You made an excellent choice in your purchase of the Irvine .53. Irvine makes very good engines. They are best known in England, and have not as yet gotten the exposure in the U.S. that they deserve.

The 10% fuel your are now using will be just fine. The nitro content is not nearly as important as the oil content. An 18-20% oil content would be good. Synthetic or castor oil, or a combination of both is fine.

The engine will most likely arrive without a glow plug. May I suggest an OS #8 glow plug if you need one? They last a long time, are extremely dependable, and seem to provide the best idle of all the plugs I have used.

ALL engines should be "broken in" before they are flown. This permits the internal parts of an engine to match up after the machining processes from manufacturing. It's not that hard to do, and can be done on the plane if you don't have, or want to use, an engine stand. The break in process varies in time from engine to engine. The initial phase of break in can be noted as the point at which the engine will idle reliably for an extended period of time and advance to full throttle smoothly without shutting down. The advancement to full throttle also relies heavily on correct needle settings. Adjusting one needle quite often requires that you adjust the other needle as well. Especially on new engines.

For the correct starting needle settings, you should consult the manual that should arrive with your engine. You should also get in touch with the person that set up your first plane and engine and pay attention to what he does. Don't be afraid to ask him questions, that's how we all learn.

It is not possible to give you "absolute" adjusting information over the web. Too much depends on the "ear" of the person adjusting the engine, the prop used (your 11/5 will be fine), the weather conditions at the time, and other factors. The person you described as tuning your first engine sounds like he knows what he's doing.

Good luck, and have fun.

Silversurfer