Help Analyzing Used Spark Plugs

Lighting of the electrodes leaves a bit to be desired, but from what I can see the deposits look OK, maybe a bit on the old side. How many miles on the plugs?

IMHO, cleaning / regapping a plug is false economy -- they're not that expensive, and if a piece of the plug breaks off in the engine, the damage is going to be way more expensive than anything you just saved.

I'd just replace 'em with the equivalent NGK or Denso plug and get on with my life.

They look ok, throw them away and get a new set.

Ok. What about how to set the gap on new plugs? The new ones I got had varying gap spaces. The service manual says 0.8mm and some of the new ones were way wider.

What I did was used the plastic butt of a screwdriver to tap on the hook part of the plug to move it closer to the point, and then re-measure. If it was too close, I used a needle-nosed plier to pull the hook out, and try again.

To me, this was too amateurish. Is there a proper way? I searched the web and did not find a good description of how to do this.

Sorry about the lighting... But does it say anything to you re rich or lean mix?

Thank you Andy,

Chris

Doesn't say too rich or lean? I have nothing to compare with really since I haven't seen much or didn't really pay attention to these in the past.

Thank you Joseph,

Chris

YOUgoto the auto parts store and get a gauge. It will have a thing on it that you use to bend the gap. What you are doing is ok.

It's hard to tell get a good view of the plugs because the lighting is not the best. From what I can see the plugs look about normal but a few look slightly overheated One thing I did notice is that you are not tighnening the plugs enough. You can see the spark plug gaskets at the top of the photos and the gaskets are not deformed at all. They should get crushed when the plug is properly tightened. Torque should be 20ft/lb. If no torque wrench, install finger tight then tighten with ratchet 1/4 to 2/3 turns more.

Under tightening of the spark plug can cause plug overheating and possibly pre-ignition. This is because one of the primary purposes of the spark plug is to remove heat from the combustion chamber, it does so by transferring that heat to the engine head. If the plug is not properly tighten it will not have sufficient contact with the head to transfer that heat.

Never seen anything like that before.

I have downloaded the description and picture and will get one soon.

Thank you Ralph!

Chris

Crikey! Super glad you caught that! I always install finger tight, and turn an additional 1/16 turn per the instruction leaflet. But apparently it is not yet enough to crush the plug gaskets.

Thanks for the great catch Mike.

Chris

NGK?Nippondenso are less than $2 each new! Don't waste your time -- internaly they often go bad too and you can't see that. Just buy new ones.

Hi Wolfgang,

Yes, I did buy new ones.

Now, I just wanted to know if these old plugs tells me anything about the air/gas mix. Do I need to adjust the EFI etc.

Well, it turns out that from the pictures, Mike saw something else: that I wasn't tightening the plugs enough, so that it would do its other job of heat-reduction...

Thanks,

Chris