<VV> Combustion efficiency & exhaust emissions

[FrankCB]

Daniel,
     Years ago when I was driving my 1965 140 Corsa (before Jim "inherited" it) regularly to work, I had to pass NJ yearly emission inspection, done, fortunately, only at idle speed.  At lunchtime I would get out my timing light and retard the timing back to around zero at idle and lean out the primary carbs as much as possible to still retain a smooth idle.  Of course that much reduced advance would require the carb idle speed screws to be advanced to bring up the idle speed to around 800 rpm.  But that, in turn would "bring in" the vacuum advance on the distributor, thereby advancing the base timing.  I had to defeat the vacuum advance by disconnecting the hose on the distributor and plugging it.  This all gave me a very sluggish running car and felt like I had lost about 100 hp.  But I drove it to the nearby inspection station just a few miles away and it passed quite easily.  Then I drove the car back to the company parking lot and restored all the settings back to normal thereby restoring the full power, at least for the next 364.9 days.<GGGG> 
     The point is to lean out the mixture in the carbs (reducing CO) but still keeping smooth idle, raise the idle speed a bit, and retard the basic timing to raise the combustion temperature thereby reducing the HC emissions.
     Good luck!
     Frank "try it, you'll like it" Burkhard 



In a message dated 11/18/08 17:13:43 Eastern Standard Time, dmonasterio at megared.net.mx writes:
  Here, in Guadalajara, Mexico, the maximum exhaust emissions allowed for my vairs are: HC - 300 ppm and CO - 3.00 %, verified once a year for cars and twice a year for pickups (Rampside). Next year will be twice a year for all pre 1993 vehicles without allowing driving them on peak hours. 
  Is there a way to modify Corvair engines to make them meet say, 1994 or newer, emissions tests ?... I've been driving Corvairs most of the time since 1968 and wouldn't like to change my driving habits. Don't like driving other cars but Vairs only !! 

Thanks in advance for any tip 

Daniel Monasterio