I am using a satio 150 and will use it inverted ..something new to me as well.some guys said that while inverted you can set it up with a very slight offset to help reduce hydrolock..if you are using a satio and even if your not go to their website and you'll get some great advise.what the guy said previous to me is right on ..there is a fudge factor of maybe up to 1/2 inch but why do that.otherwise as I have now learned they work just fine!! be sure to lean the idle mixture when inverted..