That also explains why lovers of side-valves often experience the benefits of mixing a liter of diesel on a full tank of gas. With an engine that is made for normal petrol, the combustion is therefore faster. If you fill this engine with higher octane gasoline, you actually need the set inflammation a little earlier.In the past, you had to ask a customer during maintenance what kind of gasoline he or she used. If the customer was filling up with petrol, the ignition had to be set a little earlier.
In the meantime, with the alcohol-contaminated petrol types, there has also been a need to seriously consider whether the factory-specified ignition time is still in line with practice.
A way back in the old days is to set the ignition on time, and then to give short 'bumps' while turning the distributor cap a little until the engine starts pinging during that action.
The final approach is then just like tightening bolts: keep turning until it breaks, and then back one eighth.
It's funny, by the way, that nowadays there are a few generations of car mechanics walking around who have never worked on a battery ignition coil with contact points