Guess I need new spark plugs
Road Warrior
Joined: Apr 2010
Posts: 1,739
Likes: 10
From: Suffolk, England
Quite a few folks still try to read plugs by various old and unreliable methods. The only one that works well with modern clean/unleaded fuels is to look at the base ring; all the other bits (porcelain, strap, etc) don't tell you much about the fuelling.
See the Jetting section here: http://www.dragstuff.com/techarticle...ead-plugs.html
Hard to tell from a photo but I'd say yours look pretty good.
Oh, and the condition...Nothing wrong with that. Bit of water got on there is all. My car's plug change interval is 20,000 to 30,000 miles and they looked fairly tired after that but still worked perfectly.
See the Jetting section here: http://www.dragstuff.com/techarticle...ead-plugs.html
Hard to tell from a photo but I'd say yours look pretty good.
Oh, and the condition...Nothing wrong with that. Bit of water got on there is all. My car's plug change interval is 20,000 to 30,000 miles and they looked fairly tired after that but still worked perfectly.
Last edited by Foxster; Jul 13, 2013 at 04:00 AM.
Grand HDF Member
Joined: Sep 2017
Posts: 4,359
Likes: 1,219
From: Dubuque, IA
Reading the AFR is done way down where the porcelain meets the shell. a short distance up from where these meet should be a ring on the insulator and color a short distance up the shell. The base ring is idle afr and color should go down the first 3 threads.
The ground strap is heat range and timing. You should see 2 distinct colors. One from the tip to half way to the curve where you should see a change that goes around the curve to not quite to the threads. The first being initial timing and the second max timing.
The insulator you see is suppose to be white. If it's glazed over white it's too hot. So is a dark reddish burnt color. Grayish/blackish specs are signs of detonation.
The days of a bright copper color went bye bye with leaded gas.
You really need a lighted magnifying lens to read AFR on a plug. Except for idle AFR.
Here"s a cheap lighted magnifying lens used to read plugs. The LED light is burned out.
The ground strap is heat range and timing. You should see 2 distinct colors. One from the tip to half way to the curve where you should see a change that goes around the curve to not quite to the threads. The first being initial timing and the second max timing.
The insulator you see is suppose to be white. If it's glazed over white it's too hot. So is a dark reddish burnt color. Grayish/blackish specs are signs of detonation.
The days of a bright copper color went bye bye with leaded gas.
You really need a lighted magnifying lens to read AFR on a plug. Except for idle AFR.
Here"s a cheap lighted magnifying lens used to read plugs. The LED light is burned out.
Last edited by 60Gunner; Jun 3, 2023 at 07:26 AM.
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