Gas Analyzer....

[Roverchef]

Well I got the 5-gas analyzer work'n @ the shop and after I dial'd in the motor this is what I got. I read the workshop manual and it said to try and get 2-4% on the CO. I am @ 1.14% on the CO and 1.30 on the O2 and 100 particles per. I thought rule of thumb was to get the CO/O2 close to one another as long as they are within spec and the particles 200 or less...? It runs perfect and idles @ 890-910RPMs. Are these #'s good or am too low? Any "Gurus" out there want to chime in?

[krick3tt]

Pretty sure you would pass emissions in Colorado with those numbers, but the guru's should chime in here.

[Roverchef]

I know I would pass emissions but my concern is that I'm running too lean...?

[Jimm391730]

my concern is that I'm running too lean...?

Running lean makes the engine run too hot - possibly burning/melting pistons or other ugly things. But when idling the engine is not running fast nor with a load so it can't really get too hot from being lean; and since this is where most emissions would be tested it is best to adjust the idle circuits for the best test results.

When actually driving the main jets are in use and these set how rich or lean the engine runs (along with the altitude, temperature, and other considerations) and the idle circuits are not really in use. This is one reason why carburators are so complicated, there are different passages for fuel and air (and adjustments) for different modes of operation.

So a lean idle does not mean lean "running", and vice versa.

[Stekay]

the idle circuits are not really in use

I would not agree with that one point, however overall I'd agree that Roverchef is safe and should just read his plugs directly after (no idling) a good highway run to determine his mixture.

[Jimm391730]

Once you start opening the throttle by 30% or more, most all of the fuel comes from the main jets and venturis. Yes, some still comes from the idle circuit but actually less than at idle since the vacuum is reduced (assuming the engine is under load). The idle fuel enters the carbs just under the throttle butterflies where the vacuum is high at idle; as soon as the butterflies open the vacuum is broken and there is not as much suction to pull fuel through the idle circuits.

As the flow of air increases as the throttle is opened, the venturis create their own vacuum to draw fuel through the high speed circuit. Much more fuel flows to match the increased airflow. As the fuel through the idle circuits is diminished, the proportion of idle fuel becomes almost insignificant. Ask anyone who has had a bad idle solenoid (or has had the wire fall off when running, as I have) on the highway the engine runs exactly the same, but come to a stop and the idle is terrible with only one solenoid (no fuel to one cylinder) dead or disconnected.

Theory aside, your suggestion to read the plugs is certainly a good idea to check the "loaded" or "running" mixture.

[Roverchef]

I want to thank Dennis for his guidance. If you have never used a 5-gas analyzer on your Pinzy...just to see if you set it up right (not for smog) and dialed it in correctly, how cool! My #'s were way perfect for passing smog(if I had to) but what it told me was that by stick'n my nose in the tail pipe enough I got it set up and got a buzz @ the same time. Thanks again for the help from a really great and friendly web site!