Nice write up!
It's good to hear about the difference for your engine with P-mags.
I have a pair of 113 series in my Superior IO-360 in my -7 and LOVE them!
Since the last mandatory update (Sept 2008) they have been performing just great!
I've already bought a pair of 114 series for my next -7 and asked Brad last week if it was any more updates on the horizon, and the time interval for plug-change and here is his answer:
We have had no updates or changes in over a year and a half, so your units should be current.
Most customers are changing out their auto plugs every 125 hour or at annual - which ever comes first. They may last much longer, but as cheap as they are its not a significant expense. I do occasionally hear of customers experiencing roughness with plugs that exceed that mark, and after putting in new plugs the problem clears.
At Sun-N-Fun we had a couple of customers tell us they were getting better performance in certain conditions with the iridium tipped version of the BR8ES. Not sure what the part number is off hand, but it may be something you’d like to try. Previously, our reports on the benefits of iridium tipped vs. standard tip was inconsistent. They are more expensive than the BR8ES plugs but still a fraction of what the cheapest aviation plugs cost.
I have now 140 hrs and two years on my plane, (first flight July 2008) and for the last 5-10 hrs, I've noticed that the engine now needs just at tad over what it used to require for 50* LOP: FF at 23-24 litres/hr instead of 22 litres/hr at 55% power (21/2100) but as always, it runs smooth as silk.
When I lean to 22 litres/hr now, I experience a ever so slightly roughness, but it is so little, so it could as well be my own imagnation.
I always fly at 50* LOP at cruise and always lean as much as I can on the ground (just above stumbling)
After parking and just before every shutdown, I run engine at 1100 RPM for 30 sec's with the mixture set so the engine stumbles just a little. I've heard that this procedure increases the temp in the plugs so the lead will burn off, thus easing the next startup.
I'm no engine expert, but this procedure works for me: the engine always starts during the first one or two turns, cold, warm or hot.
My annual comes up in June, so I'll change the plugs then of course.
I'm using BR8ES now and I'm considering changing to the iridium-version. Anyelse using those? If so; what's your experiences?
Last annual, (80 hrs) I checked the plugs: no lead-build up and looked real fine. I rotated them from top to bottom but it made no difference back then, since the engine at that time was running just like it had been doing for those first 80 hrs.
From now on, I'll change the plugs according to Brad's recommendation.
By the way: if you REALLY want to know what's going on with your P-mags, harness and ignition-system, you might want to install the Electronic Igntion Commander:
http://www.eicommander.com/index.htm
Good luck with yours!