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Originally Posted by ewhite832ltd  Its a 1946 flathead |
A 45 or a Big Twin? Either way, the spark control works the same. Generally, you'll definitely want to retard it when you start it. Sometimes when it's warm, maybe not all the way, maybe halfway. You'll figure that out--- retarding the spark makes it easier to start without kicking back-- fires a little later when the pistons are on the downstroke. Otherwise, fully advanced is where you want to run it. On a flathead especially, running with retarded timing will cause overheating-- the nemisis of a flathead.
Running on the roads, sometimes when pulling a hill, a little retard will give you more grunt, and eliminate pinging or detonation-- but again, be cautious about too much of that because of the overheating aspect. The flatheads have an inherant 'hot spot' next to the exhaust valves, and most flatheads with a dead motor are from a piston meltdown because of that. Don't push a flathead motor; think semitruck instead of Maseratti.
You should get a manual if you don't already have one, and first thing to learn is setting the timing, static method. Once set, there's no reason to ever change it; there should already be an index mark on the timer base. The points gap will also have a minor effect on ignition timing, so be sure the points are set correctly first.
Hope this helps....
correct spark advance 
Linear Mode
