If your powering your timing light from a 6v system and it's a 12v light it may fire but it probablly can't be counted on. They generally are designed witn a voltage regulator to operate between 10v to 16v.
A coil is about twenty bucks at Auto Zone tax inclulded. That is the best way to check if you have a bad coil. A resistance check only checks the continuity of the windings, they can be ok and still cause problems like arc over when they get hot. A bad coil can cause lots of odd problems especially when they are hot.
DG
