RE: GMS 76 - Which Glow Plug?
Well, since you ask, I will recommend you get a bottle of castor oil from your LHS and add 4-6 oz to your first gallon, which can be either all castor lube (hard to find these days) or at least a blend of castor/synthetic. Ringed engines really need some castor in their regular diet, and especially so for the first gallon. As Ed says, run the first few tankfuls definitely rich; then after maybe 20-30 minutes of running, lean it out over several flights to 8000, then 9000, then 10000 rpm. As soon as the engine sings with a steady note, and with enough thrust to pull the plane, you can put it in the air--but be sure you have your low end set for a slow enough idle to land with. You will probably notice improvements in power over the first 5-10 gallons. My ringed engines seem to get better every year. I run them out of fuel at the end of the day, and work 10 drops of oil into the bearings.