OT: My tow rig failed emissions! Options

[Eddie914]

My tow rig failed emissions today in Seattle!

1983 Chevy 454 with a Quadra jet pushing a 27 ft motorhome chassis.

It failed the Carbon Monoxide at idle test.

HYDROCARBON (ppm)

Cruise Limit: 220
Cruise Emissions: 33
Idle Limit: 220
Idle Emissions: 128


CARBON MONOXIDE (%)

Cruise Limit: 1.2%
Cruise Emissions: 0.75%
Idle Limit: 1.2%
Idle Emissions: 4.78%

Unfortunately the idle mixture screws are sealed on this carburetor (for the time being). The air pump has been removed.

What is interesting is that since I replaced the heads to rectify the badly worn valve seats the HC has gone substantially down and the CO has gone substantially down.

Are the HC and CO inversely proportional?

Should I lean it out? Should I richen it up? … or should I just shoot it?


Thanks

Eddie

[Cap'n Krusty]

QUOTE (Brew @ Aug 9 2005, 02:43 PM)

Carbon monoxide is the incomplete burn of carbon molecules found in fuel. Lean it out, or maybe advance the timing just a hair. Also, make sure your spark plugs/wires/distributor cap are all in excellent working order, and it doesnt hurt to run the vehicle HARD right before the testing is done. I usually run a higher grade of fuel for the test if there's any chance of it failing. Good luck!

Running a HIGHER grade fuel will ensure a marginal car will fail. Higher octane fuel isn't as volatile as low octane varieties, and won't burn completely in a car not designed for its use. ANOTHER internet promulgated MYTH. Not the right thing to do. Plugs, wires, cap, and rotor will all contribute to high HCs, NOT CO. HC is unburned fuel. CO is just plain too much fuel per parts of air. Bad air filter, improperly adjusted carburetor, stuck float needle, sunken float. Very high or very low CO will result in high HCs. A good working cat will eat up a LOT od HCs, and some CO. The air pump will clean up a lot of CO, as well as some HCs. Advanced timing INCREASES HCs, and the NOX numbers suffer. Removing the air pump is a questionable practice on a vehicle that has to pass en emissions test. In states that use the California standards, missing emissions control equipment is an automatic fail, no matter how clean the tailpipe is. The Cap'n