Cylinder 8 not firing

Trevor B said

Put a new plug on the wire and got a spark outside the hole.
Then installed the plug and still no firing of the cylinder.

I do have a spark.

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Not really..... being able to fire a spark plug gap in open air is meaningless. The spark voltage needed to fire a spark in a compressed fuel-air mixture is many times higher than in open air. So, it can fire fine in open air but not at all in actual operation. You have MAYBE proven that the spark plug can fire, but not that the plug wire is OK. So actually swap the plug AND wire with another set from another cylinder. Or, connect the #8 plug wire to a screw driver and lay it 1/4"-to 3/8" from metal and see if it jumps a gap of that size with a nice blue spark.

Your spark may in deed be fine but you just have not proven that yet. Then move on with other other checks.