Just got my Mac 28 put together and fired up, today, and I am pleasantly surprised at the initial performance I saw. APC 16X8 prop turned 7850on the first tank of fuel. I was running rich, mainly in the mid range to get the ring set with occassional run up to set the carb, more or less (I'm not spending a lot of time tuning the carb untill a bit more break in takes place). Oil is 40:1, carb is Walbro 11mm ( I bought it from Scott Ellingson a few months back), muffler from Ken Lambert. Conversion kit from Dave Carr (great stuff, everything fit and worked right).

This is going to go on a Balsa USA Sopwith Pup 1/4 scale, later this year. I need to build the 1/5 scale Sig Cub as "conditioning" for my Pup build, later.

With this good start with the engine, I am looking forward to getting it fully broken in and "tweaked". I am anticipating a bigger diameter prop for the Pup. I think it's off to a good start.

Good Job Jim....If you have access to a digital camera maybe you could post some pictures as you progress. Mac engines are really powerful so it should do a great job.

Bob...

Update: today, ran 2d and 3rd tanks (320mm), no change in needle settings, running at mainly around 4000 rpm with occassional run up, got to 8010 rpm. Changed prop to APC 18X8N, got 7200 rpm. Seems to get stronger with each tank. I'm happy with it.