Scratches on spark plug ground electrode

[Scuderia]

I scratched my spark plugs' ground electrode using the gaping tool. The one with the wire. Are they safe to use? Will they cause hot spots and knock/detonation/pre-ignition? I sanded the outside of the ground electrode a little bit to remove the sharp edges from the scratches, but there are still scratches on the inside of the ground electrode.

Should I throw them away? Not really worth it all if they could damage my engine. Don't care if they're expensive iridium plugs. Any tool recommendations for gaping spark plugs, that won't scratch the ground electrode?

 

[berniedd]

How old are the plugs? If well within 100,000 miles I'd reuse them again. Just make sure you haven't touched/damaged the inner center electrode where the iridium is. It's a hard but very brittle substance. And that the gap is correct (0.043" or thereabouts for most cars).

Hint: I never use a gapping tool for spark plugs. And never bend the ground electrode in an outward direction. Since wear makes the spark gap bigger, I just tap the center electrode squarely and inwards repeatedly towards the center electrode with a wooden object, and verify with a feeler gauge after each tap if I've reached the correct gap. Tap lightly, I don't want to have to bend the ground electrode outwards should I make the gap too small.

 

[mjoekingz28]

Manufacturers suggest not gapping iridiums. At the parts house I started to check the gap on my plugs (supposed to be .040 but i stoppedmatm.025) because i thought back to that recommendation and just kind of trusted the plug maker and the parts house to be correct.


Ditch it or put it in the mower.

 

[berniedd]

Yes, they recommend not regapping plugs. But I suppose this is to keep the uninformed from damaging the plugs themselves. So long as you know what you're doing, I believe you should be alright.

Again, what I do is always tap the ground electrode in, not bend it outward with a tool, which can damage the center electrode or its insulator. The object is to narrow the gap to normal specs in a slightly worn plug. If it is too worn, I replace the plug.

 

[mjoekingz28]

Why do they make it so easy to increase the gap, but near impossible to reduce it? For those who 'use all the plug' it would make sense to be able to take it from .050 back to .040 after pulling and checking them after, say, 50k.

 

[Tegger]

Originally Posted By: Scuderia
Any tool recommendations for gaping spark plugs, that won't scratch the ground electrode?

If you're "scratching" the electrode, then you're doing it wrong.

I have posted this YouTube video at least six times so far. It's from NGK, and tells you how to set your plugs properly.