Nitrous Spark Plug Pictures
by John Heard and Friends...

Too lean and too hot, time to back some timing out of it and add some fuel. This plug has a blue tint to it due to the camara flash used, it didn't look that blue in regular light.

The above plug from a nice clean mid 9 second pass, this one was a little bit lean, added 1 psi fuel to it and picked up 3 mph. Note: Might need to take a bit of timing out of this tune up or use a colder plug, some deterioration on the center electrode however ground strap looked about right.

"Pepper" AKA Detonation. This was in a car that was running so rich that it blew black smoke out of it, but had too much timing. Note the center electrode is getting ate up a little and the ground strap has the look of metal that was heated up with a torch till it was bright red. The specks on the porcelain are supposed to be due to oil getting into the combustion chamber during detonation. This plug has been washed with brake cleaner, prior to that it had black soot everywhere.

Same car, next pass with 2 lbs LESS fuel, and two degrees less timing. The plug is running cooler now from less timing and is now coloring the porcelain. Now it's time to start backing down the fuel a bit more. This plug has been washed with brake cleaner, prior to that it had black soot everywhere.

Same car, next pass with 1/2 lbs LESS fuel, and same timing. Still see some peppering of the plug, probably getting some detonation. Still rich. Note: The rings were going away in this motor on this pass. We also burnt the clutches out of the TH400.

Here's an interesting one.. The above plug was in a cylinder that went "out", notice the gray down inside. The plug was working, then quit - fuel washed the soot off the rest of the plug. This is an Autolite racing plug, several plugs in this motor did this, the rest all looked gray on the base ring - perhaps a bit on the rich side but motor was running very good.

Ryan's Plugs AKA 66 283. Almost perfect fuel and timing, after this pull added 1-2 degrees more timing to take the heat in the ground strap just a bit more towards the corner bend and picked up 40rwhp.

If you have some pictures of nitrous plugs that you would like to share, please email them to admin@dragstuff.com along with some notes about what we're looking at (tune up, plug numbers, things you noticed etc.) and I'll add them to this page. Also note we have a discussion started about reading plugs in the DragStuff Forum that you might want to participate in.

Additional Spark Plug Related Resources

• Pro Systems Spark Plug Reading Tool Kit
• Spark Plug Reading 101 (Gas)
• Blown Alcohol Spark Plug Reading 101
• Plug reading Discussion going on in our message board
  
• Another excellent "How to read Spark Plugs" article
• How you can read spark plugs and select them - by Gordon Jennings (Note: Geared towards Motorcycles but very good info here. Make sure and read the part about how detonation makes the plug look cleaner.)
• Racing Spark Plug Cross Reference for Autolite, NGK and Champion