Limited Coils?

[Ozarker]

So, by shaving the key we can advance the timing, and still utilize the programming set in the coil . . . right? Or, would the programming recognize the increase in timing and seek to return that to the programming, thus limiting, or negating the advance on the key?

Questions, questions.

 

[Terry Syd]

Sure, we could shave the key and still utilize the programmed module, in fact we might want to shave the key. The module with the programmed ignition curve still has to be positioned correctly in regards to the flywheel magnets. So, even if we had a programmed module, we might still pick up some power by tweaking the position as there are various manufacturing tolerances involved. Heck, on my 029/390 the stock factory tolerances allow a timing between 23.5 to 28.5 degrees BTDC. That is 5 degrees of 'sloppiness' in setting the timing - definitely not designed for performance.

 

[XP_Slinger]

If I understood electronics, I'd love to pull one apart, then figure out the engineering, the program, and how to re-program. Alas, others will get to make millions from that endeavor. Prime business opportunity here for some adventurous person.

Here ya' go, Terry. I had to do a screen-shot, crop, then save, then crop again, to get it.

View attachment 18327

It says "confidential" in the corner...lol.

 

[Ozarker]

Sure, we could shave the key and still utilize the programmed module, in fact we might want to shave the key. The module with the programmed ignition curve still has to be positioned correctly in regards to the flywheel magnets. So, even if we had a programmed module, we might still pick up some power by tweaking the position as there are various manufacturing tolerances involved. Heck, on my 029/390 the stock factory tolerances allow a timing between 23.5 to 28.5 degrees BTDC. That is 5 degrees of 'sloppiness' in setting the timing - definitely not designed for performance.

I thought that's how it ought to work. Looking at the graph, there's a 3° - 5° range of acceptable performance at given intervals, i.e., starting, idling, max power, so it seems as though it could be advantageous to shave the key a bit, besides the placement of, and relative position of the coil to the flywheel. I'm sure this graph is a generalization, or perhaps unique to one model, but it still conveys the idea. With a so-called unlimited coil, that increase in performance also ought to increase the max rpm of the saw, within limits of the carb, seems to me.

 

[Ozarker]

It says "confidential" in the corner...lol.

LOL I started to crop that out, but decided that Stihl needed the credit for it. Besides, it's still "confidential," just among a wider audience than before.