Plug Chop guide with Photos

[skuttadawg]

www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

[mopojo]

Good post. Wonder if some-one soon asks how to perform a plug chop? ;D

Breezy

[onilegion]

Hi skuttadawg,

Unfortunately the NGK pamphlet that those photos are from is from 1977, and who knows how much earlier the photos were actually from.

Some of the photos may still be useful, but fuel and oil compositions, as well as engine clearances, have changed so much from that time that the photos are no longer good guides for fine tuning mixtures via the plug-chop method. In general modern plugs on modern engines using modern fuels/oils will have a "cleaner" look across the entire range of photos.

Here is a good guide to fine tuning mixtures via the "plug-chop" method.

www.angelfire.com/fl4/pontiacdude428/Readplugs.html

This is assuming that the person doing the tuning has enough knowledge to get the engine within a safe (usually slightly rich) and reliable running condition before attempting the fine tuning. If someone cannot get their AFR within ~1.5 - 2.0 "points" of stoichiometric first, then fine tuning via this method is not going to reveal much information. We have found this guide really great for checking on the proper heat range of the plug, especially after making significant changes in the compression ratio,

There are also some guides to even more accurate plug reading by observing the "fuel ring" near the base of the ceramic, on freshly pulled plugs from chopped engines. We were amazed at how much info a talented reader can get by using this method, but it is tough to learn. We have our spark plug scope and are trying to learn this technique, but for right now we definitely defer to the experts on this one , and continue to use our portable AFR meter to do the ultimate fine tuning.

Tuning is not a crime (well sorta not too illegal , right?),
onilegion <><

[skuttadawg]

Tanks plus diff gasoline brands have additives and results will vary .

I have done IT and handy man work for years . I laugh when a computer gets mad when they can not find the any key . Had one ask why the drink holder closed when he rebooted ( the cd drive ) . I found a live green grass snake in a tower once . I called to see if it was a pet and since it was not I let it go into the woods behind the shop