What would cause this?????



The burnt ring around the ceramic....Too hot of a spark????

my Formy is running like dog doo and I think this plug is the problem. I have the MSD ignition box, external coil and dist. on her. The car has a slight miss at varying RPM's and is now DETONATING!!!! Going tomorrow to get new plugs and hope this will cure my ills...

Appreciate any and all replies


Later

 

That appears to be a combination of atmospheric and underhood contaminants that deposit on the plug outside of the sealing boot, more commonly called "dirt". Some of it also appears to be iron oxide (rust) that is migrating up from the plug shell. That's a primary reason I prefer Champion plus over the plain Delcos. The Champion plugs are plated to prevent that. Delco platinums are made of a 400 SS so the rust is almost impossible.

I doubt that the ignition system is causing that.

What do the business ends of the plugs look like? That will be a much better indicator of the correct heat range of the insulator. The picture only shows what frequently happens with aging plugs that are exposed to a little oil leakage, water splash from the roadway, and normal dust and dirt. Spark plug boots that allow a little electrical leakage can help attract some of that contamination by ionization, but the rest of the external insulator looks clean enough so that spark energy loss shouldn't be a problem.

Still, if you're experiencing some preignition, a plug with a heat range lower might be a good start to the cure.

 

poor seal around the plug boots

 

Business end looks just right....Not White (lean) and not wet (rich).....I guess since I have not ran my Formy on a regular basis could cause the "burnt" looking ring. I will let you guys know how she runs tomorrow when I get some new plugs (Autolite 104's gapped at .045) for the GM HO crate motor.

Thanks again guys

BTW....We had some Ethanol fuel that came down and I think I might have gotten some. My fuel gauge is not working right (tell tale sign). I have heard that this stuff can really F'UP your injectors. Bought some Lucas injector cleaner and I am going to give it a whirl. Keep you updated

Later

 

I've been using ethanol blended fuel since about 1978. I've never had an injector problem due to the fuel. I have had problems due to storage (evaporative deposits, I think), but I've been addressing that every fall by adding a pint of 2-stroke oil to the last tankful of fuel before storage. I think the pump likes it, too. About all I've done to compensate otherwise was to decrease the injector constant slightly to increase liquid fuel flows about 2%.

All my fuel guages work find as well. Methanol is a very harsh alcohol for fuel systems, but ethanol is relatively benign.

 

Why are your threads on the plug wet?

 

That is the shine only....they are not wet.

 

plug must have been bad....She is running like a champ now!!!

Later