Checking spark plugs for fuel mixture

[ridelikehell]

I remember seeing something about how you can check if you're running too rich or too lean based on the colouration of the spark plugs...

Anyone?

[GeorgiaSnake]

You can do it but it requires pulling plugs on the side of the road unless you have access to a race track. You need to run the car at speed under full load and kill the motor - coast to a stop and pull the plugs. The gas we have now doesn't give you much of a read either.

Randy

[Bruce Edwards]

Basic rule of thumb, black with soft carbon to rich, very light tan to white to lean, a nice medium tan is what you want to look for. You need to look at just the tip, center electrode and ground wire as the unleaded fuel will leave a black trace on the edge of the plugs even if they are running a good mix.
Check this site
http://www.bullittarchive.com/Mainte...g_Spark_Plugs/

[ridelikehell]

Thanks guys!

[ebustin]

In short track racing where time is limited we lool at the threads 3 ring of color is good. Other wise do like Randy said.

[vettestr]

Reading plugs is an art but only possible under fixed conditions and of small value with electronic injection. I see you are running a carb so suggest purchase of a stand alone 02 monitor for about 100 bucks. Then pay close attention to placement of sensor as too cold exhaust gases are very misleading.. You can just intall sensor and then use a digital VOM to read output. A 2 wire or non heated sensor is only about 30 bucks and can use your high impedance volt meter for test readings. A buddy can jot down readings under different drive conditions but then you have a hole to plug in exhaust when senor removed. They are the same thread as a spark plug 14mm if this helps. In the long run take it to a trained ear or pay for a chassis dyno