[Kube]

Originally Posted by Karl Wescott

The catalytic converter works by enabling hydrocarbons to burn at a dramatically lower mixture (air + fuel) than what they would normally burn at. They are often some alloy of platinum in a ceramic (high temperature tolerant) matrix. "Flooding" does not seem to damage converters, however it will take time to burn out excess fuel, which causes heat, which must be dissipated safely. The converter also has to reach a certain temperature (400F?) to begin operating.



What will KILL a converter is heavy metals... especially lead.


The "rotten egg" smell. Yes to incomplete combustion, but a required component to get the smell is sulfur. Various sulfur oxides STINK! And contribute to ground level ozone. This is one of the reasons that regulators (EPA) are demanding "low sulfur" fuels. Ironically this is why we import oil from the middle east (naturally low sulfur) and export oil from Alaska to Asia (naturally high sulfur, and lower regulatory limits).



IIRC from the discussions when EPA rules started to come out that stock flatheads could be tuned to run quite clean. Compared to 60's OHV the flatheads relatively long stroke to small bore allows extra burn time for a more complete combustion of hydrocarbons, and relatively low compression reduces the formation of nitrous oxides (nitrogen is ~80% of air).

Thank you Karl!