David, what kinds of failures are you seeing?
Good question. Some have been failure to operate. Some have been random timing. I am reluctant to post all the details as this forum jumps on posts where suppliers and their failings are exposed, and then the thread disappears.
I will say that Ross at SDS knows his stuff, builds quality gear. I have so far not seen one problem in a properly installed SDS system.
Brad the Pmag guy, at least he will support his customers, I had three 6C Mags fail all about 10-13 hours apart. I never found out what the actual failures were. This was replacing one of two LS ignitions. In the end the owner bought two slicks. There have been off the top of my head 6-8 or maybe more 4C pmags do strange things, mostly losing timing reference. Of course there are many more who have not had problems, or not that I hear about.
I have been helping a fellow down here this year that has a destroyed IO390 as a result of a dual LS going nuts on one ignition. Advanced possibly randomly from who knows where to 40-60 degrees and massive rise in CHT on all 4 cylinders. The owner repeated the exercise as he didn't believe it. Anyway CHTs recorded in the high 500's and one up to 630dF.
The only component in the engine, and I have the photos, that is reusable is the camshaft. The ignition manufacturer when asked about fixing the ignitions (before we pulled the engine and realised how bad it was) was ignoring the data (EMS and borescope) and was so dismissive and condescending even a hard-*** like me was stunned.
For clarity I have had a coil in a Slick let its guts out, crossing Bass Straits (Tasmania to the mainland - map that) so they too can fail. But as a failure per unit x hour rate, old Slicks trump the others (excluding SDS).
For full disclosure - I have no connection, no interest and no reason to support any EI supplier at all. My suggestion of SDS over a magneto is simply this. If you really want EI this is the best option by far but do realise that EI timing must be set 2-3 degrees less than the old mag number and do not use advance beyond 3-4 degrees when LOP. It helps LOP at high altitude a little. There is no HP benefit.
I do have a lot of time on the GAMI dyno and have watched hours of timing changes with real data showing the pressure traces, inducing detonation and killing it. The George Braly / John Deakin discussions over the last 10-15 years have taught me so much. I am just trying to relay what is real in simple terms.
I hope this helps.
PS: I will write up a report and photos of the IO390 episode, once the owner gets it sorted and replaced. And I find time to do it properly. There was a hidden latent secondary problem planted by a mistake of a very famous engine shop (and they are being co-operative) that was slowly destroying this engine also, but the preignition was the killer.
