I'm now at the point I'm ready to put my S29 into service I think. I ran another 1.5 quarts through the engine (5% nitro 20% castor) and set it up for the best possible idle, and adjusted the spraybar a little to improve the transition some. Its still a little rich in the midrange, but I've been running the exhaust through a bucket to lower the noise and suspect the extra backpressure and old glow plug causing the non-ideal midrange. The lowest idle I got was about 2600 with a more reliable idle of 2800-2900rpm or so. I still havent peaked it, but ran it within 500rpm of peak power. I have a (albeit crappy) video of the last run I made with it. It definitely needs more run time to improve the idle and midrange, but I think it will run pretty well as-is with some fresh fuel and a new glow plug. I let it rev out to about 15,200 for a short time and feel pretty safe at 14,800rpm. I am guessing it will peak around 15,700 with the pipe untuned. How high is too high of an idle to get the idle mixture set properly? I was setting my idle mixture with the engine idling around 2900 and got it pretty close.
A question for those that have experience with the S29 - Has anyone gotten a perfect transition and nice low idle with one of these without having to adjust the spraybar or is it the norm to adjust the spraybar on these?
I plan to run it one more time with a new plug, fresh fuel, and the pipe not run to the bucket to get a final judgement but so far it seems to be running rather well.
edit: added video.
http://youtu.be/qD6tqD2CaoU