On the link
HERE there a section under "Ignition Tuning" called "
Spark Map Tuning Basics". It is actually the only section under Ignition tuning. Either click the blue link at the top of the page or scroll down towards the bottom of the page. While your at it though, go ahead and read the contents of the entire page. There is plenty of info to take in and utilize while you are tuning. It will make you feel stupid numerous times before you gain a good grasp on things.
Ignition timing is the "time" at which the ignition system is fired in relation to piston/crankshaft location or position which is measured in degrees. Timing advance refers to spark occuring BTDC (before top dead center) and timing retard is spark occuring ATDC (after top dead center) although it is also used to describe the lessening or "retarding" of total ignition advance. Ignition advance allows the air/fuel mixture to reach maximum cylinder pressure ATDC and will ideally occur by 20 degrees ATDC for dah mos horsepowers yo! So 30 degrees of timing advance means the spark is being fired at 30 degrees BTDC in relation to crankshaft rotation. There is sooooo much more to it than this, but you probably get the basic picture.
So now it's easy to see why finding out the exact spark angle was so crucial. If the spark angle setting is off in MT your entire spark table will be off by however many +- degrees the spark angle is off to the true spark angle. It's now a matter of configuring a competent msq for the rest of the guys to load up just to get things running and ready for tuning.
