I do believe itīs worth making adjustments to make your engine user friendly.
I agree with that. The advance mechanism would make things better in this application.
I didnīt know there was a lot of different advance systems in VW magnetos. Most of the ones I have seen have been Vertex Scintillas, only with different badges(Scintilla, Hunt, Zig, VW/Audi). But I obviously never opened them so maybe you are right about that Chris.
I've heard two conflicting reports, both from Joe Hunt. One was that you can tune a magneto to have the same type of curve as a conventional ignition advance. Another said that the advance won't be all that stable--it's basically static or advanced and you don't have THAT much adjustment range.
For all I know they could offer more finite adjustment than an advance mechanism in a conventional distributor. I was really puzzled when we disassembled a mag for the first time. The 'weights' consist of brass plates cut to different profiles. Each plate had a different weight and profile (going by faint memory here I think the heavier ones had a profile that advanced the curve less than the lighter ones that advanced the curve more). The key would be to have a stack of those plates on hand to tune the curve and that's something beyond most hobbyists' reach.
As for the low advance set in many mags, could this be because they were made for either an industrial or aircraft engine which operate at a constant rpm? Just a thought.
I certainly think so. My industrial mag has 16 degrees all in by 1,800rpm. If you think about it, the engine that mag was on would operate at a static speed likely around 3,500rpm. So really the advance existed so the engine could fire easily.
Peter, I donīt think erratic timing is related to the mag being locked or not.
I don't either. That could be a host of other issues. For the most part a coil works or it doesn't. If it's starting to go bad it will produce a weaker spark. The Vertex coils usually fail by leaking their potting material. That gums up the insides of the magneto and can make them feel as if they've locked up.
I set my timing with a cheapo timing light and an external battery. I used to set it static with a buzz box or multimeter, but I have much better experience with a timing light and setting the dynamic timing.
Right. For external timing the timing light makes way more sense. It's far easier to use and because you can do it with the engine running you can check the advance curve and how consistent the timing is.
The buzz box really exists to set the magneto's internal timing. This is a little beyond my experience as I've only watched someone set a mag internally but the upper and lower components within a Vertex must be adjusted so they correspond. That's the primary function of the buzz box. You can statically time the mag to the engine with the buzz box but at that point it's hardly different than an idiot light used to set static timing with a conventional distributor.
PS. The observations about plug wires and spark plug gap are interesting. I always ran stock Bosch carbon wires with resistor. The engine fires right up every time. Good spark if you test the mag out of the car by hand. I tried once to change the gap from standard 0,028" to 0,018 and it made no noticeable difference. I run NGK D7EA plugs.
Possibly you had an application that really didn't warrant a mag.
Conventional inductive-spark ignitions produce enough energy to maintain a spark in 'normal' operating conditions. However, they don't produce a spark with enough pressure (voltage) to maintain a spark in high-turbulence applications--the spark literally gets blown out. Making matters worse, increasing speed reduces the coil's saturation time. That's a serious hindrance because a conventional ignition is limited to whatever the charging system offers.
A mag is really no different than a conventional battery-operated ignition. The difference lies in the power source. A magneto has an internal dynamo and because it doesn't feed the rest of the system its output goes unregulated. So as the magneto's speeds increase so does its dynamo's voltage and amperage. The saturation time decreases with engine speed but the primary power side has more pressure behind it to saturate the coil.
A magneto really isn't necessary until the speeds get intensely fast (like beyond 8,000 rpm) and effective and dynamic compression ratio gets really high. Even in most cases a CD ignition can do the trick. But a CD has a drawback: it merely increases the voltage without increasing the amperage. The resulting spark has a lot of pressure (voltage) behind it but not a lot of energy (amperage). In that way a magneto will beat up a CD ignition with its own book bag and steal its lunch money.
But I won't deny the other appeal of a magneto. It transforms mere mortals into gods, even if by looks only. They're seriously cool looking.
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