Thanks, Guys, for the replies. I mixed a batch of 78% of 93 octane gas and 22% castor, and shook it up good. I walked out to the test stand area and fueled her up... and the castor was already re-coagulating in the bottom of the fuel bottle. The engine ran, with a battery connected to the glow head. That batch was gone, so I mixed another batch of 1 part model fuel, 1 part 93 octane, and added .2 part castor. The fuel ran without the battery connected, but ran much slower, at 5200 rpm max, w/ or w/o battery. Not enough power developed to fly my plane, I'm affraid. Our flying field is closed due to mud and thaw, but my test area here at home is 'open' for testing. Looks like another 'good idea' has been shot down. I'll end my testing before I bust a rod or crank pin.