That article of Monty's needs better pictures.
I've started taking pictures of various plugs, but need to get a lot more showing things clearly. Here's a picture of a plug out of my car, last pass of the year. This clearly shows the fuel line and that the car was running rich. Also you can see some specks on the porcelin, that might have been caused by the use of Torco 118 fuel. Some people have noted seeing that condition when using that fuel, but don't know why that fuel does it.
I'd like to get a collection of "perfect" looking plugs, and plugs showing various stages of tune.. Too much timing, too little timing, too much fuel, too lean, etc.
I think a very complete picture gallery with comments on what to do would help a lot of nitrous guys out.
Mike Canter wrote a pretty good article about plug reading that we have in our technical section of the site
http://www.dragstuff.com/techarticles/reading-spark-plugs.html however it needs pictures.
Here's another one that is interesting.. This plug was taken out of Bob Stahl's 69 Camaro last year after a pass. It's an Autolite. What makes it interesting is that this plug quit firing on the previous pass. All the other plugs in the engine were light grey from soot. But this one is clean.. The fire went out in this cyl and the fuel was washing the soot off. He switched to a new plug and the miss went away. On a side note, I check this plug with an ohm meter, and is was very close to the same resistance as a NGK, nothing obviously wrong with it.
