reading plugs

[martyb]

can someone post a pic of plugs that have been subjected to detonation? Trying to learn more about this plug reading thing. I pulled a few plugs yesterday and they all look nice and clean. I am thinking about adding in a bit more timing, but before I do, I want to know exactly what I should be looking for if I encounter any detonation.

martyb

 

[GTSnake]

This is what happens with Detonation! I think it's pretty easy to read.

 

[Cris]

Yikes, hope that is not yours!

 

[GTSnake]

Yup, but I didn't blow anything.

 

[martyb]

Thanks GTSnake. I was focusing on the cermamic part of the plug, but your pic clearly shows deposits on the electrode. Where should I be looking??

 

[GTSnake]

Detonation is mostly detected by your ears or a sensor. I'm not sure the spark plug is a good indicator. But my take is the spark plug only shows how rich or lean your mixture is not if you have detonation.

I'm sure someone else more knowledgeable than me could correct me if I'm wrong.

 

[Jack B]

The spark plugs show everything, the problem is you have to shut down totally after a run. You then view them with a high power magnifier. Your plug looks like it was running in the lean region for some time. True detonation could have broken the electrode off, or cracked the insulator. Severe detonation tries to rotate the engine to close too tdc, or ties to move the unmovable.