Originally Posted by HAL9KPCM

Here.. I looked it up: http://en.wikipedia.org/wiki/Ignition_timing

"Timing advance" refers to the number of degrees before top dead center (BTDC) that the spark will ignite the air-fuel mixture in the combustion chamber during the compression stroke. Retarded timing can be defined as changing the timing so that fuel ignition happens later than the manufacturer's specified time. For example, if the timing specified by the manufacturer was set at 12 degrees BTDC initially and adjusted to 11 degrees BTDC, it would be referred to as retarded. In a classic ignition system with breaker points, the basic timing can be set statically using a test light or dynamically using the timing marks and a timing light.

In the example, the spec is 12' before TDC, if you put it to 11, it is firing later than spec, thus it is retarded. If you put it to 13, it is firing before spec, as such, advanced. In my own example, I'm using TDC as spec for example purposes only, you go after TDC, it's retarded, before TDC, it's advanced.

Originally Posted by kip51035

Sorry "Brad B" , You are wrong! Advanced timing means it is sparking before it gets to top dead center and if you do not spin the prop fast enough it will run backwards. Retarded timing is when it fires after top dead center, which some engines do to make them easier to start. After it starts they use various means to advance the timing. At full RPM some engines are sparking at 30 deg. before top dead center. You have to set your timing with the specks of the ignition module. It might not be the stock module. Just set the pickup lined up like the instructions say at the proper degrees from top dead center and the rest should take care of itself. Improper mixture will sometimes cause an engine to back fire and run backwards. You can check the timing marks by inserting a screwdriver through the spark plug hole and rest it on top of the piston and rotate the engine until it is the farthest out of the hole, then check the top dead center mark. There should be a timing mark Just before the engine gets to top dead center in the direction of normal rotation. Check the magnet and pick up for rust and metal filings.