The disservice that is done to novices, is to instill a false fear that forces them to cure a problem where none exists.
I've seen engines go flying off of planes, because the firewall was weakend by the attempt of a novice to drop the tank height, thanks to the hype and fear instilled by those who think they are giving good advice.
Novices fall prey to comments made here and take actions that undermine safety for NO real gain. They undertake modifications simply because they are convince by people such as Jaka, that "fuel centerline to carb height" is "absolutely critical", as in Jaka's post.
Yet this is very far from the truth.
John I suggest you try talking to the engineers that suggested those lines in the documentation of the "manufacturer with the very best and most comprehensive owners manuals industry wide". Ask them what testing and basis went into the assersion. You'll be surprised.
This was included in the manual, not because of scientific evaluations, but rather it is the result of a long passed down suggestion which in turn is nothing more than a platitude handed down time and again without re-evaluation similiar to the "fuel stays in the back of the tank" myth.
BTW: I was dismayed to see Clarence Lee purport that nonsense, which will unnerve any applied physics student as it is not based on the real world.
There are many posts here where some novice stepping up from a trainer inquires about an inverted engine installation in a plane designed for it, such as the U-Can-Do's. The "experts" are all to quick to repeat this mistake. Novices go to extremes to fix what they perceive to be a "problem" where there is none.
A typical U-Can-Do with an inverted engine mount leaves as much as a 1-1.5 inches of tank/carb height difference.
Does this make starting the engine problematic?
No unless the user has been improperly instructed on proceedure. e.g no priming, leave the engine at idle once the plane is fueled, etc.
Does this warrant ripping up the firewall to establish a new bung hole and tank mount?
No, if anything doing so runs the far more important risk of weakening the firewall.
Does this make the engine run differently?
No NOT AT ALL once it is started and properly tuned.
This is the VERY place that this information needs to be put forward.
Novices should NOT be told to modify tank heights, nor that this is "absolutely critical".
Rather they should be directed to seek the help of people who are familiar with this type of thing and reject suggestions that they MUST modify their planes.