[MiracleMax]

Ignition timing encompasses two things total advance and intial timing which can be retarded or advance.

Initial timing is set via its relationship to the position of the piston and top dead center (TDC). This is affected by a great many things; quality of fuel, combustion chamber design, engine operation tempeture, fuel homoginezation, ect. and in the case of Ford the assumed operating parameters of the engine. Ford apparently uses a conservative ingnition seting to avoid possible damage to the engine (I assume due to the quality of available fuels and the tinker factor).

Anywhosit that aside, intial timing is usually set so that the ignition fires sometime before top dead center giving the charge time to burn across the cylinder creating maximum pressure on the piston as it crosses over from top dead center to after top dead center (IIRC its like 4 to 6 degrees after TDC you want maximum pressure on the piston). Again the amount of intial advance depends on fuel type and engine design. Typically a more efficent design combined with fast burning fuels requires less initial advance.

total ignition timing is the range of advance that the ignition system can move through so that precise timing can be adjusted based on speed and load (basically). As engine speed increases it requires more ignition advance to precisely fire the plug so that maximum pressure can be placed on the piston. The chief reason is that the psiton is moving much faster and the charge doesnt have as much time to complete its burn as the piston approaches TDC and then begins to move away.

I once had a shop teacher that swore up and down (and probably to his grave) that no engine could rev past 6000 rpm. his reasoning was based on the notion that gasoline burned at a constant rate (wrong) and that it took a defined amount of time for a air/fuel charge to burn no matter what type of engine if it was using gasoline.

I'm no guru and he might have been right about a single droplet of regular gas but he was completely wrong about the the time it takes to burn across the cylinder.

Physical size of the cylinder has alot to do with this, so does the the combustion chamber shape and the piston shape. As well as the quality of the air/fuel mixture (small droplets burn faster and big droplets burn slower or not at all). Take a look at an F1 engine, very small bores with extremely compact combustion chambers.

Want the best sort of combustion chamber, make it a small bore/long stroke hemi with a centrally located spark plug and a flattop piston.