Reading a spark plug

[wally426ci]

So, i just changed my AutoLite Platinum plugs to Champion RN12YC (recommended from a buddy)

I noticed that the electrode was worn in the middle (almost in a cone shape)

the insulator was a frosty white with a little tanning, and the color change on the ground strap was a little closer to the threads than in the middle.

this article notes that that can be caused by too much timing http://www.4secondsflat.com/Spark_plug_reading.html
but does that mean i have too much advance? or too much initial....?

 

[GoodysGotaCuda]

looks a little leak and the timing is too far advanced. best reading for mixture would be a brand new plug at full throttle with minimum idling. i believe that is too much advanced, ill have to look at my stuff and see for sure.

[moper]

First, I'd say yo are very close, the timing might be a little off, but I look for flecks or black spheres on the ceramic with a magnifying glass if I'm worried about it. Second, that's a platinum plug.. They come that way (center electrode I mean...) It's not worn. They put a sharp corner on them so the spark jumps easier.

[wally426ci]

Very interesting......... 

Thanks!

[DanGoodman]

You really should use NGK plugs.........they work best on High performance engines - 02

 

[nivvy]

If the discoloration is to close to the top you are running 2 cold of a plug... too far down the strap closer to bottom and you are too hot... you wanna find a plug right around the middleish about 4-5 threads down.... depending if its an extended reach plug or not...

[MEK-Dangerfield]

Wally,

 I would throw that sucker back in and not worry so much. You have to be close, if not just about "on" with timing and carb jets size.



   Mike

[wally426ci]

Really? i was convinced that i need to downsize my metering rods and jets, its a little rich in the highway cruise. I have always thought ive had a little bit of a miss.....

Oh well, i already changed to the champion plugs, so if they suck i'll run NGK 

[GoodysGotaCuda]

Wally you'd need to upsize metering rods if you are running rich. Thicker the rod, less fuel = leaner. However that plug doesn't look rich to me..

[Chryco Psycho]

the pic at the top of this thread looks way lean to me , you will pick up milage & power if the plugs are in the tan brown range

[wally426ci]

So, i need to Richen this puppy up..... Im going to work on fine tuning it in the next couple weeks. I havent worked on it much, not to mention having not driven it further than a few miles this year...... been busy...