View Full Version : CO2 emissions

Dave Gilbert
16-02-04, 05:05 PM
I have a 350 Chevy (1978 block)with a Carter Competion 750 carb.
Hydrocarbons are OK at about 600 (less than the required 1200 for SVA) but the CO2 is around 7% - way over the 4.5% required at idle although they reduce to about 2.5%,well under requirements, at 2000 rpm. SVA insists that CO2 is less than 4.5% at idle; if CO2 passes at idle but not HC then revs can be increased to 2000 for HC testing but not vice versa so that does not help me.
So my question to you learned folk is how do I get my CO2 down to less than 4.5%?
Any advice would be highly appreciated.
One complicating factor is I have no idea what cams are fitted so setting the tappets is a bit of guesswork. I have solid lifters and gap is currently set at 14 thou.
Many thanks ..

16-02-04, 10:50 PM
Hi Dave, sorry that I can't remember which way around it is, but if you try either increasing or decreasing the fuel mixture, you will be able to get the CO2 to the level you need it. As one goes up the other will go down, so if you can do it with a machine to monitor things ( a local garage or mobile tuner ) you will be able to get it more or less as you need it.


Martin :tu :tu :tu :tu

17-02-04, 09:25 AM
In general if you reduce the co at idle to within the 4.5% limit you will see that the HC rises.
In which case to pass the SVA you can raise the test speed for HC to 2000 as you already know.
I had the same problem with the stroker.


Kev Davies
Dax, 383ci Chevy Stroker, Tremec TKO
South Wales

Dave Gilbert
17-02-04, 03:26 PM
Many thanks,
I will talk sweetly to the local garage again and make some adjustments to the idle mixture whilst hooked up to the analyser so I can see what is going on.
Appreciate the help...