i am installing a 4 stroke engine in my biplane and i always see them inverted. is this preferable? i have plenty of room to mount it anyway i like but it will look good sticking out the bottom. better hidden that way.
i guess my question is do they run better this way? easier to start?

John:

The engines run just as well inverted as upright. But they can be more critical in adjustment.

Just make sure the tank is not too high, might be a bother to start until you get used to it, but once you get there all will be fine.

Bill.

The engine doesn't know its upside down. Even in most real aircraft with inline or v configurations, the engines are inverted. If you don't like iverted you can always mount it any way you like. Inverted means less obvious cutting of the cowl, just makes it look cleaner than a big hole in the top or the sides.

will

to answer your question, no they will not run better, assuming your carb/fuel tank line up fine in both situations. invertered are more prone to flooding and as someone else mentioned sometimes a little more finicky to set up.