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

[era vulgaris]

That's a bummer you have to get your car inspected. Right next door to you here, anything over 35 years old, pay insurance and registration, they hand you a plate, and off you go.

[GregAmy]

Interesting you have to go through emissions...even the Socialist State of Connecticut exempts everything older than 20 years...

I had a Nissan with an imported Japanese market high-compression, variable-valve-timing engine in it, and I was able to get the thing through emissions every two years. We do a rolling-road test here, not an idle test, somewhere around 3000 RPM. To pass the test, I'd back the base ignition timing 7 degrees to lower the NOX, and I'd add two gallons of denatured alcohol into the 10 gallon tank (with top off) to get the HC down. Passed with flying colors.

On the other hand, these tests are so inconsistent year-to-year and station-to-station that I'd not even worry about it if you're below the limits. I don't see anything that makes me worry about a latent problem.

GA

[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]

That's a bummer you have to get your car inspected. Right next door to you here, anything over 35 years old, pay insurance and registration, they hand you a plate, and off you go.

It is my own fault. 1975 is the last year to get inspections. If I had bought a 1974 I would not have to deal with it.

I should make a correction. It is not the STATE it is Davidson County. Years ago they decided to do this test, and included the 7 contiguous counties of which I live in one.

But you are correct, they should just make it 20 years of testing and then stop. I suppose some brilliant politician figured if they did that everyone would be driving 21 year old cars so the new car dealers would suffer.

The increased use of older cars might happen for a year or two, then it would be back to normal..... dumb asses! (IMG:style_emoticons/default/stirthepot.gif)

[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.

[Cap'n Krusty]

I would think that adding some clearance on an engine normally running zero clearance would work just fine. IME, the .006" clearance remains pretty much the same as the engine comes to operating temps, so adding .010-.012" should make a similar change in HC emissions. Not gonna hurt anything for the short time you're running it that way. I usually run the tank low and add only 4-5 gallons of regular, not a full tank. You really need to set the AFM with a CO machine ...

The Cap'n

[mepstein]

Move to PA. One time fee of $75 for life antique registration and no safety or emmission test ever. (IMG:style_emoticons/default/biggrin.gif)

[malcolm2]

Move to PA. One time fee of $75 for life antique registration and no safety or emmission test ever. (IMG:style_emoticons/default/biggrin.gif)

TN antique tags are a lifetime thing too. Even cooler is they let you use a tag from the era of the car. But you are only supposed to drive on weekends, to shows and parades. If you get caught and the cop is a wiener, you owe the fees from the day you got the tag. $50 a year for however many years your car has been an antique.

Got pulled over once in my 85 VW with a tag that someone used in 1985. the dude was cool and let me know the deal.

Clark

[mepstein]

Move to PA. One time fee of $75 for life antique registration and no safety or emmission test ever. (IMG:style_emoticons/default/biggrin.gif)

TN antique tags are a lifetime thing too. Even cooler is they let you use a tag from the era of the car. But you are only supposed to drive on weekends, to shows and parades. If you get caught and the cop is a wiener, you owe the fees from the day you got the tag. $50 a year for however many years your car has been an antique.

Got pulled over once in my 85 VW with a tag that someone used in 1985. the dude was cool and let me know the deal.

Clark

PA allows for occasional driving including driving to work. So does my insurance at $130/year.