Ford 302 Spark Plug Gap. My 66 has a 302 in it, however, i am unsure of the year. They are 6.75 in length and i cannot find them for sale anywhere.
The spark plug gap adjustment should not be changed more than 3 times and should not exceed.008 in either direction. Points ignition can only handle so much. If your wires check out then take the sparkplug out of the cylinder and put the spark plug wire back on it and lay it on the intake manifold and crank the engine and see if it gives a spark on the gap, if it does, then you need to perform a compression test at least on that cylinder, as you could have a bent pushrod, collased lifter, bad valve, etc.