JL66REDCPE
Well-known member
Those on this forum who know me also know that I do not get into the car at all except on very rare occasion. Anyway, I was coming home from a show on Sunday and brought the car up to 3500 rpm in first then second -- everything ok so far -- went into third and engine started missing. Hmmm -- never had this happen before. My first thought was a fouled plug, then maybe wires or dist cap -- same ole same ole. On Monday I pulled the plugs. All 8 were bone dry with no oil fouling or carbon however each plug was kind of encrusted with this reddish/orange/tannish stuff. It was on the side electrode, insulator and the bottom rim of the plug. Well, I got out my spark plug diagnosis color chart and learned that it was residue from MMT which is used as an anti-knock additive instead of lead. I cleaned the plugs, put them back, took the car out for a test and everything was fine. Since I use a 50/50 mix of leaded 112 race gas and 93 pump premium, the deposits could have been coming from one, the other, or both. I called the racing gas company and one of their engineers assured me they do not use MMT and in fact use lead in the racing gas I use. That left the 93 pump gas as the probable culprit. The engineer also told me if the pump gas was oxygenated that could also cause the deposits. I have been using Gulf 93 in the car because of convenience. The plugs were last cleaned and re-gapped last year at the start of spring.
Has anyone else run into these kind of deposits on their plugs ??
Has anyone else run into these kind of deposits on their plugs ??