, which isn't about cost, it's about reliability.

Anyway, the point of this post is to examine Mr. Brassington's conversion, and his Diagram 3 is why I find it unacceptable.

The brush is in series with the points, and the next several figures show why I doubt the reliability of this connection. The upper part of next figure shows the resistance of the carbon brush itself is only a fraction of an Ohm so it, alone, wouldn't be a problem, but the bottom part shows the spring itself is nearly 4 Ω, which would be a problem.

It's worthwhile to digress at this point and show the construction of the HT pickup itself.

As can be seen, a large brass insert carries voltage and current from the input of the pickup to the carbon brush. However, note the condition of the oxidized brass at the input to the pickup. This is typical of the dozen or so used pickups I have, and shouldn't be surprising given they are essentially exposed to the elements. If the brass isn't polished, a metal-to-metal connection to it will have a resistance of many Ohms. And, even if polished, the input isn't hermetically sealed so water will get to it in the future and increase the resistance.

Moving on, Mr. Brassington's solution to the too-high resistance of the spring is to feed "flexible" Cu wire to the brush. He also reduces the length of the spring by 60%, which I don't understand since that would leave the brush assembly too short to reach the slip ring. The simultaneous requirements on the wire is that it provide a low resistance path while also having minimal effect on the movement of the brush. Even if this is achieved on the bench in the garage, I seriously doubt its long-term reliability. Further, low resistance wasn't a requirement when the HT pickups were originally designed, since even a few Ohms in series with the ~5 kV wouldn't matter. Stated differently, what is needed is a reliable, low resistance contact in the points circuit, and Diagram 3 doesn't meet that requirement. That said, none of this is relevant if an aftermarket ignition system with an electronic trigger is purchased.

A final point is that Mr. Brassington wrote "I've experienced every magneto problem in the book …. shellacking, loss of magnetism when hot, condenser failure, winding failure, oil on pick up etc etc." However, since he didn't rebuild those magnetos himself, the only way he would know the cause of those failures was if that is what the "well-known" people who restored those magnetos told him. In my view, he confused cause and effect. Although the effect he experienced was multiple failed magnetos, the cause wasn't the magnetos, it was the rebuilders.