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Hello- > I think the real weakness of the Pertronix is the virtual impossibility of > controlling the magnetic fields well enough to give consistent timing signals. > I believe what you are seeing is just normal variation of the Pertronic system. It is common (although it shouldn't be normal) variation for Pertronix, but it's not due to a fault of using magnets in general. Magnetic sensors are VERY common in engine timing applications, from distributors to FI sensors, and can give VERY accurate readings. > This has always bothered me, because it is notoriously difficult to control > magnetic fields in general, and permanent magnets in particular, plus these > sensors are working in the fringing fields of the magnets where the field > strength is a very strong function of the distance. So a small amount of radial > play in the shaft can have a huge effect on the timing. It's not as much as you think... if it were such a major problem, then the flywheel endplay of a typical modern EFI engine would play hell with the flywheel-mounted crank position sensor, but it doesn't. I've had the problem described before. If you take out the magnet sleeve, rotate it around 90, 180, or 270 degrees, then reinstall it, you'll find that the screwed up timing just follows the sleeve. It's a manufacturing inaccuracy. Take care, Shad Laws LN Engineering http://www.lnengineering.com ------------------------------------------------------------------- List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org