<VV> Catalytic Converter for Corvair

[bernievogler at comcast.net]

Craig is close on the rotten egg smell.  The smell is from Sulfur Dioxide (SO2) which could be a product of the thermal decay of sulfuric acid (H2SO4).  The sulfuric acid is most likely to exist in a cooler motor, but once warmed up should remain as SO2 and H2O through the entire exhaust system.

Bernie Vogler

> Craig opines:
> The typical catalytic converter converts CO and HC to CO2 and H20, assuming
> the components are fed from an engine that's running neither rich nor lean
> but in exact 14.8:1 ratio of fuel to air.  Corvairs are not calibrated to
> run at this stoichiometric ratio.  Usually, they are relatively rich.  This
> puts the cat into the business of burning the excess HC, which is what
> creates the "rotten egg" smell (H2SO4?).  After a steady diet of excessive
> HC, the catalyst's substrate will melt, fuse, and clog the exhaust.  There's
> also a fire hazard, especially when they're fed excess HC, which is why cats
> have a heat shield on the upper side. Excessive backpressure can burn
> exhaust valves too. 
> 
> '68 and '69 smog engines might have the best chance of all years for this to
> work 'cause the carburetors have more accurate mixture control.  Since
> you're a pioneer, keep us posted!  The only other Corvair I've heard of with
> a cat has a 4.3V6!
> Craig Nicol
> 
>