Howdy
I have two of these engine and one worked just great out of the box.i mounted it on its side and it worked just great no problems what so ever.
The other i installed it inverted and it was a horror storey.
In the end i installed it on its side and after that it works just great.
I even changed tank locations just to try other things.now i run duel tanks so i can get the tanks up higher.
Hope this helps
Take care
Frank