Carter,,, there is such a word called "Stoichiometric"
Now that word is what is Known as the "theoreticaly" Perfect mixture
Fuel & air mixed together in certain amounts to creat that "Theoretical" particular "perfect" mixture ratio, to suit any given engines needs
One engine will differ in it`s needs in regards to the mixture ratio to another,,, depending on a whole pile of goodies
However,,, we don`t live i a "Perfect" world & as it happens, In the real world< we find that the "stoichiometric" mixture is "Too" lean & usually a tad more fuel in the mix will work far better,,, so ,,, a tad richer than the "theoreticaly perfect" mixture is just right
But ,,, if you were to be "TOO" rich, then yes there is a certain amount of long term damage that "CAN" occur,,, & obviously "TOO" Lean can cause damage too
In saying all that, it is often better to error on the rich side when setting up fuel/air mixture ratios simply because a SLIGHTLY LEAN mixture can often cause running problems , cughing, spluttering, running hot etc etc etc , "Compared" to a Slightly rich mixture
so,,, (as a rule of thumb) a guide if you will---> There are a few simple ways to determine how rich or lean your engine is running--> you can take the spark plugs out & check their colour,,, Black sooty is too rich ,,, white is too lean,,, as stated above it`s best to run a honey brown colour,,, you can also see the colour in the end of the exhaust pipe , white-ish is too lean,,, black is too rich,,, grey is nice
But,,, the fuels we now use (as compared to about 10 years ago) do tend to burn a darker colour & it`s become a little more difficult to make a mixture reading purely from a plug & pipe check,,, so there are "Gas Annalysers" in most (some) workshops these days which plug into the tail pipe & they take a reading which helps the tuner to set a nice fuel/air mixture
Have that done & you should be sweet
The amount of Damage from "Over-rich" situation depends on how rich it is & for how long it`s been running too rich & if the oil has been changed in the mean time
hope all that helps,,, if it doesn`t then sorry for the long dribble
