We HAVE NOT solved the mystery. We did get temps cool enough to fly this winter. Cyl 5 & 6 still heat up on climb out to around 340 - 350.
We contacted a gentleman in England who sent us his "patterns" for a plemun that he says, "will take care of your CHT problems" - it IS a pretty slick set up. Also have pics of another plenum installation from a fellow member of the Yahoo Group "jabiruengines" that seems to work for him. We are also looking at the SONEX Jab 3300 Baffles (www.aeroconversions.com). I DO NOT believe we will ever get there using the Jab supplied baffles - I could be wrong.
If you would like to see the pics I have just let me know.
I wish you the all the best with your project. If you ever get the chance to visit the Zenith factory please take the time to stop by our builder assist facility too. We are their newest and nearest builder assist facility and like to have visitors. We are right here in Mexico, Mo., not far from the factory.
Custom instrument panels are now available directly from Zenith Aircraft Company exclusively for Zenith builders and owners. Pre-cut panel, power distribution panel, Approach Fast Stack harnesses, Dynon and Garmin avionics, and more.
Developed specifically for Zenith builders (by a builder) these videos on DVD are a great help in building your own kit plane by providing practical hands-on construction information. Visit HomebuiltHelp.com for the latest DVD titles.