[ndutton]

This past week I watched a classic car restoration show on The Velocity Channel named FantomWorks. The episode included restoration of a 1917 Overland with a 4 cylinder flathead engine. Near completion it was time to fire up the rebuilt engine. Early attempts were not successful. Fuel delivery and compression were determined good which left ignition timing as the problem. The tech commented he had no information on the engine, specifically the firing order. He fell back to trial and error guessing that finally won the day.

My mind went immediately to this thread on our forum. Instead of one modified spark plug/balloon indicator, make four and thread one into each spark plug hole. Turn the crank slowly by hand in the direction the fan blade pitch indicated and record the order the balloons inflated, that'll quickly, easily and under control give you the firing order, then set the crank and distributor at #1 TDC, plug wires in their corresponding positions around the distributor* and you're done. No guessing needed.

*distributor rotation direction also observed during hand cranking