Tightened up the gap and it runs great. Took some begging to get my wife to come hold the flashlight so I could get a tach reading. With no muffler I was getting 6600 rpm on a 20x10 Top Flight Power Point wood prop. Not as much as I would have liked to see. Thrust calc says just over 3hp. How does this prop compair to others? Is it worth trying another prop type/size? Engine has awsome compression and a giant carb. Short of tuning the carb some more I don't think I am going to get much more. I would want to see at least 7200rpm to make it worth it. Will try some more tomorrow. Carb is hard to tune because the needles point toward the prop and I can't get a grip on then to turn without a screw driver. I have to kill the engine to make adjustments. Will try again with the stock muffler but I think it chokes it off quite a bit. Hard to get a good idle with no muffler.
As a side note I was watching the exhaust with the muffler off. At low rpm I see a pretty large blue f'lame, at high rpm the flame turns yellow and gets much smaller. Does this mean anything?