I have a Norvel BigMig .061 RC engine, and I have a couple of questions for anyone who can help.

When breaking in the engine, should the throttle be fully opened, full closed, or somewhere in the middle?

If I start with the needle valve at about 2 1/2 turns open, is closing the valve making the engine run more rich or lean?

What is the purpose of the small screw just aft the needle valve, and how should I go about adjusting it?

The muffler that came with my engine is connected by a little bent wire that goes around the engine and holds it in place. However, it does not hold it too tightly, and the muffler does not stay exactly over the exhaust. Is there something I should do about this, or do I even need the muffler?

And finally, I've read about the importance of having a pressurized fuel tank, and from what I read, I understand that to mean that the engine runs best when air is being forced into the tank, which in turn forces the gas into the engine. However, I've noticed that my engine runs best when I have the vent line on the fuel tank plugged up allowing no air to go into the tank. (This seems to work better than running the exhaust line to the top of the muffler.) What is going on here, and is that bad for my engine?

Thanks in advance for any help you can give.

-chris