Originally posted by hwflyer
I just mounted by trainer engine with plug on top but I have seen some planes where the engine is mounted sideways. Can the engine be rotated any direction on the firewall as long as the thrust line stays in the correct orientation. I assume the answer is yes since plances can fly upside down but does the orientation effect things like idleing and fuel flow?
engines can run in any orientation to the ground but they run best when upright.
when they are inverted you can have a problem with flooding the top of the cylinder which can cause it to not start at best and damage the engine at worst.
alot of times mounting and engine sideways or inverted is done for cosmetic reasons (to fit inside a cowl) or so that the carb is not too high to aid in fuel flow.
bullet when you mount your engine you want to check were the carb is going to end up.
if it is too high above the centerline of the fuel tank then you will have trouble getting the engine tuned (it will want to lean out alot when fuel gets low) too low and you will have a problem with flooding and too rich.