Yup, as ram3500-RCU says... 95% of problems people have due to inverted engines stem from poor preflight...

Either they've left the throttle too open while priming, causing hydro-lock, or they have misadjusted their engines.

Our planes fly just fine upside down once in the air, running on the ground is really no different, except for starting proceedures.

Some people will clamp off their carb supply line, while fueling to further guarantee no hydrolock with an inverted engine...

... a good idea if you do not use a filler that does this for you.