Ignition Dwell Calculator

Liguori Drag Racing • Electrical

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Ignition Dwell

Check charging time against the firing interval of each coil.

Starting values are examples. Enter your measurements; results update as you type.

Method & assumptions

Sequential COP fires each coil once per two crank revolutions; wasted spark once per revolution; distributor N/2 times per revolution. The result is a timing-capacity check, not a dwell recommendation. Obtain actual dwell versus voltage and coil thermal limits from the coil or ECU manufacturer.