Emissions testing

Eric F · Post by **Eric F** » Tue Aug 01, 2006 8:24 pm

Good evening roadster maniacs!

I have a small question about adjusting a roadster for emissions testing..

Illinois regulations... HC > 900, CO > 9.0, CO2 is informational.
Two years ago, with ailing engine and hurting carbs... HC= 891, CO=6.3, CO2=9.7
Today HC=818, CO=9.1 (fails), CO2=9.0

I have a rebuilt engine now running 20W50 Valvoline synthetic oil, Z-therapy rebuilt carbs, Gary Boone EI dizzy at 19 degrees advance. I have to run 93 or better octane fuel to keep the car happy as well. So, any thoughts to get this car to pass? Won't take much to pass, but not sure what to change to get the CO down. Thoughts??

Eric

Post by **spl310** » Tue Aug 01, 2006 8:30 pm

Hi Eric! Haven't seen you post in a while!

As I recall, what some folks would do is to lean it out to the point that it barely runs and then take it in. Some have gone so far as to putting a smog dizzy and jets in before testing, then returning it back to what it really needs after returning home.

Of course, you could drop the engine into a 66 and bypass all of that fun...

Post by **George H** » Tue Aug 01, 2006 8:34 pm

High HC and CO indicates rich mixture. Try leaning it out slightly, but not too much to the point of lean misfire. This will cause the HC to rise again because of incomplete combustion. HC can also be high if your car burns oil.

bandit610 · Post by **bandit610** » Wed Aug 02, 2006 1:16 pm

It really depends on what rpm range the test is at. If you're running it at 2500, adjusting the idle mixture isn't likely to help. Also, high float level can richen the mixture. What year is your car? did it originally have an AIR pump? I'd also talk to the folks you got your carbs from., they may have set them up to run fatter than stock, since most of the states don't need to smog these anymore.

Marky510 · Post by **Marky510** » Fri Aug 04, 2006 12:37 am

if those are idle readings, you must have fuel just dripping out your tailpipe. lean those carbs out to about 4% CO at idle. your CO2 should rise and HC should drop as well. and the car might run better too (CO2 indicates combustion efficiency, so the higher the better). Also kick the idle speed up around 1000 rpms, that should help clean up the numbers. some smog machines max out at 9.9% on CO, so your readings are almost maxed.