Contour Enthusiasts Group Archives Forums Modifications General Mods "reading" Spark plugs?

I know the general ideas about picking up on whats going on iside your engine by looking at the plugs, but I can never seem to remember which is which. I changed my plugs last week and the plug electrodes(?) were mostly light ash grey with very small patches of light brown, but what really worried me was the thick, crusty, sooty residue around the collar(?) at the bottom of the plug. Any body give me an idea of what's going on?

Sounds fairly normal for a hot running 4-cylinder.

White, wet, and/or erroded plugs are the big things to watch for.

People that use octane booster may get a reddish or light brown tint to their plugs. Still normal.

I realize that this is from ClubSi.com, however, they do a great job describing the different spark plug scenarios. Just follow the link .

Great link, but the info is a little old. When is the last time you filled your tank with leaded fuel? The information is timeless otherwise. When this question was first posted I started looking for a link for this type of info but gave up. This info used to be part of any spark plug catalog.

All of that information is relevant. They were just showing you what lead fouling looks like. Granted most people will never see a lead fouled spark plug but you can't blame them for being thorough.

Do they look anything like my plugs.

If so, they are normal (according to those that commented on them). You can read my thread here.

They look pretty normal to me. The view of the firing area is not that good so it is hard to tell. The plugs you are showing are the fine wire platinem tip that has been original equipment for the Duratec since about 1996. It is a single platinum tip, the center wire. The platinum tip is very skinny and long (the "fine wire"). Some have mistaken this for a badly eroded tip. The color of the tip is very slightly dark, but well within the range of normal. I cannot tell much more without a better picture of just the firing area.

saw this info posted on a turbo omni site, most of it should be relevant here??

How do you read your spark plugs? Here are some guidelines. Install a new set and then go for one WOT pass down a back road. Now pull each one out (be careful not to burn yourself!) and look very closely. You want to see sharp corners on the electrodes and no "salt & pepper" on the center porcelain insulator (salt = tiny melted aluminum globs, pepper = carbon deposits that have "splashed" onto it). If the electrodes have sharp corners before a run and rounded corners afterwards, you're probably lean; add fuel. Salt and/or pepper is probably from detonation; retard timing, or lower compression. Cracked porcelain is definitely from detonation; retard timing, or lower compression significantly (such as with a headsaver gasket by Fel Pro). Real dark porcelain = too rich; take some fuel away. Grey porcelain = good; yellow porcelain = gasoline additives; rust-colored porcelain = 104 octane booster.

the info comes from a fellow named dempsey bowling, i highly recommend his page if youre ever searching for 80's mopar info. just do a google search for dempsey bowling, there arent too many people with his name.

What you are refering to is a tool for a mechanic to tell if he has the correct heat range on a highly modified engine and also as a method of telling the health of an engine. This is referred to a "cutting clean". It entails shutting the ignition off during moderate acceleration, when the fuel system should be "clean" (not overly rich or lean). For the most part, there are better ways to tell the same thing today. This is a throwback to the 50's.