Can someone please help me to understand the concept of ignition spark advance as it pertains to performance?

Generally, does more advance increase performance (assuming you do not detonation issues and the engine can handle the timing)?

Does more advance have an affect on engine temperature? My car seems to run best (fastest) at around 36* total (initial + centrifigal) timing, but it also seems to get the engine hotter than when it has less total timing.

Thanks, this has always confused me.

 

First of all, more advance does not necessarily increase performance, too much advance will actually degrade performance. You can reach the point where the fuel mixture is not compressed enough to sustain combustion or is actually trying to fire the engine bakwards. What you need is the right amount of advance for you particular engine, fuel being burned, an load conditions. The idea is to ignite the mixture early enoungh so that there is enough time to burn all the fuel during the power stroke; however, if the spark is too early the fuel will start burnig too early in the compression stroke and push back on the piston & cause power loss.

The faster the engine rotates the less time is available to burn the fuel, that is why spark is advanced as the RPM increases.
Modern "fast burn heads" requre less spark lead, and this in conjunction with better design allows them to generate more power than the old style heads.

Compression ratio, head design, and fuel used, and engine load determine when prignition will occur. Too much spark advance will increase cylinder pressure to the point where the fuel charge will detonate insted of burning.

Part throttle operation can tolerate more advance and this yields better fuel mileage, this is the function of the vacuum advance. At WOT the vacuum disappears and the vacuum advance is not present.

In general if the spark is retarded the engine will run hotter, mainly because when the exhaust valve opens the fuel is still burning hot and the burning mixture is dumped out the exhaust. This causes a power loss and all the wasted heat serves to heat up the exhaust valves, ports, and heads. Evntually burning the ehaust valves and valve seats.

Each engine, even if built the same, has its own sweet spot regarding spark advance, so it is a good idea to experiment.