HC levels on emissions test.... PASSED, good ole Metro Nashville Options

[malcolm2]

'75 1911 L-Jet with about 7000 miles on it, and a fresh oil change this week. Fresh injectors before the first test. Probably running 87 oct E10 gas today. Might have been 93 100% last year.

12 months ago I passed the state county sniff test here are the results from 10/2013:
HC 399 limit 500
CO 0.65 limit 5.0
CO2 11 no limit listed

and from just moments ago 10/2014:
HC 428 limit 500
CO 3.83 limit 5.0
CO2 11.53 no limit listed

2 different inspection stations, not sure if that matters.

The CO seems to have jumped. I did tweek a few teeth on the AFM between the tests. IIRC I have moved it 9 teeth.

Plus the HC is getting close to the limit. I can't remember the RPMs during either test, but they tend to be about 1000, a bit high.

It passed but I want to be pro-active, any thoughts about the CO jump and pulling the HC down for next year?

Clark

[Cap'n Krusty]

'75 1911 L-Jet with about 7000 miles on it, and a fresh oil change this week. Fresh injectors before the first test. Probably running 87 oct E10 gas today. Might have been 93 100% last year.

12 months ago I passed the state sniff test here are the results from 10/2013:
HC 399 limit 500
CO 0.65 limit 5.0
CO2 11 no limit listed

and from just moments ago 10/2014:
HC 428 limit 500
CO 3.83 limit 5.0
CO2 11.53 no limit listed

2 different stations, not sure if that matters.

The CO seems to have jumped. I did tweek a few teeth on the AFM between the tests. IIRC I have moved it 9 teeth.

Plus the HC is getting close to the limit. I can't remember the RPMs during either test, but they tend to be about 1000, a bit high.

It passed but I want to be pro-active, any thoughts about the CO jump and pulling the HC down for next year?

Clark

I've been preparing cars for smog checks here in California since 1973. For a T4 (or T1) engine with L-jet and solid lifters, the two things I have found that do the most for reducing HC levels are running 87 octane fuel and setting the valves to .016" for the test. Along with the most volatile fuel, the late opening-late closing valves provide more time for the mixture to burn, and unburned fuel is what high HCs represent. The high CO reading is likely to be the result of not enough spring tension on the AFM flap. Sounds like you adjusted it to be fatter, so you might want to tighten that up a few clicks.

The Cap'n

[malcolm2]

I've been preparing cars for smog checks here in California since 1973. For a T4 (or T1) engine with L-jet and solid lifters, the two things I have found that do the most for reducing HC levels are running 87 octane fuel and setting the valves to .016" for the test. Along with the most volatile fuel, the late opening-late closing valves provide more time for the mixture to burn, and unburned fuel is what high HCs represent. The high CO reading is likely to be the result of not enough spring tension on the AFM flap. Sounds like you adjusted it to be fatter, so you might want to tighten that up a few clicks.

The Cap'n

Thanks Cap'n,

I did forget to mention that I run (or at least set originally) the valves at 0 lash having chromoly push rods.

So FOR THE INSPECTION I should adust the valves a bit and fill up with the cheap gas?...... I am thinking "only if I fail next year" then I have 10 days to re-test. (IMG:style_emoticons/default/driving-girl.gif)

On the AFM, I followed the itinerant-air-cooled test where you move the wheel with your finger and listen to the engine. At the time of the final test the gear was perfect.