A miss developed on my '69 Roadrunner (stock 383 engine). Upon investigation I found #4 spark plug wire dangling loose. The plug terminal was missing--not on the plug or in the plug boot. Then I noticed the plug was loose and I turned it out by hand. Then the real shocker--the center electrode was completely gone. Anyone else ever seen a plug fail like this before? Do I need to worry about debris from this failure in the combustion chamber? I drove the car back home (about 10 minute drive) after I first heard the miss. Any advise would be appreciated. Thanks.

Any damage that might occur, would have on your way home.If you don't have a scope available, try a new plug and monitor how the engine runs. The small parts from the origional plug "probably" exited the engine on your way home. I had a wing nut do that, I could hear it shoot through the header on its way out.

WOW WOW WOW

You would probably hear it rattle if it was still in there. A piece of old weld off a egr block in the bottom of a sb intake fell in my motor once. Sounded like hell and made all sorts of marks on top of my piston. Fished it out the spark plug hole with magnet. Point is if you hear it, its still in there, and if it went in that way it can come out that way.

Do you have any freinds or enemy that would mess with you by doing that If that is completley out of the question install a new plug and go for a drive, 15 to 20 miles at normal driving speeds and then look at the new plug, if it looks good, not shiny at all, drive it. If it is shiny, that is oil, you have a potential problem, sorry I was riding with a freind a long time ago in a two year old 3/4 ton Chevy 350 C.I. 4 WHD when the complete electrode blew all the way out of the AC brand OEM plug, it was stuck in the spark plug wire end, it made a heck of a bang and then was spitting the compression out of the spark plug body. We stopped and look at it, drove to a parts store and put a new AC spark plug in of the same part number and drove on for another 150 miles to get home with no troubles

I think Cab_Burge is right, it probably blew OUT. If the wire was dangling instead of still stuck on the porcelain I would bet it never entered the motor. Reinsert as previously stated and see how it goes.

It looks like another Champion Quality plug. Had two do that years ago, the tips were still in the plug wires, could slide it right back in and gap at .035 like nothing happened. Nothing ever made it in the engine to cause dammage. Switched to Autolight the next day.

The remainder of the plug looks good... no oil on it... wow!